Automatic Speed Control Apparatus for Treadmill and Control Method Thereof

Abstract

The present invention provides an automatic speed control apparatus for a treadmill and the control method including a deck, a track belt of endlessly rotating on the upper and the bottom face of the deck, and a driving unit for driving unit for driving the track belt comprising: at least one front load sensor located in the front part of the track belt for measuring load from a user on the track belt; at least one rear load sensor located in the rear part of the track belt for measuring load from the user on the track belt, wherein the proceeding speed of the track belt is controlled based on the user's location or movement on the track belt by comparing the measured values from the front load sensor and the rear load sensor and catching the user's location based on the comparison therebetween, whereby the proceeding speed can be automatically controlled corresponding with the user's running speed without the user's direct operation.

Description

TECHNICAL FIELD

The present invention relates to an automatic speed control apparatus for a treadmill and a control method thereof, more particularly, to an automatic speed control apparatus and control method thereof for automatically controlling the proceeding speed of the track belt precisely corresponding with a user's intention without the user's direct operation for changing the speed of the track belt while running or walking on the treadmill.

BACKGROUND ART

A treadmill known as a running machine is widely used indoors such as at home or in a sports center as it allows users to have an effect of exercising while working or running on its endlessly rotating belt in narrow space. Recently, a demand for treadmills is drastically increasing due to the advantages of its safety and convenience because users can exercise indoors using a treadmill even in the cold winter.

In general, a user on a treadmill runs or walks with directly changing the speed of running or walking by finger operation so as to enjoy dynamic exercise. In this regard, the user should directly operate the control panel of the treadmill in order to control the proceeding speed of the track belt while running or walking on the belt. However, the finger operation of the track belt speed while exercising on a treadmill can be bothersome and even dangerous for the user on the moving treadmill as it causes to break a balance of user.

Also, as a stereotyped program stored in a treadmill memory is not manufactured without considering a user's body condition, the user should follow the memorized stereotyped program regardless of user's condition. Therefore, although the memorized program has a merit that the user does not need to directly operate the track belt speed during the exercise, the memorized program makes the user to exercise too much or insufficiently

In order to overcome these problems, automatic speed control apparatus of running machine designed by Youngjin Chae, Korean patent No. 2003-0069941 provides sensors 13, 14 comprised of a light emission part and a light receipt part on the front of control panel of the running machine which can sense where user is located. The apparatus accelerates when user is on the front of a track belt and on the contrary decelerates when user is on the rear part of the track belt so that it can automatically control the speed of track belt in accordance with the user's intention. However, as the sensor used in the automatic speed control apparatus of running machine designed by Youngjin Chae costs too much, the machine has a practical problem of losing price competitiveness in manufacturing a running machine with the sensor.

On the other hand, as an automatic speed control apparatus of a treadmill using the sensor had not avoided high manufacturing cost, there has been an attempt to use an ultrasonic sensor for sensing the location of user. That is, an ultrasonic sensor located in a front part accelerates a track belt rotation when the user gets closer to the ultrasonic sensor and on the contrary it decelerates the track belt rotation when the user become more distant. However, the calculation of the distance of user from the sensor using an ultrasonic sensor is not precise so that it causes malfunction which a treadmill accelerates a belt when the user does not get closer to the ultrasonic sensor or decelerates even when the user is not distant from the ultrasonic sensor.

Moreover, a treadmill using a sensor for automatic speed control can cause serious malfunction as sensing simple gesture of running or walking, or a movement for operating a controller located in a front part as an attempt to accelerate a belt. The speed of track belt can accelerate when user does not want to run or walk faster.

DISCLOSURE OF INVENTION

Technical Problem

These disadvantages of the prior art are overcome by the present invention. It is an object of the present invention to provide an automatic speed control apparatus for a treadmill and control method thereof automatically controlling the speed of track belt rotation to user's intention minutely without operating the treadmill specifically for changing the speed of rotation while running or walking on the track belt.

Another object of the present invention is to enable manufacturer to produce an automatic speed control apparatus for a treadmill automatically controlling the track belt with relatively low price.

Still another object of the present invention is to provide an automatic speed control apparatus using a load sensor which senses that user's speed gets faster than the speed of track belt rotation when user is sensed on the front part of the track belt, and therefore the treadmill accelerates the belt. On the contrary, the load sensor senses that user's speed gets slower than the speed of track belt when user is sensed on the rear part of the track belt, then the treadmill decelerates the belt.

Yet another object of the present invention is to provide stable speed change control device avoiding a drastic change of speed.

Still another object of the present invention is to provide comfortable exercise environment minimizing inertial force effect by the automatic speed control of a track belt.

Another object of the present invention is to provide stable speed control environment not to misperceive a movement of a user on a track belt for operating button on a control panel or grasping a hand purse as a sign to accelerate or decelerate the track belt.

Another object of the present invention is to provide a treadmill which prevents possible accidents while exercising on a treadmill in advance. Another object of the present invention is to provide a treadmill of reasonable price that can measure user's weigh on the treadmill.

Technical Solution

In order to attain the above mentioned object, the present invention provides a speed control apparatus for a treadmill including an endlessly rotating track belt, a driving unit for driving the track belt comprising: at least one front load sensor located at the front part of the track belt for measuring a load from a user on the track belt; at least one rear load sensor located at the rear part of the track belt for measuring a load from the user on the track belt; and a control unit for controlling the driving unit to accelerate or decelerate the speed (i.e., line velocity) of the track belt based on the measured values of the front load sensor and the rear load sensor.

That is, by sensing a running or walking user's location on the track belt from the measured loads at the front and the rear part of the track belt, the speed of the track belt can be automatically controlled in accordance with the user's running or walking speed without specifically operating the treadmill for changing the speed of track belt during the user's running or walking on the track belt.

Herein, the control unit controls the speed of the track belt to accelerate when the user locates in the front part of the track belt, and to decelerate when the user locates in the rear part of the track belt by sensing the location and further the movement of the user from the difference(s) of the measured values of the front load sensor and the rear load sensor.

The front load sensor is formed as at least one front load cell and the rear load sensor is formed as at least one rear load cell. Generally, a load cell includes a or plural number of strain gages which is shrunken or elongated by the external load. That is, as the resistance of the strain gages is changed when an external load is applied, the voltage of the strain gage is also changed. From this voltage difference, the deformation of the strain gage is calculated, accordingly, considering the material which the strain gage attaches, the load applied to the strain gage can be measured. Therefore, in accordance with the degree of the user's biased location on the track belt, the front load sensor and the rear load sensor formed as load cell output different voltages, and thus, the load can be measured by processing the voltage signals such as converting the analog voltage signal into digital voltage signal.

For example, when the user is biasedly located at the front part of the track belt, the measured value of F1 at the front load sensor is getting bigger comparing with the case when the user is located at the center part or at the rear part of the track belt. That is, from the changing propensity of the measured value F1, the control unit can sense the user's real time location on the track belt. Accordingly, in case that the absolute value of the measured value F1 at the front load sensor is getting bigger, as the user is sensed to be located at the front part of the track belt, the control unit orders the driving unit to accelerate the track belt. Similarly, when the user is biasedly located at the rear part of the track belt, the measured value of F2 at the rear load sensor is getting bigger comparing with the case when the user is located at the center part or at the front part of the track belt. Accordingly, in case that the absolute value of the measured value F2 at the rear load sensor is getting bigger, as the user is sensed to be located at the rear part of the track belt, the control unit orders the driving unit to decelerate the track belt.

To the contrary, the front load sensor and the rear load sensor can be formed as at least one strain gage. More specifically, the front load sensor is formed as a pair of front strain gages installed at the front part of the track belt, and the rear load sensor is also formed as a pair of rear strain gages installed at the rear part of the track belt, in which the front strain gages and the rear strain gages constitute a full wheatston bridge circuit. Instead, the front load sensor can be formed as a front strain gage installed at the front part of the track belt, and the rear load sensor can also be formed as a rear strain gage installed at the rear part of the track belt, in which the front strain gage and the rear strain gage constitute a wheatston bridge circuit with other 2 dummy resistances.

In case that the load sensor is formed as a pair of strain gages, it is desirable to install a pair of the front strain gages at both sides of the front part of the track belt and to install a pair of the rear strain gages at both sides of the rear part of the track belt, whereby the bias to the left side or to the right side can be automatically compensated. Also, as the resistance changes of 4 strain gages can be represented by a bridge voltage, it is possible to precisely sense the user's real time location with only one relatively expensive amplifier, thereby reducing the cost of the automatic speed control apparatus for a treadmill.

Herein, the front strain gages in the wheatston bridge circuit face each other, and the rear strain gages therein also face each other. In this case, the bridge voltage ΔV can be expressed by following equation 1.

$\begin{array}{cc}\Delta V=V\frac{R1-R2}{R1+R2}& \mathrm{Equation}1\end{array}$

Therefore, the resistance R1 of the front strain gage is getting bigger when the user is biasedly located at the front part of the track belt, while the resistance R2 of the rear strain gage is getting bigger when the user is biasedly located at the rear part of the track belt. Therefore, the sign and the absolute value of the bridge voltage ΔV senses or catches the user's location (i.e., how much the user is biasedly located on the track belt into the front part or into the rear part) on real time. Based on the sensed the user's real time location, without requiring the user's operation of the control panel, the apparatus for automatically controlling the speed of the track belt in accordance with the user's location on the track belt can be realized. Herein, it is effective that the resistances R1, R2 of all the strain gages are all the same with one another, because the sign of bridge voltage ΔV can be inverted whenever the user is biasedly located at the front part or at the rear part of the track belt, thereby easily sensing the user's location.

Also, when the user wishes to run faster on the track belt, the user is biasedly located at the front part of the track bell Herein, as the absolute value of the bridge voltage ΔV is changed in proportion to the user's bias on the track belt, the control unit controls the degree of acceleration or deceleration of the track belt in proportion to the absolute value of the bridge voltage ΔV.

In order to prevent the track belt from being erroneously controlled due to a so much sensitive control according to the user's location or movement, it is preferable not to change the speed of the track belt when the user is located within a preset range in the center of the track belt, but to change the speed of the track belt only when the user is biasedly located out of the preset range and moves his or her location on the track belt.

Also, the front load sensor and the rear load sensor are installed at right and left sides respectively thereby easily sensing the user's bias to the front or the rear direction, although the user has a propensity to biasedly walk or run in the left side or the right side on the track belt.

Right after starting the exercise on the track belt, in order to sense the user's propensity in terms of the location on the track belt, it is more preferable to operate the track belt for predetermined time without changing the speed of the track belt, to average the bridge voltage ΔV for the predetermined time, and to store the average bridge voltage as a reference bridge voltage ΔVref. This is to control the speed of the track belt considering the user's habitual preferred location on the track belt during the exercise. For example, when a user has a propensity to walk or run on the track belt a little bit front part on the track belt, although the user is a little bit biasedly located in front part of the track belt during the exercise, as the user's propensity is already reflected by the reference bridge voltage ΔVref, unless the user is more biasedly located to the front part of the track belt, the control unit does not control the track belt to accelerate.

The front load sensor(s) and the rear load sensor(s) are installed in contact with a frame which supports a deck located between the upper and the lower faces of the track belt. Here, the deck also supports loads or impacts from the user. That is, the front load sensor and the rear load sensor can be installed respectively between the frame and the deck. In addition, the load can be measured by inferring the measured deflection of the frame which supports the deck.

On the other hand, the present invention provides a speed control method for a treadmill including an endlessly rotating track belt, a driving unit for driving the track belt comprising: a step of measuring loads due to the weight of a user on the track belt at least one front part of the track belt and at least one rear part of the track belt; a step of averaging the measured values at the front part of the track belt and at the rear part of the track belt for preset time so as to recognize the location propensity of the user on the track belt; a step of sensing the location of the user on the track belt by comparing the measured values at front part of the track belt and at rear part of the track belt; and a step of controlling the speed of track belt to accelerate when the user is sensed as being located at the front part of the track belt and to decelerate when the user is sensed as being located at the rear part of the track belt.

Similarly, the load in accordance with the user's location is measured by a pair of front strain gages and a pair of rear strain gages having the same resistance with one another wherein the pair of the front strain gages and the pair of the rear strain gages constitute a wheatston bridge in which the front strain gages face each other and the rear strain gages face each other. Therefore, the control unit controls the speed of the track belt in accordance with the sign and the absolute value of the bridge voltage ΔV between the two points between the front strain gage and the rear strain gage.

On the other hand, the present invention provides a speed control apparatus for a treadmill having a deck, a track belt of endlessly rotating on the upper and the bottom face of the deck, and a driving unit for driving the track belt comprising: at least one front load sensor in the front part of the track belt and at least one rear sensor in the rear part of the track belt for sensing the location of a user on the track belt; whereby the location of the user on the track belt is sensed by comparing the measured values of the sensors, and the speed of the track belt is accelerated when the user move forward on the track belt and is decelerated when the user move backward on the track belt.

That is, based on the user's habit on the track belt that a user moves forward when the user wishes to run faster and that a user moves backward when the user wishes to run slower, by comparing the measured values from the load sensors with one another and sensing the user's real time location on the track belt, the speed of the track belt is controlled to be accelerated when the user moves forward and to be decelerated when the user moves backward.

This control is to realize the speed control of the track belt in accordance with the user's real time intention whether the user wishes to run faster or to run slower. Also, in case that a user wishes to change the staying location on the track belt during the exercise, as the speed of the track belt is not accelerated even though the user is biasedly located at the front part of the track belt, this control itself properly reflects the user's intention of only changing the staying location thereon.

Herein, all said front load sensor and said rear load sensor are not limited to means of independently measuring load, but includes a sensor(s) to measure a load by combining the front load sensor with rear load sensor.

Also, the measured values from the front load sensor and the rear load sensor are respectively averaged for a unit time, and then a difference is calculated in accordance with time by subtracting the present average value from the previous averaged one. In case that, after the absolute value of the difference maintains bigger than a preset criterion A, the absolute value of the difference becomes smaller than the preset criterion A, it is regarded that the user finishes forward or backward movement and stays within a predetermined range on the track belt. At this time, in case that the speed of the track belt is being accelerated, the speed of the track belt is decelerated for an instance, to the contrary, in case that the speed of the track belt is being decelerated, the speed of the track belt is accelerated for an instance. Herein, the preset criterion can be a preset value ΔFset based on the measured load, or can be a preset value ΔVset based on the bridge voltage in the wheatston bridge circuit, or can be preset value which can be converted therefrom. Further, the preset criterion can be preset before an exercise or during an exercise.

That is, at the moment that a user finishes movement on the track belt, as the user tends to continuously move in the previous direction due to the inertia force, by instantly reverse acceleration or deceleration is applied to the user, the user does not experience this unintended bias caused by the previous movement on the track belt.

The sensing of user's real time movement is realized by observing the difference obtained by subtracting present averaged measured value for a unit time from the previous measured one. Concretely, for the unit time Δt in which the movement of the user's center of gravity can be sensed, the measured values from the front and the rear load sensor are continuously averaged in real time in accordance with a shorter period (less than Δt), and the difference is calculated in real time by subtracting the later average from the earlier averaged one, and thus, if the difference becomes bigger than the preset criterion A, it is noticed that the user starts moving until the difference becomes smaller than the preset criterion A.

On the other hand, in order to achieve the same object but not to cause a possible impact to the user, in case that, after the absolute value of the difference maintains bigger than a preset criterion A, the absolute value of the difference becomes smaller than the preset criterion A, it is regarded that the user finishes forward or backward movement and stays within a predetermined range on the track belt, and thus, at this time, in case that the speed of the track belt was being accelerated, the acceleration degree of the track belt is lowered for an instance, to the contrary, in case that the speed of the track belt was being decelerated, the deceleration degree of the track belt is lowered for an instance.

The present invention also provides a speed control apparatus for treadmill including a deck, a track belt of endlessly rotating on the upper and the bottom face of the deck, and a driving unit for driving the track belt comprising: an accelerating area set at the front part on the track belt for accelerating the speed of the track belt when a user is located at the accelerating area; a decelerating area set at the rear part on the track belt for decelerating the speed of the track belt when the user is located at the decelerating area; and at least one front load sensor located at the front part of the track belt and at least one rear load sensor located at the rear part of the track belt for sensing the location of the user on the track belt, wherein the location of the user is sensed by comparing the measured values from the front load sensor and of the rear load sensor, and thus, the track belt is accelerated when the user is on the accelerating area and the track belt is decelerated when the user is on the decelerating area.

Through setting the accelerating area and the decelerating area on the track belt by a manufacturer or a user, not by a user's finger-operation, the user can accelerate the track belt by moving onto the accelerating area and can decelerate the track belt by moving onto the decelerating area.

Herein, in order to provide a user with a stable constant speed environment, a constant speed area set at the middle part on the track belt for maintaining the speed of the track belt when the user is located at the constant speed area is further comprised.

That is, in order to prevent the track belt from being erroneously controlled due to a so much sensitive control, it is preferable not to change the speed of the track belt when the user is located within a preset range in the middle of the track belt but to change the speed of the track belt only when the user is biasedly located out of the preset range.

Also, it is also effective that the accelerating area and the decelerating area are divided into plural areas respectively, and therefore, if a user is located on the divided areas of the accelerating area, the degree of acceleration is differently set in accordance with the divided areas. Similarly, if a user is located on the divided areas of the decelerating area, the degree of deceleration is differently set in accordance with the divided areas. Accordingly, as a user is more biasedly located on the track belt, the user can make the speed of the track belt more promptly reach a targeted speed. Herein, the divided area is not limited to form an area by defining the area with a definite boundary. Rather, the meaning of the divided area includes that the acceleration degree and the deceleration degree are continuously converted in proportion to the degree of the user's bias although the degree thereof is not converted in any boundary therebetween. Herein, the bias is expressed as the load difference ΔF or the bridge voltage ΔV.

Generally, regardless of the user's location on the track belt, considering the user's intention on the track belt, if a user moves forward, the user is regarded as having an intention to accelerate the user's running speed, similarly, if a user moves backward, the user is suspected as having an intention to decelerate the user's running speed. Therefore, although the user is not located on the accelerating area, it is desirable to accelerate the track belt when the user is sensed to move forward on the track belt during the user's forward movement, and similarly to decelerate the track belt when the user is sensed to move backward on the track belt during the user's backward movement.

Also, the measured value from the front load sensor and the rear load sensor are respectively averaged for a unit time, and then a difference is calculated in accordance with time by subtracting the present average value from the previous averaged one. In case that, after the absolute value of the difference maintains bigger than a preset criterion A, the absolute value of the difference becomes smaller than the preset criterion A, it is regarded that the user finishes forward or backward movement and stays within a predetermined range on the track belt. At this time, in case that the speed of the track belt is being accelerated, the speed of the track belt is decelerated for an instance, to the contrary, in case that the speed of the track belt is being decelerated, the speed of the track belt is accelerated for an instance.

Thereafter, if the user stays on the accelerating area on the track belt, the speed of the track belt is accelerated, and if the user stays on the constant speed area on the track belt, the speed thereof is maintained, and if the user stays on the decelerating area on the track belt, the speed thereof is decelerated.

Herein, when the user operates the control panel so that any signal is input to the control panel, the speed and the inclination of the track belt is maintained for a pre-determined time with the condition at the time when the signal was input. By being equipped with the above function, although a user does not have any necessity to operate the control panel during walking or running, in case that the user wishes to change the exercise condition such as a running course or an inclination of the track belt, the possibility to loss the user's balance can be fundamentally prevented. As the predetermined time for maintaining its exercise condition is enough for a user to operate the control panel, after the signal input via the control panel is terminated, the exercise condition of the treadmill is maintained without being changed for 1 or 2 seconds.

The acceleration or deceleration of the track belt is realized only when the differences of the measured values from the front and the rear load sensors exceeds the preset criterion A, whereby the slight bias of the user's location on the track belt may not cause the control for accelerating or decelerating the track belt speed against the user's intention.

Herein, the front load sensor and the rear load sensor are formed as a load cell respectively which can independently measure the load at its each position thereby catching the user's location and movement from the difference of the measured value. Here, so as to measure the load which the user applies to the deck, the front load sensor and the rear load sensor are installed between the deck and the frame supporting the deck.

Herein, when the user on the track belt runs faster than the proceeding speed of the track belt and thus is located at the front part thereof, the bridge voltage ΔV is also changed in proportion to the user's bias on the track belt. Therefore, the control unit controls the speed of the track belt in accordance with the bridge voltage ΔV. Based on the change of the average bridge voltage ΔVavg for a constant time Δt, the change of the user's location between the present and the just before can be caught.

Also, the front load sensor and the rear load sensor are installed at the left and at the right side respectively, thereby compensating the user's propensity of biasedly located exercising in the left or the right direction and catching the user's location. Therefore, in case of not considering the reference bridge voltage ΔVref, whether the track belt is to be accelerated or be decelerated by the driving unit is decided by the sign of the average bridge voltage ΔVavg, and the degree of the acceleration and the deceleration is decided by the absolute value of the average bridge voltage ΔVavg.

In case of considering the reference bridge voltage ΔVref, whether the track belt is to be accelerated or be decelerated by the driving unit is decided by the sign of the difference between average bridge voltage ΔVavg and the reference bridge voltage ΔVref, and the degree of the acceleration and the deceleration is decided by the absolute value of the difference between average bridge voltage ΔVavg and the reference bridge voltage ΔVref.

As the front load sensor and the rear load sensor measure the load which is transferred via the deck and thus are not revealed to the outside, the sensors can reliably and stably measure the load for a long time.

On the other hand, the present invention also provides a speed control method for a treadmill including a deck, a track belt of endlessly rotating on the upper and the bottom face of the deck, and a driving unit for driving the track belt which comprises: a step of measuring loads ΔF, ΔV at points of at least one front part of the track belt and of at least one rear part of the track belt which are delivered via the deck from the user; a step of catching the user's movement by comparing the measured loads at points of at least one front part of the track belt and of at least one rear part of the track belt; a step of controlling the track belt to accelerate while the user moves forward or to decelerate while the user moves backward.

Herein, a step of averaging the measured load for predetermined time at front and rear part of the track belt from the user so as to catch the user's location according to the user's propensity; a step of setting the area to include the user's averaged location for the predetermined time as a constant speed area, of setting the area in front of the constant speed area as an accelerating area, and of setting the area in rear of the constant speed area as a decelerating area are further comprised.

The step of catching the user's movement is realized by averaging the measured load F1 or R1 at the front part and the measured load F2 or R2 at the rear part for a unit time Δt, and by deciding whether the user moves forward or moves backward when the sign of the difference between the average value and the preset criterion i.e., A or ΔFset or ΔVset becomes bigger than the preset criterion.

After controlling the track belt to be accelerated or to be decelerated, an instant hesitant step of instantly reducing the degree of accelerating the track belt when the user finishes the forward movement and stays at on the track belt, or of instantly reducing the degree of decelerating the track belt when the user finishes the backward movement on the track belt, thereby preventing the user's bias due to the user's inertia.

Thereafter, if the user stays on the accelerating area on the track belt the speed of the track belt is accelerated, and if the user stays on the constant speed area on the track belt the speed thereof is maintained, and if the user stays on the decelerating area on the track belt the speed thereof is decelerated. Therefore, it is possible to prevent the user from being biased due to the user's inertia and also to continuously control the proceeding speed of the track belt.

Herein, when the user operates the control panel and any signal is input from the control panel, the exercise condition of the treadmill at the time when the signal was input is maintained for a few seconds so as not to cause the user to lose the balance on the track belt.

Also, the present invention also includes a step of stopping the track belt when the user is sensed to be located at the too rear part of the track belt from the comparison of the measured value at the front part of the track belt with the measured value at the rear part thereof. This is to guarantee the safety of users by automatically stopping the proceeding operation of the track belt, when a novice at exercising on the treadmill is too much biasedly pushed at the rear part of the track belt.

Also, the present invention provides a speed control method for a treadmill including a deck, a track belt of endlessly rotating on the upper and the bottom face of the deck, and a driving unit for driving the track belt which comprises: a step of measuring loads at points of at least one front part of the track belt and of at least one rear part of the track belt which are delivered via the deck from the user; a step of sensing the user's movement and/or user's location by comparing the measured loads at points of at least one front part of the track belt and of at least one rear part of the track belt; a step of stopping the track belt when the change of the measured loads in accordance with time is within the preset range.

That is, when there is not any change of load which is delivered via the deck, as it is regarded that the user got off the treadmill without stopping the track belt, the track belt is obligatorily stopped thereby preventing a user from being damaged when the user unconsciously gets on the treadmill.

Herein, whether there is any change of load from a user is sensed by whether the change of the measured values from the load sensors exceeds the preset value. As the preset value is set considering the measurement error, the preset value is much smaller than the preset criterion A, or ΔFset or ΔVset which is set for catching the user's movement.

On the other hand, the present invention provides a treadmill capable of measuring the user's weight which comprises: a frame; a deck placed on the frame; a track belt of endlessly rotating on the upper face and the bottom face of the deck; a wheatston bridge circuit including a pair of front strain gages installed on a front member between the frame and the deck at the front part of the track belt and a pair of rear strain gages installed on a rear member between the frame and the deck at the rear part of the track belt wherein the front and the rear strain gages face each other respectively; a weighing place indicator for guiding the user to stand thereon which is separately located from the center of the front strain gages and the rear strain gages;

and a weight indicator showing the user's weight from the wheatston bridge circuit. Though the treadmill, without being equipped with a weighing device, when a user only gets on the weighing place on the track belt, the user can weigh the user's weight. The measuring method of the user's weight can be obtained by the equation which express the relationship between the weighing place on the track belt and the bridge voltage ΔV.

Meanwhile, the present invention also provides a speed control apparatus for a treadmill including an endlessly rotating track belt, a driving unit for driving the track belt comprising: a plurality of front load sensors located at the front part of the track belt for measuring a load from a user on the track belt; a plurality of rear load sensors located at the rear part of the track belt for measuring a load from the user on the track belt; and a control unit for controlling the driving unit to accelerate or decelerate the speed of the track belt based on the measured values of the front load sensor and the rear load sensor.

By sensing the user's location from the measured values from the load sensors and by controlling the driving unit to accelerate or decelerate the proceeding speed of the track belt, the proceeding speed of the track belt can be automatically controlled in accordance with the user's running or walking speed, even though the user does not operate the control panel during the exercise.

The control unit controls the driving unit to raise the degree of acceleration as the value measured from the forefront load sensor is higher, and similarly, the control unit controls the driving unit to raise the degree of deceleration as the value from the rearest load sensors is higher. It is because the measured value of the forefront load sensor is sensitively higher when a user is biasedly located at the front part of the track belt, and also because the measured value of the rearest load sensor is sensitively higher when a user is biasedly located at the rear part of the track belt.

The front load sensors and the rear load sensors can be at least one load cell respectively. Also, the front load sensors and the rear load sensors can be at least one pair of front strain gages and at least one pair of rear strain gages respectively, in which a pair of the front strain gages and a pair of the rear strain gages constitute a wheatston bridge respectively.

In case that each of load sensors is formed as a pair of strain gages, a front strain gage of each of the front load sensors is installed at the right-front part of the track belt and the other front strain gage of each of the front sensors is installed at the left-front part of the track belt, and further, a rear strain gage of each of the rear load sensors is installed at the right-rear part of the track belt and the other rear strain gage of each of the rear sensors is installed at the left-rear part of the track belt, in which a pair of front strain gages and the rear strain gages constitute a wheatston bridge respectively so that the front strain gages may face each other in the wheatston bridge circuit and the rear strain gages may face each other therein. Therefore, by observing the bridge voltage ΔV of each of the wheaton bridges, the user's location in addition to movement can be sensed.

With this construction with the resistance R1 of the front strain gage and the resistance R2 of the rear strain gage, the bridge voltage ΔV is expressed as the above equation 1.

Accordingly, in case that the circuit has 3 wheatston bridges each of which has a pair of front strain gages having resistances of R11, R12, R13 in order from the forefront one and a pair of rear strain gages having a resistance of Ro when the supplied voltage to the wheatston bridge is V, each of the bridge voltage ΔV1, ΔV2, ΔV3 is expressed as following equations. Herein, as the rear strain gages are exemplified as being formed at the same location, the resistances of 6 rear strain gages are expressed as the same one Ro.

$\begin{array}{cc}\Delta V1=V\frac{\mathrm{Ro}-R11}{\mathrm{Ro}+R11}& \mathrm{Equation}2\\ \Delta V2=V\frac{\mathrm{Ro}-R12}{\mathrm{Ro}+R12}& \mathrm{Equation}3\\ \Delta V3=V\frac{\mathrm{Ro}-R13}{\mathrm{Ro}+R13}& \mathrm{Equation}4\end{array}$

Therefore, as the resistance R11 of the forefront one of the front strain gages becomes higher when the user is more biasedly located at the front part of the track belt, and as the resistance R13 of the rearest one of the front strain gages becomes higher when the user is more biasedly located at the rear part of the track belt, the user's location and movement can be easily and precisely caught by the sign and the absolute value of the bridge voltages ΔV1 to ΔV3. Through this construction, even though a user does not directly operate the control panel generally in front of the track belt, the proceeding speed of the track belt can be automatically adjusted by controlling the driving unit. Herein, as the sign of the bridge voltage ΔV is converted in accordance with the user's location of the front part thereof or the rear part thereof when the strain gages Ro, R11, R12, and R13 have the same resistance value, it is desirable that the strain gages Ro, R11, R12, and R13 also have the same resistance value in view of the easiness of the speed control.

Also, in view that a user is more biased located at the front part of the track belt when a user runs faster than the proceeding speed of the track belt, and that the bridge voltage ΔV1 to ΔV3 is also changed in accordance with the user's bias, the control unit controls the degree of acceleration or deceleration in proportion to the absolute value of the bridge voltage ΔV1 to ΔV3.

In order to prevent the proceeding speed of the track belt from being erroneously controlled due to a so much sensitive control according to the user's location or movement, it is preferable not to change the speed of the track belt when the user is located within a preset range of the center on the track belt but to change the speed of the track belt only when the user is biasedly located out of the preset range.

Also, in order to obtain the reliable control even when some of strain gages are out of order, with excluding the maximum and minimum bridge voltage from the bridge voltages ΔV1, ΔV2, ΔV3, . . . , the speed of the track belt can be controlled based on the sign and the absolute value of the rest of the bridge voltages.

Herein, as each of the bridge voltage ΔV1, ΔV2, ΔV3, . . . can be measured in real time, instead of controlling the speed of the track belt only based on the average bridge voltage ΔVavg, by controlling the speed of the track belt based on ΔV1 or ΔV3 including the forefront one of the front strain gages and the rearest one of the front strain gages, the proceeding speed of the track belt in accordance with the user's movement can be promptly controlled. Therefore, compared with an apparatus having only a pair of front strain gages and a pair of rear strain gages, the apparatus having plural pairs of front and rear strain gages can control the proceeding speed of the track belt more precisely and promptly with quick response time.

The front load sensors and the rear load sensors are installed in contact with the frame which supports the deck located between the upper and the lower faces of the track belt. Here, the deck also supports loads or impacts from the user. That is, each of the front load sensors and the rear load sensors can be installed between the frame and the deck. In addition, the load can be measured by inferring from the measured deflection of the frame which supports the deck considering the material property of the frame.

On the other hand, the present invention provides a A speed control method for a treadmill including an endlessly rotating track belt, a driving unit for driving the track belt comprising: a step of measuring loads due to the weight of a user on the track belt at different plural front parts of the track belt and at one rear part of the track belt; a step of sensing the location of the user on the track belt by comparing the measured values at front parts of the track belt and at the rear part of the track belt; and a step of controlling the speed of track belt to be accelerated when the user is sensed as being located at a front part of the track belt and to be decelerated when the user is sensed as being located at a rear part of the track belt.

At this time, by controlling the driving unit based on the average measured value, even though any measurement error occurs at some of load sensor(s), as the measurement error is compensated with the average value, the proceeding speed can be controlled corresponding with the user's intention.

ADVANTAGEOUS EFFECTS

As explained above, the present invention provides a speed control apparatus for a treadmill including an endlessly rotating track belt, a driving unit for driving the track belt comprising at least one front load sensor located in the front part of the track belt for measuring a weight of a user on the track belt, at least one rear load sensor located in the rear part of the track belt for measuring a weight of the user on the track belt and a control unit for controlling the driving unit to accelerate or decelerate the speed of the track belt based on the measured values of the front load sensor and the rear load sensor.

Also, the front load sensor of the present invention is formed as at least one front strain gage and the rear load sensor is formed as at least one rear front strain gage so that an automatic speed control apparatus for a treadmill of the present invention can acquire price competitiveness.

The present invention can have more reliability as the malfunction due to misperception of the simple gesture as a sign of acceleration or deceleration has been removed by the mechanism to sense user's location measuring a load point of the user on the track.

The present invention provides a stable speed change control device avoiding drastic change of speed.

The present invention also provides comfortable exercise environment minimizing inertial force effect by the automatic speed control of a track belt.

The present invention provides stable speed control environment not to misperceive user's movement of user on a track belt for operating button on a control panel or grasping a hand purse as a sign to accelerate or decelerate a belt.

BRIEF DESCRIPTION OF THE DRAWINGS

Accordingly, the present invention will be understood best through consideration of, and reference to, the following Figures, viewed in conjunction with the Detailed Description of the Preferred Embodiment referring thereto, in which like reference numbers throughout the various Figures designate like structure and in which:

FIG. 1 is a diagram showing the structure of a treadmill in accordance with a first embodiment.

FIG. 2 is a diagram illustrating the structure of a treadmill in accordance with other embodiments.

FIG. 3 is a separate perspective view of a track part of FIG. 1 and FIG. 2.

FIG. 4 is an expanded view illustrating part ‘A’ of FIG. 3.

FIG. 5 is a separated perspective view of a load sensor module of FIG. 4.

FIG. 6 is a cross sectional view from the low side illustrating a track part without a track belt of FIG. 1 and FIG. 2.

FIG. 7 is an expanded view showing part ‘B’ of FIG. 6.

FIG. 8 is a circuit diagram using a load sensor of FIG. 1.

FIG. 9 is a diagram for the operation principle of FIG. 1.

FIG. 10 is a figure illustrating a sectioned accelerating area, a constant speed area and a sectioned decelerating area on the track of FIG. 2.

FIG. 11 is a diagram for a primary operation principle of FIG. 2.

FIG. 12 is a figure illustrating the change of speed in accordance with user's movement from a constant speed area to an accelerating area and from the accelerating area to the constant speed area on the track belt.

FIG. 13 is a figure illustrating the change of speed in accordance with user's movement from a constant speed area to a decelerating area and from the decelerating area to the constant speed area on the track belt.

FIG. 14 is a figure illustrating another change of speed in accordance with user's movement from a constant speed area to an accelerating area and from the accelerating area to the constant speed area on the track belt.

FIG. 15 is a figure illustrating another change of speed in accordance with user's movement from a constant speed area to a decelerating area and from the decelerating area to the constant speed area on the track belt.

FIG. 16 is a cross sectional view showing the composition of a treadmill in accordance with third embodiment of the present invention.

FIG. 17 is a separate perspective view illustrating a track part of FIG. 16.

FIG. 18 is an expanded view of part ‘A’ of FIG. 17.

FIG. 19 is a perspective view from the low side illustrating a track part without a track belt of FIG. 16.

FIG. 20 is a figure showing a distribution of load sensors on a track belt of FIG. 15.

FIG. 21 is a separate perspective view of a front load sensor module of FIG. 19.

FIG. 22 is an expanded view showing part ‘B’ with a rear load sensor module of FIG. 19.

FIG. 23 is an expanded view showing part ‘C’ with a front load sensor module of FIG. 19.

FIG. 24 is a control circuit using load sensors of FIG. 16.

FIG. 25 is a diagram illustrating operation principle of FIG. 16.

BEST MODE FOR CARRYING OUT THE INVENTION

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. In describing the present invention, detailed description of laid-out function or structure is omitted in order to clarify the gist of the present invention.

As illustrated in FIG. 1 and FIGS. 3 to 9, a treadmill 100 equipped with an automatic speed control apparatus therefor of a first embodiment in accordance with the present invention comprises a track unit 110 for making the track belt 111 endlessly proceed so as to provide a user with exercise environment, a control panel unit 120 showing the operating speed and consumed calories in front of the track belt 111, load sensor module 190 for measuring a load delivered from the user at the front part of the track belt 111 and at the rear part of the track belt 111, and control unit (not shown) for controlling the track belt to be accelerated or decelerated based on the values measured by the load sensor module 190.

The track unit 110 includes an endlessly rotating track belt 111 to provide a user with a running or walking environment, a pair of rollers 112 for guiding the track belt 111 at the end part thereof, a driving unit 112a for driving the rollers 112 so as to rotate the track belt 111, a deck 113 formed as a plate located between the upper and lower faces of the track belt 111 so as to support weight or impact from the user, a frame 114 in contact with both right and left end sides of the deck 113 thereby supporting the deck 113, several cushion rubbers 115 installed between the deck 113 and the frame 114 so as to absorb impacts, a decoration cover 115 formed of metal material which covers both sides of the frame 114 not to reveal the frame 114 to the outside, support rollers 117 for supporting the front part of the treadmill 100, support member 118 for supporting the rear part of the treadmill 100.

As illustrated in FIG. 3, the track belt 111 is installed to endlessly rotate between the rollers 112, and the deck 113 is installed between the upper and lower faces of the track belt 111. Herein, both end sides of the deck 113 are placed on shaped members 114a protruded from the frame 114, and the cushion rubber 115 inserted between the deck member 114a and the deck 113 attenuates the impact load against the user's knees thereby protecting the user's knees.

The control panel unit 120 includes a control panel 121 for indicating the present proceeding speed, a run distance, consumed calories etc. and having lots of input buttons for ordering the walking or running or for controlling the inclination of the track belt 111, a pair of handle rod 122 protruded from the lower part of the control panel 121 for user's grasping during exercise or in emergency, connecting members 124 extended from the track unit 110 so that the control panel 121 can be located at the height of the user's waist, a parallel member connecting both of the connecting members 124 for reinforcing the transverse stiffness of the connecting members 124.

The load sensor module 190 is respectively installed at the front part and at the rear part of the track belt 111 so as to measure loads delivered via the deck 113 from the user. The load sensor module 190 includes medium members 191 transversely protruded from the frame 114, bending members 192 fixed to each of the medium members 191 for being appropriately bent by the load via the deck 113, strain gages 193a, 193b, 194a, and 194b attached on each of the bottom faces of the bending members 192, whereby the strain gages are deformed in accordance with the deformation of the bending members 192 within the elastic range thereof.

Herein, the medium member 191 and the bending member 192 are firmly combined by fastening means such as bolt's penetrating of the holes 191a, 192a when the members 191, 192 are folded, whereby the members 191, 192 are to be integrally deformed together with each other. The other hole 192b of the bending member 192 which is aligned with a hole of the cushion rubber 115 is used to combine the bending member 192 with the cushion rubber 115.

As illustrated in FIG. 8, the control unit includes a wheatston bridge which includes a pair of front strain gages 194a, 194b having resistance R2 for measuring load at the front part of the track belt 111 and a pair of rear strain gages 193a, 193b having resistance R1 for measuring load at the rear part of the track belt 111 wherein the pair of the front strain gages 194a, 194b face each other and the pair of the rear strain gages 193a, 193b face each other. Also, the control unit includes an amplifier for amplifying the bride voltage ΔV between a first point 181 and a second point 182 which is placed between the front strain gages 194a,194b and the rear strain gages 193a, 193b, an analog-digital converter for converting the amplified analog bridge voltage into digitalized bridge voltage for signal processing. That is, the control unit controls the driving unit 112a to accelerate or to decelerate the rotation of the rollers 112 thereby controlling the proceeding speed of the track belt 111.

At this time, when voltage V is applied to the wheatston bridge circuit, the bridge voltage ΔV between a first point 181 and a second point 182 is expressed as the fore-mentioned equation 1.

Therefore, when a user is biasedly located at the front part or the rear part of the track belt 111, the resistance of the strain gage installed at which the user is biasedly located is greater than one at which the user is not biasedly located. Therefore, the sign of bridge voltage ΔV is converted by whether the user is biasedly located at the front part or at the rear part of the track belt 111. Further, as the user is more biasedly located at any part of the track belt 111, the amount (i.e., absolute value) of the bridge voltage ΔV becomes greater, therefore, the degree of acceleration or deceleration is determined in proportion to the amount of the bridge voltage ΔV.

Herein, the front strain gages 194a, 194b and the rear strain gages 193a, 193b are formed as having the same resistance. However, any value of resistance such as 120Ω or 350Ω is acceptable.

Below, referring to FIG. 9, the operation principle of the automatic speed control apparatus of the first embodiment in accordance with the present invention is to be explained.

Firstly, the allowable range of a user's bias not to change the proceeding speed of the track belt is stored and preset in a form of the converted bridge voltage ΔVset (i.e., initial preset voltage) in the control unit.

Thereafter, when a user gets on the treadmill and pushes a start button on the control panel 121 to walk or run on the track belt, without automatically changing the speed of the track belt 111 for about 1 minutes, the load sensor module 190 measures the loads via the deck 113 from the user both at the front part of the track belt 111 and at the rear part of the track belt 111, whereby the user's propensity on whether the user likes to exercise at a little bit front part or rear part of the track belt 111 can be grasped. Concretely, for about one minute right after starting an exercise, average voltage of the measured bridge voltage ΔV of the wheatston bridge illustrated in FIG. 8 is stored as a reference bridge voltage ΔVref which is a criterion whether to change the proceeding speed of the track belt 111 or not.

Thereafter, when the user runs faster and becomes biasedly located at the front part of the track belt 111, as the bending member 192 at the front part thereof is deflected more than one at the rear part thereof, the resistance R2 of the front strain gages 194a, 194b becomes greater, however, the resistance R1 of the rear strain gages 193a, 193b is little changed because the bending member 192 at the rear part thereof is little bent. Therefore, according to the equation 1, the sign of the bridge voltage ΔV becomes minus (−), and the absolute value of the bridge voltage ΔV becomes greater as the user is more biasedly located on the track belt 111. At this time, when the absolute value of ΔV−ΔVref exceeds the initial preset voltage ΔVset, as the degree of the user's front bias exceeds the initial preset degree, even though any signal to accelerate is not input from the user, the control unit controls the proceeding speed of the track belt 111 to be accelerated in proportion to the absolute value of ΔV−ΔVref.

Similarly, when the user runs slower and becomes biasedly located at reart part of the track belt 111, as the bending member 192 at the rear part thereof is deflected more than one at the front part thereof, the resistance R1 of the rear strain gages 193a, 193b becomes greater, however, the resistance R2 of the front strain gages 194a, 194b is little changed because the bending member 192 at the rear part thereof is little bent. Therefore, according to the equation 1, the sign of the bridge voltage ΔV becomes plus (+), and the absolute value of the bridge voltage ΔV becomes greater as the user is more biasedly located on the track belt 111. At this time, when the absolute value of ΔV−ΔVref exceeds the initial preset voltage ΔVset, as the degree of the user's rear bias exceeds the initial preset degree, even though any signal to decelerate is not input from the user, the control unit controls the proceeding speed of the track belt 111 to be decelerated in proportion to the absolute value of ΔV−ΔVref.

Herein, whether to accelerate or to decelerate the proceeding speed of the track belt is determined by the sign of ΔV−ΔVref.

The automatic speed control continues until the user stops the exercise.

MODE FOR THE INVENTION

Hereinafter, a second embodiment of the present invention is to be explained.

As illustrated in FIGS. 2 to 8 and FIGS. 10 to 15, a treadmill 100 equipped with an automatic speed control apparatus therefor of a second embodiment in accordance with the present invention comprises a track unit 110 for making the track belt 111 endlessly proceed so as to provide a user with exercise environment, control panel unit 120 showing the operation speed and consumed calories in front of the track belt 111, load sensor module 190 for measuring load delivered from the user at the front part of the track belt 111 and at the rear part of the track belt 111, and a control unit (not shown) for controlling the track belt to be accelerated or decelerated based on the values measured by the load sensor module 190.

The track unit 110 includes an endlessly rotating track belt 111 to provide a user with a running or walking environment, a pair of rollers 112 for guiding the track belt 111 at the end part thereof, a driving unit 112a for driving the rollers 112 so as to rotate track belt 111, a deck 113 formed as a plate located between the upper and the lower faces of the track belt 111 so as to support weight or impact from the user, a frame 114 in contact with both right and left end sides of the deck 113 thereby supporting the deck 113, several cushion rubbers 115 installed between the deck 113 and the frame 114 so as to absorb impacts, a decoration cover 115 formed of metal material which covers both sides of the frame 114 not to reveal the frame 114 to the outside, support rollers 117 for supporting the front part of the treadmill 100, support member 118 for supporting the rear part of the treadmill 100.

As illustrated in FIG. 3, the track belt 111 is installed to endlessly rotate between the rollers 112, and the deck 113 is installed between the upper and lower faces of the track belt 111. Herein, both end sides of the deck 113 are placed on shaped members 114a protruded from the frame 114, and the cushion rubber 115 inserted between the deck member 114a and the deck 113 attenuates the impact load reacted to the user's knees thereby protecting the user's knees.

Herein, an accelerating area 151, I is formed at the front part of the track belt 111, and a constant speed area 152, II is formed at the middle part of the track belt 111, and a decelerating area 153, III is formed at the rear part of the track belt 111. That is, when a user is located at the accelerating area 151, I, the proceeding speed of the track belt is accelerated, and when a user is located at the constant speed area 152, II, the proceeding speed of the track belt is maintained, and when a user is located at the decelerating area 153, III, the proceeding speed of the track belt is decelerated.

As shown in FIG. 10, the accelerating area 151 is divided into a first accelerating area 151a located at the forefront part of the accelerating area 151, a second accelerating area 151b located at the middle part of the accelerating area 151, and a third accelerating area 151c located at the rearest part of the accelerating area 151. Therefore, when a user is located at the first accelerating area 151a, the speed of the track belt 111 is accelerated at the highest degree of acceleration. To the contrary, when a user is located at the third accelerating area 151c, the speed of the track belt 111 is accelerated at the lowest degree of acceleration.

Also, the decelerating area 153 located at just rear part of the constant speed area 152 is divided into a first decelerating area 153a located at the forefront part of the decelerating area 153, a second decelerating area 153b located at the middle part of the decelerating area 153, and a stop area 153c located at the rearest part of the decelerating area 153. Herein, when a user is located at the second decelerating area 153b, the speed of the track belt 111 is more promptly decelerated compared with when a user is located at the first decelerating area 153a. Also, when a user is located at the stop area, as it is regarded that the user is pushed into the rearest part of the track belt 111 due to an immature skill or being too exhausted, in order to guarantee the user's safety, the proceeding of the track belt is slowly stopped.

The control panel unit 120 includes a control panel 121 for indicating the present proceeding speed, a run distance, consumed calories etc. and having lots of input buttons for ordering the walking or running or for controlling the inclination of the track belt 111, a pair of handle rods 122 protruded from the lower part of the control panel 121 for user's grasping during exercise or in emergency, connecting members 124 extended from the track unit 110 so that the control panel 121 be located at the height of the user's waist, a parallel member connecting both of the connecting members 124 for reinforcing the transverse stiffness of the connecting members 124.

Herein, an hand pulse for measuring a user's pulse is installed on the surface of the connecting member 124.

The load sensor module 190 is respectively installed at the front part and at the rear part of the track belt 111 so as to measure loads delivered via the deck 113 from the user. The load sensor module 190 includes medium members 191 transversely protruded from the frame 114, bending members 192 fixed to each of the medium members 191 for being appropriately bent by the load via the deck 113, strain gages 193a, 193b, 194a, and 194b attached on each of the bottom faces of the bending members 192, whereby the strain gages are deformed in accordance with the deformation of the bending members 192 within the elastic range thereof.

Herein, the medium member 191 and the bending member 192 are firmly combined by fastening means such as bolt's penetrating of the holes 191a, 192a when the members 191, 192 are folded, whereby the members 191, 192 are to be integrally deformed together with each other. Other holes 192b of the bending member 192 which is aligned with a hole of the cushion rubber 115 is used to combine the bending member 192 with the cushion rubber 115.

As illustrated in FIG. 8, the control unit includes a wheatston bridge which a pair of front strain gages 194a, 194b having resistance R2 for measuring load at the front part of the track belt 111 and a pair of rear strain gages 193a, 193b having resistance R1 for measuring load at the rear part of the track belt 111 wherein the pair of the front strain gages 194a, 194b face each other and the pair of the rear strain gages 193a, 193b face each other. Also, the control unit includes an amplifier for amplifying the bride voltage ΔV between a first point 181 and a second point 182 which is placed between the front strain gages 194a,194b and the rear strain gages 193a, 193b, an analog-digital converter for converting the amplified analog bridge voltage into digital bridge voltage for signal processing. That is, the control unit controls the driving unit 112a to accelerate or to decelerate the rotation of the rollers 112 thereby controlling the proceeding speed of the track belt 111.

At this time, when voltage V is applied to the wheatston bridge circuit, the bridge voltage ΔV between a first point 181 and a second point 182 is expressed as the fore-mentioned equation 1.

Therefore, when a user is biasedly located at the front part or the rear part of the track belt 111, the resistance of the strain gage installed at which the user is biasedly located is greater than one at which the user is not biasedly located. Therefore, the sign of bridge voltage ΔV is converted by whether the user is biasedly located at the front part or at the rear part of the track belt 111. Further, as the user is more biasedly located at any part of the track belt 111, the amount (i.e., absolute value) of the bridge voltage ΔV becomes greater, therefore, the degree of acceleration or deceleration is determined in proportion to the amount of the bridge voltage ΔV.

Here, as the analog bridge voltage ΔV forms a sine wave, an error can occurs according to the measurement time. Therefore, it is necessary to average the bridge voltage ΔV for a unit time Δt for which the movement of a user's center of gravity can be sensed. Accordingly, the speed control apparatus of the present embodiment catches a user's movement based on the average bridge voltage ΔVavg for the unit time Δt.

Moreover, the front strain gages 194a, 194b and the rear strain gages 193a, 193b are formed as having the same resistance. However, any value of resistance such as 120Ω or 350Ω is acceptable.

Below, referring to FIG. 11, the operation principle of the automatic speed control apparatus of the second embodiment in accordance with the present invention is to be explained.

Firstly, the allowable range of a user's bias not to change the proceeding speed of the track belt is stored and preset in a form of the converted bridge voltage ΔVset (i.e., initial preset voltage) in the control unit.

Thereafter, when a user gets on the treadmill and pushes a start button on the control panel 121 to walk or run on the track belt, without automatically changing the speed of the track belt 111 for about 15 seconds, the load sensor module 190 measures the loads via the deck 113 from the user both at front part of the track belt 111 and at the rear part of the track belt 111, whereby the user's propensity on whether the user likes to exercise at a little bit front part or rear part of the track belt 111 can be grasped. Concretely, for about one minute right after starting an exercise, an average voltage of the measured bridge voltage ΔV of the wheatston bridge illustrated in FIG. 8 is stored as a reference bridge voltage ΔVref which is a criterion whether to change the proceeding speed of the track belt 111 or not.

Thereafter, in case that the user runs faster than the proceeding speed of the track belt 111 and thus the user is biasedly located at the front part of the track belt 111, the average bridge voltage ΔVavg for a unit time Δt, for which the movement of a user's center of gravity can be sensed, is continually or periodically obtained.

Thus, as the user moves forward or backward on the track belt, the average bridge voltage ΔVavg is continuously changed, and also, the difference ΔVavg−ΔVref between the average bridge voltage ΔVavg and the reference bridge voltage ΔVref is also changed. At this time, as controlling the speed of the track belt 111 only based on the difference ΔVavg−ΔVref may cause the unstable exercise environment, it is desirable to control the speed of the track belt 111 to be changed only when the difference ΔVavg−ΔVref exceeds the preset criterion A or AFset or ΔVset. That is, whether the track belt to be accelerated or to be decelerated is determined by the sign of the difference ΔVavg−ΔVref, and the degree of the acceleration or deceleration is determined by the absolute value of the difference ΔVavg−ΔVref.

Accordingly, when the absolute value of the difference ΔVavg−ΔVref exceeds the initial preset criterion ΔVset, it is regarded that the user is moving on the track belt 111. Thus, if the user is moving forward, the track belt is controlled to be accelerated, and if the user is moving backward, the track belt is controlled to be decelerated.

When a user moves forward over the initially preset range, as the bending member 192 at the front part thereof is deflected more than one at the rear part thereof, the resistance R2 of the front strain gages 194a, 194b becomes greater, however, the resistance R1 of the rear strain gages 193a, 193b is little changed because the bending member 192 at the rear part thereof is little bent. Therefore, according to the equation 1, the sign of the bridge voltage ΔVavg becomes minus (−), and the absolute value of the bridge voltage ΔVavg becomes greater as the user is more biasedly located on the track belt 111. At this time, as the absolute value of ΔVavg−ΔVref exceeds the initial preset voltage ΔVset, even though any signal to accelerate is not input from the user, the control unit controls the proceeding speed of the track belt 111 to be accelerated in proportion to the absolute value of ΔVavg−ΔVref.

Similarly, when a user moves forward over the initially preset range, as the bending member 192 at the rear part thereof is deflected more than one at the front part thereof, the resistance R1 of the rear strain gages 193a, 193b becomes greater, however, the resistance R2 of the front strain gages 194a, 194b is little changed because the bending member 192 at the rear part thereof is little bent. Therefore, according to the equation 1, the sign of the bridge voltage ΔV becomes plus (+), and the absolute value of the bridge voltage ΔVavg becomes greater as the user is more biasedly located on the track belt 111. At this time, as the absolute value of ΔVavg−ΔVref exceeded the initial preset voltage ΔVset, even though any signal to decelerate is not input from the user, the control unit controls the proceeding speed of the track belt 111 to be decelerated in proportion to the absolute value of ΔVavg−ΔVref.

To the contrary, when the absolute value of the difference ΔVavg−ΔVref is smaller than the initially preset criterion ΔVset, it is sensed that the user does not move on the track belt. In this case, when the user is located on the accelerating area 151, the track belt 111 is controlled to be accelerated, and when the user is located on the constant speed area 152, the track belt 111 is controlled to be maintained with a constant speed, and when the user is located on the decelerating area 153, the track belt 111 is controlled to be decelerated.

At this time, which area the user is located at can be sensed by the difference ΔVavg−ΔVref.

Herein, when a user moves from the constant speed area 152 to the accelerating area 151 or from the accelerating area 151 to the decelerating area 153, as the direction of the user's movement coincides with the direction of the velocity vector of the track belt, the user tends to be biased due to the inertia against the user's intention. Further, considering that the inertia is maximized when a user stops his or her movement, it is effective to instantly apply an acceleration or deceleration pattern which is opposite to the user's movement at the time when the user finishes a forward or backward movement (i.e., when the absolute value of the difference ΔVavg−ΔVref exceeds the initially preset criterion ΔVset) thereby preventing the user's being biased against the user's intention.

When a user moves forward so as to directly operate the control panel 121, the user is generally located at the front part of the track belt 111. In this case, as the user did not intend to run faster, accelerating the track belt makes the user feel uncomfortable. Therefore, in case that any signal is input from the control panel 121, the operation condition such as the proceeding speed and the inclination of the track belt 111 is constantly maintained for the time being.

Also, in case that a user is pushed to be located at the rearest part of the track belt 111, in order to guarantee the user's safety, the control unit 120 stops the operation of the driving unit 112a.

The automatic speed control continues until the user stops the exercise.

Below, referring to FIGS. 12 and 13, a first operation example in accordance with the automatic speed control apparatus for a treadmill is to be explained. The first operation example is to remove the use's unintentional bias by applying the acceleration or deceleration pattern which is opposite to the user's movement direction at the time when the user finishes his or her movement.

FIG. 12 shows a diagram 201 of the user's location in accordance with time (the right longitudinal axis) and a diagram 301 of the speed of the track belt in accordance with time when a user moves from a constant speed area to an accelerating area and then from the accelerating area to the constant speed area on the track belt 111.

As long as a user stays at the constant speed area 152 (˜t1), the track belt is also controlled to run at a constant speed. In case that the user starts to move from the constant speed area 152 to the acceleration area 151 (t1˜t2), as it is regarded that the user wishes to run faster, although the user stays in the constant speed area 152, the track belt is controlled to be accelerated during the user's forward movement. Thereafter, when the user crosses into the accelerating area 151 (t2˜t3), the track belt 111 is controlled to be accelerated with the higher degree of acceleration.

In case that the user starts to stay at the accelerating area 151 (t3˜t4), in order to prevent the user from being biased due to the inertia force against the user's intention, the track belt 111 is controlled to be instantly decelerated. Thereafter, as the user is located at the accelerating area 151, the track belt is controlled to be accelerated with the predetermined acceleration in accordance with the accelerating area 151a, 151b, and 151c.

When the user starts to move backward from the accelerating area 151 (t4˜t5), as the user intends to run slower, although the user is located within the accelerating area 151, the track belt 111 is controlled to be decelerated with the low degree of deceleration. Also, even when the user reaches the constant speed area 152 (t5˜t6), the track belt 111 is controlled to be gently decelerated. At the time when the user finishes the backward movement and stays at the constant speed area 152, in order to prevent the user to be biased due to the inertia force against the user's intention, the track belt 111 is controlled to be instantly accelerated, and then, to be maintained at a constantspeed.

Herein, the instant deceleration at t3 and the instant acceleration at t6 are determined respectively by the degree of the acceleration just before t3 and the degree of deceleration just before t6, thereby effectively preventing the user's unintentional bias due to the inertia force.

FIG. 13 shows a diagram 202 of the user's location in accordance with time (right longitudinal axis) and a diagram 302 of the speed of the track belt in accordance with time when a user moves from a constant speed area to a decelerating area and then from the decelerating area to the constant speed area on the track belt 111.

As long as a user stays at the constant speed area 152 (˜t1), the track belt is also controlled to run at a constantspeed. In case that the user starts to move from the constant speed area 152 to the deceleration area 153 (t1˜t2), as it is regarded that the user wishes to run slower, although the user stays in the constant speed area 152, the track belt is controlled to be gently decelerated during the user's backward movement. Thereafter, when the user crosses into the decelerating area 153 (t2˜t3), the track belt 111 is controlled to be decelerated with the higher degree of deceleration.

In case that the user starts to stay at the decelerating area 153 (t3˜t4), in order to prevent the user from being biased due to the inertia force against the user's intention, the track belt 111 is controlled to be instantly accelerated. Thereafter, as the user is located at the decelerating area 153, the track belt is controlled to be decelerated with the predetermined acceleration in accordance with the decelerating area 153a, 153b. Herein, if the user is located at the rearest part of the track belt 111, i.e., a stop area 153c, the track belt 111 is controlled to be stopped.

When the user starts to move forward from the decelerating area 153 (t4˜t5), as the user intends to run faster, although the user is located within the decelerating area 153, the track belt 111 is controlled to be gently accelerated. Also, even when the user reaches the constant speed area 152 (t5˜t6), the track belt 111 is still controlled to be gently accelerated. At the time when the user finishes the forward movement and stays at the constant speed area 152, in order to prevent the user to be biased due to the inertia force against the user's intention, the track belt 111 is controlled to be instantly decelerated, and then, to be maintained at a constantspeed.

Herein, the instant acceleration at t3 and the instant deceleration at t6 are determined respectively by the degree of the deceleration just before t3 and the degree of acceleration just before t6, thereby effectively preventing the user's unintentional bias due to the inertia force.

Below, referring to FIGS. 14 and 15, a second operation example in accordance with the automatic speed control apparatus for a treadmill is to be explained. The second operation example is also to remove the use's unintentional bias by applying the lowered acceleration or lowered deceleration pattern which is the same with the user's movement direction at the time when the user finishes his or her movement.

FIG. 14 shows a diagram 201 of the user's location in accordance with time (right longitudinal axis) and a diagram 401 of the speed of the track belt in accordance with time when a user moves from a constant speed area to an accelerating area and then from the accelerating area to the constant speed area on the track belt 111.

The control pattern of the second operation example from t1 to t3 is the same to the above-described first operation example referring to FIG. 12. However, the second operation example has an object to reduce the degree of impact which the user may feel uncomfortable at the time when the opposite pattern of acceleration or deceleration is instantly applied. Therefore, instead of applying the opposite pattern of acceleration or deceleration to the user's movement, the second operation example applies the alleviated acceleration or deceleration corresponding to the user's movement. Concretely, when the user starts to move backward from the accelerating area 151 (t4˜t5), as long as the user is located within the accelerating area 151, the track belt 111 is controlled to be accelerated with the lower degree of acceleration. Further, when the user reaches the constant speed area 152 (t5˜t6), the track belt 111 is controlled to be accelerated with the much lower degree of acceleration than that during t4˜t5. Further, when the user stays at the constant speed area 153 (t6˜), in order to prevent the user from being influenced by backward inertia force, the track belt 111 is controlled to be instantly accelerated. Herein, the degree of acceleration is lower than that at t6 of FIG. 12. Thereafter, as the user is located at the constant speed area, the track belt 111 is controlled to be uniformly maintained.

FIG. 15 shows a diagram 202 of the user's location in accordance with time (right longitudinal axis) and a diagram 402 of the speed of the track belt in accordance with time when a user moves from a constant speed area to a decelerating area and then from the decelerating area to the constant speed area on the track belt 111.

Similarly, the control pattern of the second operation example from t1 to t3 is the same to the above-described first operation example referring to FIG. 13. However, the second operation example has an object to reduce the degree of impact which the user may feel uncomfortable at the time when the opposite pattern of acceleration or deceleration is instantly applied. Therefore, instead of applying the opposite pattern of acceleration or deceleration to the user's movement, the second operation example applies the alleviated acceleration or deceleration corresponding to the user's movement. Concretely, when the user starts to move forward from the decelerating area 153 (t4˜t5), as long as the user is located within the decelerating area 153, the track belt 111 is controlled to be decelerated with the lower degree of deceleration. Further, when the user reaches the constant speed area 152 (t5˜t6), the track belt 111 is controlled to be decelerated with the much lower degree of deceleration than that during t4˜t5. Further, when the user stays at the constant speed area 153 (t6˜), in order to prevent the user from being influenced by forward inertia force, the track belt 111 is controlled to be instantly decelerated. Herein, the degree of deceleration is lower than that at t6 of FIG. 14. Thereafter, as the user is located at the constant speed area, the track belt 111 is controlled to be uniformly maintained.

The automatic speed control continues until the user stops the exercise

Hereinafter, a third embodiment of the present invention is to be explained.

As illustrated in FIGS. 16 to 25, a treadmill 100 equipped with an automatic speed control apparatus therefor of a first embodiment in accordance with the present invention comprises a track unit 110 for making the track belt 111 endlessly proceed so as to provide a user with exercise environment, control panel unit 120 showing the operating speed and consumed calories in front of the track belt 111, a load sensor module 190 for measuring load delivered from the user at the front part of the track belt 111 and at the rear part of the track belt 111, and a control unit (not shown) for controlling the track belt to be accelerated or decelerated based on the values measured by the load sensor module 190.

The track unit 110 includes an endlessly rotating track belt 111 to provide a user with a running or walking environment, a pair of rollers 112 for guiding the track belt 111 at the end part thereof, a driving unit 112a for driving the rollers 112 so as to rotate track belt 111, a deck 113 formed as a plate located between the upper and lower faces of the track belt 111 so as to support weight or impact from the user, a frame 114 in contact with both right and left end sides of the deck 113 thereby supporting the deck 113, several cushion rubbers 115 installed between the deck 113 and the frame 114 so as to absorb impacts, a decoration cover 115 formed of metal material which covers both sides of the frame 114 not to reveal the frame 114 to the outside, support rollers 117 for supporting the front part of the treadmill 100, support member 118 for supporting the rear part of the treadmill 100.

As illustrated in FIG. 17, the track belt 111 is installed to endlessly rotate between the rollers 112, and the deck 113 is installed between the upper and lower faces of the track belt 111. Herein, both end sides of the deck 113 are placed on shaped members 114a protruded from the frame 114, and the cushion rubber 115 inserted between the deck member 114a and the deck 113 attenuates the impact load against the user's knees thereby protecting the user's knees.

The control panel unit 120 includes a control panel 121 for indicating the present proceeding speed, a run distance, consumed calories etc. and having lots of input buttons for ordering the walking or running or for controlling the inclination of the track belt 111, a pair of handle rod 122 protruded from the lower part of the control panel 121 for user's grasping during exercise or in emergency, connecting members 124 extended from the track unit 110 so that the control panel 121 be located at the height of the user's waist, a parallel member connecting both of the connecting members 124 for reinforcing the transverse stiffness of the connecting members 124. However, the proceeding speed of the track belt is automatically controlled corresponding with the user's intention, a button for controlling the speed of the track belt 111 is not formed on the control panel 121.

The load sensor module 190 is respectively installed at the front part and at the rear part of the track belt 111 so as to measure loads delivered via the deck 113 from the user. The load sensor module 190 includes medium members 191 transversely protruded from the frame 114, bending members 192 fixed to each of the medium members 191 for being appropriately bent by the load via the deck 113, strain gages 171a-173b, 181a-183b attached on each of the bottom faces of the bending members 192, whereby the strain gages are deformed in accordance with the deformation of the bending members 192 within the elastic range thereof.

Herein, 6 front strain gage modules having a strain gage 181a, 182a,183a, 181b,181b,183b respectively are installed at the front part of the deck 113.

Specifically, 6 front strain gage modules are divided into 3 pairs of front strain gage modules (i.e., 181a-181b, 182a-182b, 183a-183b), and as illustrated in FIG. 20, each pair of front strain gage modules are installed at the right side and at the left side of different front parts of the track belt 111. On the contrary, 2 rear strain gage modules having 3 strain gages 171a-173a, 171b-173b respectively are installed at the rear part of the deck 113. Specifically, as illustrated in FIG. 20, 2 rear strain gage modules (i.e., 171a-173a, 171b-173b) are respectively installed at the right side and at the left side of the same rear part of the track belt 111. That is, each party including 3 rear strain gagaes 171a-173a or 171b-173b are attached parallel with one another on a bending member 192 and thus 3 rear strain gages 171a-173a or 171b-173b in a party are equally deflected and thus have the equal change of their resistances.

Also, the medium member 191 and the bending member 192 are firmly combined by fastening means such as bolt's penetrating of the holes 191a, 192a when the members 191, 192 are folded, whereby the members 191, 192 are to be integrally deformed together with each other. Other hole 192b of the bending member 192 which is aligned with a hole of the cushion rubber 115 is used to combine the bending member 192 with the cushion rubber 115.

As illustrated in FIG. 24, the control unit includes 3 wheatston bridges which consist of 3 pairs of front strain gages 181a-181b, 182a-182b, 183a-183b having resistance R11, R12, R13 respectively for measuring load with differently located at the front parts L1,L2,L3 of the track belt 111 and 3 pairs of rear strain gages 171a-171b, 172a-172b, 173a-173b having resistance R01, R02, R03 respectively for measuring load with located at the same rear part of the track belt 111 wherein the pair of the front strain gages 181a-181b, 182a-182b, 183a-183b face each other in each of the wheatston bridges and the pair of the rear strain gages 171a-171b, 172a-172b, 173a-173b face each other in each of the wheatston bridges. Also, the control unit includes an amplifier for amplifying the bride voltage ΔV1, ΔV2, ΔV3 between each of first points 161a, 162a, 163a and each of second points 161b, 162b, 163b which is placed between the front strain gages 181a, 181b, 182a, 182b, 183a, 183b and the rear strain gages 171a, 171b, 172a, 172b, 173a, 173b, an analog-digital converter for converting the amplified analog bridge voltage into digital bridge voltage for signal processing. That is, the control unit controls the driving unit 112a to accelerate or to decelerate the rotation of the rollers 112 thereby controlling the proceeding speed of the track belt 111.

At this time, when power voltage V is applied to each of the wheatston bridge circuits, each of the bridge voltages ΔV1, ΔV2, ΔV3 between each of the first points 161a, 162a, 163a and each of the second points 161b, 162b, 163b is expressed as the fore-mentioned equations 2 to 4.

Therefore, when a user is biasedly located at the front part or the rear part of the track belt 111, the resistance of the strain gages installed at which the user is biasedly located is greater than one at which the user is not biasedly located. Therefore, the sign of bridge voltage ΔV1, ΔV2, ΔV3 is converted by whether the user is biasedly located at the front part or at the rear part of the track belt 111. Further, as the user is more biasedly located at any part of the track belt 111, the amount (i.e., absolute value) of the bridge voltage ΔV1, ΔV2, ΔV3 becomes greater, therefore, the degree of acceleration or deceleration is determined in proportion to the amount of the bridge voltage ΔV1, ΔV2, ΔV3.

Herein, the front strain gages 181a, 181b, 182a, 182b, 183a, 183b and the rear strain gages 171a, 171b, 172a, 172b, 173a, 173b are formed as having all the same resistance.

However, any value of resistance such as 120Ω or 350Ω is acceptable.

Below, referring to FIG. 25, the operation principle of the automatic speed control apparatus of the third embodiment in accordance with the present invention is to be explained.

Firstly, the allowable range of a user's bias not to change the proceeding speed of the track belt is stored and preset in a form of the converted bridge voltage ΔVset (i.e., initial preset voltage) in the control unit. Herein, the initial preset voltage ΔVset is set based on the average value of each of bridge voltages ΔV1, ΔV2, ΔV3.

Thereafter, when a user gets on the treadmill and pushes a start button on the control panel 121 to walk or run on the track belt, without automatically changing the speed of the track belt 111 for about 10 seconds to 60 seconds, the load sensor module 190 measures the loads via the deck 113 from the user both at front part of the track belt 111 and at the rear part of the track belt 111, whereby the user's propensity on whether the user likes to exercise at a little bit front part or rear part of the track belt 111 can be grasped. Concretely, for about one minute right after starting an exercise, average voltage of the measured bridge voltages ΔV1, ΔV2, ΔV3 of the wheatston bridges illustrated in FIG. 24 is stored as a reference bridge voltage ΔVref which is a criterion whether to change the proceeding speed of the track belt 111 or not.

Thereafter, when the user runs faster and becomes biasedly located at front part of the track belt 111, as the bending member 192 at the forefront part thereof is deflected more than other ones at the front part thereof, the resistance R11 of the forefront strain gages 181a, 181b becomes greatest, however, the resistance R01, R02, R03 of the rear strain gages 171a, 171b, 172a, 172b, 173a, 173b is little changed because the bending member 192 at the rear part thereof is little bent. Therefore, according to the equations 2 to 4, the sign of the bridge voltage ΔV1, ΔV2, ΔV3 becomes minus (−), and the absolute value of the bridge voltage ΔV1, ΔV2, ΔV3 becomes greater as the user is more biasedly located on the track belt 111. That is, the absolute value of ΔV1 becomes greater than the absolute value of ΔV3. At this time, if the average value of ΔV1, ΔV2, ΔV3 is put as ΔVavg, when the absolute value of ΔVavg−ΔVref exceeds the initial preset voltage ΔVset, as the degree of the user's front bias exceeds the initial preset degree, even though any signal to accelerate is not input from the user, the control unit controls the proceeding speed of the track belt 111 to be accelerated in proportion to the absolute value of ΔVavg−ΔVref.

Similarly, when the user runs slower and becomes biasedly located at the rearer part of the track belt 111, as the bending member 192 at the forefront part thereof is deflected less than other ones at the front part thereof, the resistance R11 of the forefront strain gages 181a, 181b becomes smallest. Further, although the resistance R13 of the front strain gages 183a, 183b becomes smaller less than that of the forefront strain gages 181a, 181b because the bending member 192 at the rearest one of the front parts thereof is relatively more bent than that 192 at the forefront part thereof however is the relatively less bent comparing when the user stays in the center (i.e., more specifically, the preset range which does not cause the change of the proceeding speed of the track belt) of the track belt. Therefore, according to the equations 2 to 4, the sign of the bridge voltage ΔV1, ΔV2, ΔV3 becomes plus (+), and the absolute value of the bridge voltage ΔV1, ΔV2, ΔV3 becomes greater as the user is more biasedly located on the track belt 111. At this time, when the absolute value of ΔVavg−ΔVref exceeds the initial preset voltage ΔVset, as the degree of the user's rear bias exceeds the initial preset degree, even though any signal to decelerate is not input from the user, the control unit controls the proceeding speed of the track belt 111 to be decelerated in proportion to the absolute value of ΔVavg−ΔVref.

Herein, the degree of acceleration or deceleration of the track belt 111 is set based on the absolute value of ΔV1−ΔVref or ΔV3−ΔVref.

On the other hand, instead of controlling the proceeding speed of the track belt based on the average voltage ΔVavg of averaging all bridge voltages ΔV1, ΔV2, ΔV3, when the circuit has more than 3 wheatston bridges, excluding wheatston bridges including the forefront strain gage and/or the rearest strain gage, based on the average voltage of averaging the rest of bridge voltages, the track belt can be controlled to be accelerated or decelerated. In this case, the degree of acceleration or deceleration of the track belt 111 is set based on the absolute value of a difference between a bridge voltage having a secondly forefront strain gage and the reference bridge voltage or a difference between a bridge voltage having a secondly rearest strain gage and the reference bridge voltage.

Herein, whether to accelerate or to decelerate the proceeding speed of the track belt is determined by the sign of ΔVavg−ΔVref.

The automatic speed control continues until the user stops the exercise.

INDUSTRIAL APPLICABILITY

As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.

That is, the exemplary embodiment of present invention has explained with two strain gages as a pair formed to at least one side of the front or the rear part of the track belt. However, the present invention also includes a track belt formed with strain gage on the left side and the right side of the front part and the left side and right side of the rear part respectively.

Also, the exemplary embodiment includes a load sensor module located between a deck 113 and a frame 114, but the present invention also can calculates a load from a different amount of the frame 114 by attaching a strain gage to a shaped deck support 114a of the frame 114 as a manner of user's location measurement.

As for sensing the user's location on the track, a step to catch user's exercise location suited to his or her tastes has been included, however this step can be excluded and, instead, the amount and the sign of bridge voltage difference ΔV can be used for the direct control of the speed of a track belt 111. In order to avoid excessive sensibility for deciding accelerating or decelerating, a treadmill of the present invention keeps initial value ΔVset without changing the speed when the absolute value ΔV of the said bridge voltage difference is less than a specific value, but it can be selectively applied. In this case, as the track belt is accelerated or decelerated in the condition of ΔVset and ΔV with having no initial value, the speed of the track belt is controlled by the absolute value of ΔV and the sign.

Claims

1. A speed control apparatus for a treadmill including a deck, a track belt of endlessly rotating on the upper and the bottom face of the deck, and a driving unit for driving the track belt comprising:

at least one front load sensor in the front part of the track belt for measuring load transferred via the deck which supports the user on the track belt; and

at least one rear load sensor in the rear part of the track belt for measuring load transferred via the deck which supports the user on the track belt;

wherein the location of the user on the track belt is sensed as being more biasedly located at the front part, as the measured value by the front load sensor is larger than the measured value by the rear load sensor; and wherein the location of the user on the track belt is sensed as being more biasedly located at the rear part, as the measured value by the rear load sensor is larger than the measured value by the front load sensor, and wherein the speed of the track belt is controlled in accordance with the location of the user on the track belt.

2. The speed control apparatus as claimed in claim 1, wherein the track belt is accelerated when the user locates at the front part of the track belt, and the track belt is decelerated when the user locates at the rear part of the track belt.

3. The speed control apparatus as claimed in claim 1, wherein the deck is supported at its both sides on the deck supports which is protruded from a frame of the treadmill; and wherein the front load sensor and the rear load sensor are located at the deck support for measuring the loads transferred via the deck.

4. The speed control apparatus as claimed in claim 1, wherein the front load sensor and the rear load sensor are formed as at least one load cell respectively.

5. A speed control apparatus for a treadmill including a deck, a track belt of endlessly rotating on the upper and the bottom face of the deck, and a driving unit for driving the track belt comprising:

at least one front strain gauge in the front part of the track belt for being deformed by the load transferred via the deck which supports the user on the track belt; and

at least one rear strain gauge in the rear part of the track belt for being deformed by the load transferred via the deck which supports the user on the track belt;

wherein the front strain gauge and the rear strain gauge comprises at least one wheatston bridge circuit; wherein the location of the user on the track belt is sensed by the bridge voltage of the wheatston bridge; and wherein the speed of the track belt is controlled in accordance with the location of the user on the track belt.

6. The speed control apparatus as claimed in claim 5, wherein the rear strain gauge and the front strain gauge have same resistance with each other.

7. The speed control apparatus as claimed in claim 5, wherein the track belt is accelerated when the user locates at the front part of the track belt, and the track belt is decelerated when the user locates at the rear part of the track belt.

8. The speed control apparatus as claimed in claim 5, wherein the driving unit controls the degree of the acceleration or the deceleration in accordance with the bridge voltage of the wheatston bridge circuit.

9. The speed control apparatus as claimed in claim 5, wherein the treadmill further includes a frame for supporting the deck; and wherein each of the front strain gauge and the rear strain gauge is attached on the surface of one of bending members which are protruded from the frame for supporting the deck so that the each of the strain gauges is integrally deformed with the each of the bending members.

10. The speed control apparatus as claimed in claim 8, wherein the allowable range of a user's bias not to change the speed of the track belt is stored and preset in a form of the initial preset voltage ΔVset; and wherein the speed of the track belt is changed only when the absolute value of the bridge voltage exceeds the absolute value of the initial preset voltage ΔVset.

11. The speed control apparatus as claimed in claim 10, wherein the averaged value of the measured bridge voltage ΔV of the wheatston bridge for a predetermined period right after starting an exercise is stored as a reference bridge voltage ΔVref, and wherein the speed of the track belt is changedly controlled by the difference between the bridge voltage ΔV and the reference bridge voltage ΔVref.

12. The speed control apparatus as claimed in claim 11, wherein the speed of the track belt is changedly controlled only when the absolute difference (ΔV−ΔVref) between the bridge voltage ΔV and the reference bridge voltage ΔVref exceeds the initial preset voltage ΔVset.

13. A speed control apparatus for treadmill including a deck, a track belt of endlessly rotating on the upper and the bottom face of the deck, and a driving unit for driving the track belt comprising:

an accelerating area set at the front part on the track belt for accelerating the speed of the track belt when a user is located at the accelerating area;

a decelerating area set at the rear part on the track belt for decelerating the speed of the track belt when the user is located at the decelerating area;

at least one front load sensor in the front part of the track belt for measuring load transferred via the deck which supports the user on the track belt; and

at least one rear load sensor in the rear part of the track belt for measuring load transferred via the deck which supports the user on the track belt;

wherein the location of the user is sensed by comparing the measured values from the front load sensor and of the rear load sensor, and thus, the track belt is accelerated when the user is on the accelerating area and the track belt is decelerated when the user is on the decelerating area.

14. The speed control apparatus as claimed in claim 13, further comprising:

a constant speed area set at the middle part on the track belt for maintaining the speed of the track belt at the time when the user reaches the constant speed area.

15. The speed control apparatus as claimed in claim 13, wherein the accelerating area and the decelerating area are divided into plural areas respectively, and the acceleration of the divided areas and the deceleration thereof are set differently with one another.

16. The speed control apparatus as claimed in claim 13, wherein the speed of the track belt is accelerated while the user moves forward although the user is not located at the accelerating area;

and wherein the speed of the track belt is decelerated while the user moves backward although the user is not located at the decelerating area.

17. The speed control apparatus as claimed in claim 13, wherein the speed of the track belt is firstly controlled by the user's movement, and then, the speed of the track belt is secondly controlled by the user's location.

18. The speed control apparatus as claimed in claim 13, wherein the values measured by the front load sensor and the rear load sensor are averaged for a predetermined unit time.

19. The speed control apparatus as claimed in claim 18, wherein in case that the difference between averaged measured values in accordance with the time becomes lower than the predetermined value;

and wherein the speed of the track belt is decelerated for an instance when the speed of the track belt is being accelerated; and the speed of the track belt is accelerated for an instance when the speed of the track belt is being decelerated.

20. The speed control apparatus as claimed in claim 18, wherein in case that the difference between averaged measured values in accordance with the time becomes lower than the predetermined value;

the acceleration degree of the track belt is lowered for an instance when the speed of the track belt is being accelerated; and the deceleration degree of the track belt is lowered for an instance when the speed of the track belt is being decelerated.