Intelligent Treadmill and Enhancements to Standard Treadmills

Info

Publication number: 20160213976
Type: Application
Filed: Jan 22, 2015
Publication Date: Jul 28, 2016
Inventors: Albert Ting-pat So (Bothell, WA), Jackson Ping-kuen Chack (Hong Kong), Kin Wa Yee (Hong Kong)
Application Number: 14/603,283

Abstract

An intelligent treadmill is described with modifications to existing treadmills, and associated methodology. The invention allows the conveyor belt automatically keeps track of and fixes the user's position dynamically with respect to a stationery reference point of the treadmill by adjusting its own speed free hands. Two position measurement techniques and their corresponding belt speed control algorithms are described. Other features of the invention allow users to perceive in real time how their surroundings would be changing by means of video, incline of platform, fan speed, sound and illumination as if they were in fact running in the natural environment. Real time positions of the runner and his partners on other treadmills with respect to a chosen track are displayed. The invention also utilizes a vectored controlled 2/3-phase AC induction motor or a BLDC motor to drive the conveyor belt for energy efficiency and fast response.

Description

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/966,247 filed Feb. 20, 2014, which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a device for walking or running while staying in the same place, commonly referred to a treadmill, enhancements and adaptations to existing treadmills, and associated methodology. Specifically, the treadmill aspect of the invention involves a modification to conventional drives found in domestic applications, a position sensing device, a speed controlling algorithm to dynamically fix the user or runner at the same position and a virtual environment to aid walking and running with Internet based social communication. In this document, the terms “user” and “runner” share the same meaning, i.e. the human body moving on the moving belt of the treadmill.

BACKGROUND OF THE INVENTION

Treadmills are popular exercise machines for running or walking in one place, usually indoors, including the home, school, fitness center, or even office. The basic treadmill provides an adjustable slanting platform on which a wide conveyor belt is running; the belt is driven by an electric motor through a sheave, usually Direct Current (DC) typed for home treadmills, with a rating from 1.5 to 4 horsepowers. Commercially graded treadmills used in gyms may employ Alternating Current (AC) motors. The conveyor belt moves in a way requiring the runner to walk or run at a speed matching that of the belt, which is usually adjustable but fixed. Here, “fixed” means that the speed is either constant or undergoes a continuous acceleration or deceleration over a short period of time until the speed becomes constant. This is the operation of common treadmills. The “fixed” rate at which the belt moves can be controlled by the runner on a control panel to a continuous rate from a slow walk or to a run, which is displayed on the control panel.

Most treadmills have at least the following standard functions: (1) controllable but constant speed of movement of the belt; (2) inclined setting allowing for consistent “uphill” training; (3) features to measure and display the heartbeat of the user; (4) preinstalled programs for simulating various exercise routines; (5) measurement of distance run by the runner, estimation of calories burned, and other performance measurements such as average speed; (6) audio and/or visual input or output allowing runners to listen to music from an audio device or audio-visual device, or both; (7) monitors allowing the user to view television, movies, or other visual materials; (8) a fan to blow air over the runner for cooling or to provide as if the runner were not standing still; and (9) a mechanism to stop the machine under emergency conditions when the runner moves to a rear position of the belt considered too unsafe for operation, such as a magnetic detector linked to the runner via a piece of string with a clip on the runner's cloth.

Having introduced the standard functions of conventional treadmills, we now turn to how conventional treadmills generally function and the problems with the standard design. One purpose of a treadmill is to allow for exercise via running or walking inside and in one place. One advantage of a treadmill over other exercise machines is the freedom of movement: it allows users walk or run as if they were not walking or running in place. In other words, treadmills allow users to walk or run in their natural strides, at the natural height in which they pick their feet up off the ground, move their hands freely as if they were not standing in place, and other movements which other exercise machines restrict. Even though this freedom of movement aspect is realistic in the sense runners would do the same if they were not standing in place, other features of how conventional treadmills shape the user experience are unrealistic.

One important unrealistic aspect of treadmills is due to the operation of treadmills in terms of the constant speed setting. Users adjust the speed of the conveyor belt manually, i.e., to change the speed users must consciously utilize an interface to adjust it. Once a new speed is set, the belt accelerates or decelerates gradually for a short period of time until the new speed of the belt is achieved. The constant speed operation imposes a strict pace on runners, perhaps giving an unnatural feel to running which can cause a runner to loose balance and feel discomfort. How the speed on standard treadmills is controlled is unrealistic because human beings do not naturally run under a constant speed; rather, people naturally move faster and slower slightly over time but usually the overall average speed, say in one hour, is almost constant. However, during normal operation, treadmills prevent the runner to adjust even small changes in speed, unless with the runner's conscious attention to key in a command on the control panel. In this regard, although speed control by the runner is relatively easy and straight forward, merely by requiring conscious effort to change speed even slightly does not always offer the psychological satisfaction that runners get from running outdoors or anywhere where speed control does not have to be a conscious effort.

A second important unrealistic aspect of treadmills is perhaps due to the problem treadmills attempted to solve in the first place: walking or running outdoor or indoor is unavailable. However, many treadmill users today use treadmills because of convenience—i.e., even when walking or running outside or somewhere inside is available. Nonetheless, the user experience of conventional treadmills is unrealistic compared with walking or running not-in-place because the runner is, by definition, not moving geographically and so the runner's surroundings are not changing. This psychological consideration may at first seem irrelevant because of the fact that the runner is indeed not moving geographically, but despite the obviousness of not moving geographically on a treadmill may take a toll on the runner's motivation and mental wellbeing at least compared to walking or running outdoor. One reason is that treadmill exercise does not allow runners to unconsciously compare their progress in the walk or run; instead, they must look to the treadmill's display of distance or time to check their progress based on these figures only. One could compare this to a runner who typically walks or runs a number of routes and thus knows the remaining distance or effort required to complete the desired exercise. The surrounding environment in such a walk or run allows the walker or runner to acquire mental estimation about the remaining distance, whereby the walker or runner can unconsciously decipher the remaining difference. This cannot happen on a treadmill. This psychological consideration is yet another unrealistic aspect of conventional treadmills. In a similar vein, standard treadmills are made for individual users—e.g., the belt is not wide enough, or designed, to allow two or more people walk or run on it together. Even if two runners walk or run side by side on adjacent treadmills, the feeling of companionship and support achieved from it is most likely less than by walking or running side by side in a natural environment as they know the pace of the other person. This perception of relative pace setting and comparison is what is lacking for treadmills, which perhaps can detract from one's motivation to exercise.

Having introduced the standard functions, general functioning, and a few unrealistic aspects of the standard treadmill design, we will now discuss the standard power drive and problems with it. Almost all existing home-use treadmills use DC motors with a rated voltage from 12 V to around 130 V. From a design standpoint, the speed and change in acceleration controls for DC motors are straightforward. Although DC motors are efficient at changing conveyor belt speeds, they are not energy efficient, not for swift acceleration or deceleration, and tend to require maintenance. Moreover, this technology is fading gradually in related machines. Current ratings for most standard home treadmill DC motors are below 4 (continuous) horsepowers (or about 3 kW) with a peak rotating speed of around 4,000 r.p.m. Generally, DC motors used for home treadmills are of the Permanent Magnet DC (PMDC) typed. The permanent magnets are installed at the stator. The rotor receives controlled DC current via commutators and brushes. The loss at the contacts between brushes and commutators is high and the optimal energy profile of DC motors cannot be controlled.

The present invention addresses the need to alleviate problems in both conventional home and industrial treadmills including: (a) the unrealistic constant speed aspect of standard treadmills due to requiring users to consciously utilize an interface to adjust even minor changes in speed; (b) the unrealistic user experience aspect of standard treadmills in that (i) because the user's surroundings are not changing (and, when users are exercising with one or more other people, not changing together in real time), users must consciously check their progress in the walk or run by viewing the display of distance or time instead of unconsciously knowing the percentage of the exercise completed or remaining; (ii) an unchanging user environment is not as mentally and emotionally stimulating as a changing environment; and (c) the relatively outdated and energy inefficient technology used to drive the conveyor belt for home treadmills.

SUMMARY OF THE INVENTION

The present invention involves a novel intelligent treadmill, adaptations to existing treadmills, and associated methodology. According to an aspect of the invention, the intelligent treadmill comprises the means of allowing the runner to automatically change the conveyer belt speed hands free, which can be done consciously or unconsciously. The hardware and algorithms involved are detailed in the invention. Upon changing the speed, the runner still keeps a more or less fixed position in space related to the indoor environment where the treadmill is placed. These means are in addition to the standard method of changing belt speed, that is, by the standard controllable manual speed settings or automatic exercise profiles. The automatic, hands free speed changing aspect of the present invention helps alleviate the unrealistic constant speed aspect of standard treadmills, which requires runners to consciously utilize an interface to adjust even minor changes in speed.

According to another aspect of the invention, the intelligent treadmill also comprises the means of allowing users to perceive in real time how their surroundings would be changing if they were in fact walking or running not-in-place. In addition, the intelligent treadmill aspect of the present invention comprises the means of simulating, communicating, and displaying the real time positions of two or more treadmill runners on different treadmills within said perceived surroundings. In other words, two or more treadmill users can perceive not only how they are progressing through the chosen surroundings; the present invention is also capable of including the position of other treadmill users within the surroundings in real time. These two former aspects of the present invention create a more realistic treadmill user experience for a runner to check his own or his running partners' progress by simply knowing the chosen surroundings.

According to another aspect of the invention, the intelligent treadmill also comprises the means of automatically varying the incline, fan speed, or other features on the treadmill to correspond to the conditions of the automated surroundings as well as for the comfort of the runner. By way of example only, imagine one course transitions from a hilly, wooded area to a flat beach. The intelligent treadmill may automatically adjust from an incline to zero incline based on the current position of the runner along the simulated trail, have the cooling fan at low speed in the wooded area turned to high speed near the beach (e.g., the wooded area has little moving air while there is a breeze next to the beach), and adjust the brightness of illumination of the treadmill from dim to bright (e.g., the tree cover in the wooded area blocks the sun while the sun is shining next to the beach). This is a kind of environmental background controls. According to another aspect of the invention, sound of bird singing can be played in the simulated wooded area, and sound of sea waves near the simulated beach.

According to an aspect of the invention, the present invention comprises a two or three phase AC induction motor, or a Brushless DC (BLDC) motor to drive the treadmill conveyor belt for better transient response as well as higher energy efficiency. The unique advantage of AC induction or BLDC motors in the context of the present invention is due to faster transient belt speed changes as compared with conventional treadmills, i.e., the present invention allows for automatic, hands free changing of the conveyor belt speed based on the sensing hardware and algorithms of this invention. At the same time, energy saving can be achieved. A previous invention involves the use of ultrasound distance measurement but the precision achieved was found not good enough for our application. An aspect of the invention makes use of laser technology for dynamic position sensing of the runner on the running belt. Another aspect of the invention makes use of pairs of poles, equipped with laser based obstacle sensors and installed by the two sides of the running belt, to detect the current position of the runner. One pair of poles installed at the rear of the treadmill helps to initiate an emergency stop when the runner falls back to such position. Due to this nature of the present invention, another aspect of the present invention comprises standard vectored control algorithms which utilize the relatively high transient torque of such AC or BLDC motors. In other words, the AC or BLDC motors are much more suitable for sudden acceleration and deceleration than the standard DC motors that have only one dimension of control, i.e. the DC current fed to the rotor. In this way, the response of AC or BLDC motors is even more immediate to fit the runner's performance. Furthermore, BLDC motors have a much higher torque-to-motor volume ratio, good for replacing traditional DC motors. In addition, AC and BLDC motors require less maintenance than standard DC motors used in conventional treadmills. Finally, the use of 3-phase AC or BLDC motors can improve energy efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood with regards to the following description, appended claims and drawings where:

FIG. 1 is a schematic representation of the structure of the intelligent treadmill of the present invention;

FIG. 2 is a schematic representation of the mechanism of distance measurement of the intelligent treadmill of the present invention;

FIG. 3 is a schematic representation of the monitor display of the intelligent treadmill of the present invention;

FIG. 4 is a schematic representation of first embodiment of measured distance by using laser reflector method of the intelligent treadmill of the present invention;

FIG. 5 is a schematic representation of second embodiment of measured distance by using three pair of poles and equipped with two sets of reflectors/receivers method of the intelligent treadmill of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1 of the drawings and in accordance with the principles of the invention, the intelligent treadmill comprises a touch screen monitor (1), transmitter/receiver (2), motor (3), electronic drive (4), control panel (5), reflector (6) and three pairs of poles (7), (8) and (9).

The said touch screen monitor (1) is equipped with a pair of loudspeakers and a dimmable lamp, displaying the video of the surrounding environment of an outdoor track, downloaded from the Internet and a simple map showing runner current position.

The said transmitter/receiver (2) is for distance measurement, which emits and receives a laser beam to help estimate the exact distance of the reflector of the runner away from it.

The said motor (3) is a vectored controlled 2/3-phase AC or BLDC motor that adjusts the speed of the conveyor belt to fix the runner at a more or less constant distance from the transmitter/receiver or at a dynamically stable and stationary position on the moving belt.

The said 2/3-phase AC or BLDC motor (3) is energized by an electronic drive (4) which gets power from a standard single phase supply.

The said control panel (5) is to control the speed of the treadmill and has additional control to adjust the speed of the conveyor belt to fix the user at a more or less constant distance from the transmitter/receiver (2) or at a dynamically stable and stationary position on the moving belt.

The said reflector (6) is worn on the waist belt of the runner, which is used to reflect the laser beam from the transmitter/receiver (2).

The said poles (7), (8) and (9) are installed on both sides of the platform of the said treadmill equipped with laser based transmitters, receivers and/or reflectors.

Every pole of a pair is situated on either side of the belt and the whole pair can move along the belt on rails underneath the platform on and below which the belt is moving. The initial positions of these poles are factory preset while the user can slightly adjust that of (8) and (9), but not (7). Without loss of generality, as an example, on pole (7) of one side, there are two transmitters/receivers, known as (7A) and (7B) ((A) being higher than (B) at about 300 mm and 150 mm respectively above the belt surface). On pole (7) of the other side, at the same levels, there are two reflectors, also known as (7A) and (7B). A laser beam is projected from transmitters (7A) and (7B) on one side to reflectors (7A) and (7B) on the other side and then received by receivers (7A) and (7B) on the same side of the transmitters respectively. This arrangement equally applies to pole-pairs (8) and (9). Such six sets of transmitters/reflectors/receivers can detect any blockage of the laser beam in the midst. According to an alternative aspect, only the transmitters are installed on the poles of one side while the receivers are installed on the poles of the other side. In this way, the reflector is omitted. Both designs serve the same purpose of detecting blockage of the laser beam in the midst.

Referring to FIG. 2, the drawing shows the mechanism of distance measurement. According to one aspect, a transmitter (2) continuously emits a laser beam which is reflected by a reflector (6) on the waist belt of the runner and picked up by a receiver (2). In this way, the accuracy of distance measurement is more precise because only the position of the abdomen of the runner is of concern. Even the posture of the runner changes, the abdomen remains more or less at the same position. Once the exact position of the reflector (6) is estimated, the position of the centre of gravity of the runner is calculated by adding half the thickness of the human body. The control algorithm as described in the following description controls the speed of the motor (3) to bring the runner at a more or less fixed position dynamically related to any stationary part of the treadmill. According to another aspect of position measurement, FIG. 2 also gives the side view of the three position measurement poles (7), (8) and (9), each with two transmitters/receivers and/or reflectors (A) and (B), depending on which side of the treadmill is shown in the figure.

Referring to FIG. 3, the drawing shows the normal display on the monitor (1) when the runner is treading along a preset track with or without partners, downloaded through the Internet, though other displays for user's setting are available. On the left, a simple map showing the trail is displayed with the starting/end point indicated. A dot, say red in color, indicates the instantaneous position of the runner while other dots of different colors, indicate the instantaneous positions of his partners as retrieved through the Internet. In this way, the runner knows his current position as well as that of his partners. It's like GPS navigation on the road map. Parameters including but not limited to the instantaneous speed of the runner, average speed of the whole group, percentage of track completed, and time remaining to finish the whole track are displayed under the map. On the right, a video of the surrounding environment of the trail, synchronous to the current speed and position of the runner, is displayed. If the runner runs faster, the video is played faster, and vice versa.

Referring to FIG. 4, the drawing shows how parameters are defined for belt speed and dynamic runner's position control when a reflector (6) on the waist belt worn by the runner is used to reflect the laser beam from the transmitter (2).

Referring to FIG. 5, the drawing shows how parameters are defined for belt speed and dynamic runner's position control when no waist belt is needed and position of runner is measured by the three pairs of poles (7), (8) and (9), each equipped with two sets of transmitters/receivers and/or reflectors (A) and (B).

Illustrative embodiments of the functioning of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. The novel treadmill, adaptations to existing treadmills, and associated methodology disclosed herein boast a variety of inventive features and components that warrant patent protection, both individually and in combination.

By way of examples only, a description of one embodiment of the automatic, hands free conveyor belt speed changer, the real time and interactive surroundings display, and associated methodology will be discussed. The automatic speed changer aspect of the invention addresses the unrealistic constant speed aspect of standard treadmills. For standard treadmills, users fix a belt speed which remains constant until the user modifies the speed manually. Only during the transition from one fixed belt speed to another fixed belt speed that there is short termed acceleration or deceleration. Obviously, the user must maintain a fairly constant velocity, i.e., if the user walks/runs too fast he will step off of the belt in the front of the machine onto the footrest covering the belt sheave/motor assembly underneath the control panel (5) or if he walks/runs too slow he will step off of the belt onto the floor. However, under standard treadmills, the fact that the run-able belt length is longer than one's stride allows the runner may momentarily slow or speed up his pace, which would move him toward or away from the front of the treadmill from his previous location, respectively. Then, the user can either revert back to his original speed and stay in the new location on the treadmill or momentarily speed up or slow down to reposition himself back to the original location, respectively. Regardless, current treadmills only allow users to speed up or slow down momentarily in that the belt speed is constant (with manual adjustment of the belt speed on rare occasions). An aspect of the present invention adjusts the belt speed automatically to fit the runner's desired change in velocity. For instance, if the runner begins to run faster, the belt will move faster, and vice versa. The ultimate target is to bring the dynamic position of the runner to the middle of the treadmill even when his speed keeps on changing.

According to an aspect of the invention, the treadmill includes one or more means of accurately measuring the distance between the runner and the front of the treadmill or ensuring the runner is dynamically trapped between two pairs of measurement poles. By way of example only, the intelligent treadmill uses a laser transmitter and receiver pair (2) (called the locator) which are installed right below the control panel (5). The height of the locator is adjustable to suit the level of the reflector (6). A previous invention (U.S. Pat. No. 6,733,423 B1 dated May 11, 2004) utilized an ultra-sound transmitter and receiver to measure the position of the runner on the running belt; that previous invention claimed that once the position was estimated, the speed of the belt could be adjusted. Upon implementing the methodology, three problems were found. First, ultra-sound waves hit the runner at different spots and therefore the reflected waves indicated a mixture of the position of different parts of the runner's body, thus significantly downgrading the accuracy. Second, the precision of ultra-sound distance measuring technology is well below the requirement which should be within a range of ±20 mm. Third, nothing on the speed control algorithm was mentioned in that previous invention. The locator measures the distance from itself to the runner's waist or other part of the runner's body equipped with a reflector (6), thus one single point of reflection. For instance, the user could wear a reflector on the middle front spot of the waist belt to reflect the laser beam. If accidentally the reflector (6) is out of sight from the laser team emitted by the transmitter (2), the belt speed remains unchanged.

According to an aspect of the invention, the intelligent treadmill utilizes this one or more measured distances of the runner to change the speed of the belt in order to fix the position of the runner dynamically at a desirable distance from a reference point on the treadmill, say at the middle of the belt. The dynamic position control algorithm related to this type of distance measurement is as follows, with reference to FIG. 4.

X_ois the desirable permanent position of the runner, say at the middle point along the moving belt, as measured from the laser transmitter/receiver (2). The running speed of the runner is s(t), a function of time t, with respect to the belt, not the indoor environment; the speed of the running belt is v(t), also a function of time, under continuous control by the system based on the dynamic position of the runner with respect to the indoor environment. The instantaneous horizontal distance between the centre of gravity of the runner and a stationery reference point right below the control panel (5) is given by x(t), also a function of time, which includes the distance, l, measured by the laser transmitter/receiver (2) and half the assumed thickness of the runner, about 0.15 m. Such added value can be keyed in by the runner.

The equation of dynamics is given by:

$\frac{\partial x}{\partial t} = (v - s)$

while the equation of the control algorithm is given by:

$\frac{\partial v}{\partial t} = - K_{P} (x - X_{o}) - K_{I} \int (x - X_{o}) \partial t \Rightarrow \frac{\partial^{2} x}{\partial t^{2}} = \frac{\partial v}{\partial t} - \frac{\partial s}{\partial t} = - K_{P} (x - X_{o}) - K_{I} \int (x - X_{o}) \partial t - \frac{\partial s}{\partial t}$

Here, K_pand K_Iare two factory pre-tuned positive real numbers which are the proportional gain and the integral gain respectively. Since s is arbitrarily varying due to the runner, this differential equation can only be solved once s is known with a goal to make ∥x−X_o∥²as small as possible. Having said that, the equation

$\frac{\partial v}{\partial t} = - K_{P} (x - X_{o}) - K_{I} \int (x - X_{o}) \partial t$

is good enough to facilitate the speed control action because x is measurable while all other parameters on the right handed side of the equation are known. An emergency stop is actuated when x(t) goes beyond a limit, indicating that the runner has been too close to the end of the moving belt.

Even a laser distance measuring system is used, the accuracy is still imprecise and sometimes non-deterministic because the posture of the runner keeps on changing on the belt. Also, it is easy that the reflector (6) cannot receive the laser team and is out of sight of the receiver (2). Hence, the measured x cannot accurately indicate the exact position of the centre of gravity of the runner.

In another aspect of the invention, the dynamic position of the runner is precisely kept within a confined spatial segment above the moving belt determined by two pairs of obstacle sensing poles (8) and (9) as shown in FIG. 5. Another pair of obstacle sensing pole (7) is for safety precaution as it indicates the end of the belt. The exact position of the poles is pre-designed but the runner can slightly adjust that of (8) and (9), but not (7). As shown in FIG. 1, obstacle sensing poles come in pairs, one on either side of the moving belt and they could be moved together along the belt on rails below the platform. On each pair of poles, one on either side of the belt, there are two laser transmitters/receivers on one side and two laser reflectors on the other side, (A) and (B) respectively. An alternative design does not involve the reflector, while transmitters (A) and (B) are on one side and receivers (A) and (B) are on the other side. Without loss of generality, a laser beam is projected from a transmitter (9A) on one side to a reflector (9A) on the other side, reflected back and received by a receiver on the transmitter side (9A). (9B), (8A), (8B), (7A) and (7B) work similarly. A flag which is binary, either “1” or “0”, is assigned by the control microprocessor to indicate whether any transmitter/reflector/receiver combination of a pole is blocked by an obstacle in the midst, e.g. the flag of (9B)=“1” when blocked or =“0” when clear. For this particular application, the obstacle that blocks is either the shoe, the foot or the leg of the runner because (A) is only less than 300 mm and (B) 150 mm above the moving belt. The dynamic position control algorithm for this setup is as follows, reference made to FIG. 5 again. Under this control algorithm, during operation, the runner is dynamically trapped in a spatial segment above the moving belt between pole pair (8) and pole pair (9), irrespective of his posture.

Pole pair (9) is at a horizontal distance X_f(f means front) from a reference point, say at the front rotating sheave of the belt right below the control panel (5). Pole pair (8) is at distance X_r(r means rear) from the same reference point and Pole pair (7) is at a distance X_e(e means end) from the same reference point. The desirable dynamic position of the runner is still at X_ofrom the reference point as shown in FIG. 4, which is in the middle between X_fand X_r. X_fis factory pre-adjusted to about X_o−0.3 m and X_rto X_o+0.3 m, bearing in mid that the runner can slightly adjust that. However, X_emarks the end of the belt, which cannot be adjusted. Again, v(t) is the instantaneous speed of the moving belt under control and it obeys the following control algorithms in Table 1. The binary flags are checked within a time period of one complete control cycle taken by the belt to travel twice a distance of (X_r−X_f), thus dependent on the speed of running belt, v. One complete control cycle is the average total time spent by two strides completed by the left and right feet of the runner, equal to one cycle of walking or running on the belt. For example, if the factory preset positions of (8) and (9) are unchanged, they are about 0.6 m apart, and the time period of one control cycle is then equal to 1.44 second if the instantaneous belt speed is 3 km/hr. Once a flag is equal to “1” at anytime within the control cycle, it is assigned a value of “1” for the whole control cycle. And the control action is determined and executed at the end of every control cycle, after which all flags are automatically reset to “0”.

In Table 1, K_Ibears the same meaning as the factory pre-tuned positive parameter which is the integral gain; C₁is the acceleration of the belt (positive or negative) at the beginning of the current control cycle; C₂is the moving belt speed of the current control cycle.

TABLE 1 Action at the Equivalent beginning of Action for the Flags of 7: A Flags of 8: A Flags of 9: A next control next control and B and B and B cycle cycle All “0” All “0” Either one “1”

\frac{dv}{dt} = K_{I} \int dt

\frac{dv}{dt} = K_{I} t + C_{1}

All “0” Either one “1” Either one “1”

\frac{dv}{dt} = 0

v = C₂ All “0” All “0” All “0”

\frac{dv}{dt} = 0

v = C₂ All “0” Either one “1” All “0”

\frac{dv}{dt} = - K_{I} \int dt

\frac{dv}{dt} = - K_{I} t + C_{1}

Either one “1” Whatever Whatever v = 0 Maximum deceleration to a safe stop

One feature of the present invention allows for and utilizes the fact that the runner basically maintains a more or less fixed spatial position relative to the treadmill when the transmitter/receiver (2) is utilized. According to an aspect of the invention, the intelligent treadmill can learn this desired operating position, by way of example only, via the controller during the parameter setting stage when the runner is running on the moving belt under a constant speed. The controller then knows where the runner feels comfortable on the moving belt. Or the user can slightly and manually adjust the positions of the two pole pairs (8) and (9) to change the exact spatial segment to which the runner's position is dynamically confined. To expand on one example above, when the treadmill is turned on, it runs at a constant speed and it takes, say, half a minute for the treadmill controller to learn the comfortable position of the runner when obstacle sensing pole pairs are not utilized. Then, the treadmill will go to the automatic speed or dynamic position control mode where the position of the runner is dynamically fixed at a distance from the transmitter (2) and an “automatic speed control” indicator is lit up on the control panel (5). If the obstacle sensing pole pairs are active, no such tuning is necessary.

According to an aspect of the invention, the treadmill includes the means of automatically stopping the conveyor belt in a short period of time, whether it is for emergency or other reasons. By way of example only, it is contemplated that the automatic stopping means utilize the activation of any one of two obstacle sensing devices on pole pair (7), in combination to or separate from other means, thus fully replacing standard function (9) of a conventional treadmill as mentioned before.

In this invention, motors (3) for home treadmills will either be 2/3-phase AC induction motors or BLDC (brushless DC) motors, with a rated capacity up to 3 kW though in real operation, they are usually not fully loaded with the help of vector controlled PWM (pulsed width modulation) voltage pulses while a high efficiency can be maintained. Vector controlled PWM voltage and current control can ensure and improved transient response of speed control and energy efficiency. Electrically, there is no difference between a 2-phase AC motor and a 3-phase AC motor when either one is driven by a PWM based Variable Voltage and Variable Frequency drive.

According to an aspect of the invention, the intelligent treadmill has the means of allowing the user to connect to, download, and upload data between the treadmill and other computer devices, data storage devices, the Internet (either wireless or wired), or other ways of transferring and receiving data. By way of example only, one scenario of the functioning of the treadmill will be discussed. It is appreciated that this is only one example of an embodiment of the present invention, which only includes a number of applications of the features of the present invention. The treadmill includes the provision of a “mobile app” on a standard smart phone. Video clips of popular trails or tracks of the natural environment with beautiful scenery are provided and downloaded onto the smart phone which is connected to the Internet through Wi-Fi or data through cell phone carriers and to the control panel (5) through Bluetooth or Wi-Fi. When the runner is running on the belt, the surrounding environment keeps on changing, synchronous to his own pace, controlled to fit by the belt speed, and is displayed on the monitor (1) as if he were running on the real natural environmental track outdoor. This is like the on-site navigation service provided on the Google map. By the side of the video, the track is shown on a small map while the current position of the runner is highlighted by a particular symbol, say a red dot. Under the map, information including but not limited to information such as current average speed of runner, average speed of the group, percentage of track completed by the runner and estimated time to finish the whole track under the current speed etc. are displayed. In this way, the runner can know where he is at present and see the natural environment at this particular position of the real track. If he runs faster or slower, the video and the symbol on the map will match in synchronism. The algorithm is described as follows.

The video of treading the track of the natural environment is filmed by a mobile camera of the service provider under a constant speed of movement, V_f, say 0.5 m/s, using a constant frame rate, fr, say 25 frames per second, as examples, but there could be other choices of V_fand fr. The position, p, a real number in meters, of the runner on the simulated track at any instant, t, as experienced by the runner is estimated from the starting point of the track when t=0 second, i.e. the time when the runner starts to tread on the treadmill. If the instantaneous treading speed of the runner on the treadmill, s(t) almost equal to v(t) based on the control algorithms of this invention, is known and recorded, p(t) is estimated to be:

$p (t) = \int_{0}^{t} v \partial t .$

Since the video was filmed by a mobile camera under constant speed, V_f, each frame on the video corresponds to a particular position on the track because advancing one frame on the video implies advancing the track by V_f/fr meters. In this case, p(t) actually relates to (p*fr)/V_f, rounded to the nearest integer, which is the current frame number on the video. Such frame number is also equivalent to the video time code of a linear time code format. The controller of the treadmill keeps on tracking v(t) and thus p(t) and hence the number of frames elapsed since the beginning when t=0 s. If L is the total length of the whole track, current percentage finished by the runner as shown below the map on the monitor (1) is calculated by (p/L)*100%. It is this value p(t) that is used by the control system of the treadmill as a tag to advance the video and change the environmental background, such as slope of treadmill platform, music, speed of circulating fan, and illumination etc., synchronously as experienced by the runner with reference to the following table, Table 2, which is downloaded from the “mobile app” for a particular track. Table 2 includes those parameters for environmental background controls.

TABLE 2 p % slope or tilting frame number music level of speed of in of angle of tread- or time code or illumi- circulating m L mill platform on video sound nation fan (%) file

Basically, the playing speed of the video is synchronous with v(t), given by: [v(t)/V_f]*[normal playing speed equal to the filming speed], while the exact instantaneous scene of the video is synchronous with p(t).

Since the whole system is Internet connected, according to an aspect of this invention, the runner can invite partner(s) to run or jog on the same track as involved in one exercise. All involved could see similar video but the exact scene depends on the instantaneous position of each individual runner along the agreed track. In other words, each runner involved in the exercise has his own p(t). And all of them could see their exact positions on the map by the side with different symbols, say dots of different colors as examples. This is because different p(t) of different runners are exchanged through the Internet so that the controller of every treadmill knows the exact p(t) of every other runner involved in the exercise, in addition to the local runner. The instantaneous position p(t) of each individual runner is calculated by the speed of belt synchronous to the varying running speed of each individual runner while the environmental background control is synchronous with each individual runner. The only parameters that are exchanged between the treadmill controllers of different runners are the various p(t) of different runners. In this way, those running slower could speed up or slow down to catch up with other partners and vice versa.

At the same time, they can talk to one another through the smart phones or the Internet and a background sound and music of that environment is played to improve the fidelity based on the data file as shown in Table 2 downloaded from the “mobile app”. Runners virtually at the same spot on the simulated track enjoy the same background, including but not limited to tilting angle of the belt, sound or music file, level of illumination and the speed of the circulating fan. But runners who have finished different percentage of the track experience different video and background. Sound from the loudspeakers of the monitor (1) and speed of the circulating fan on the control panel (5) are adjusted accordingly to reflect the environment shown by the video. Tracks are updated from time to time by the service provider so that the scenery of different seasons of the same track is available for downloading to enhance the treading experience of the runner and his partners. The tilting angle of the platform and the running belt of the treadmill is continuously adjusted according to the instantaneous position of the track which simulates the real natural environment. In this way, the runner has an up-climbing experience when the track is leading to a hill. Subject to the existing limitation of treadmill design, the tilting angle can at most be lowered to zero degree, i.e. horizontal. In the future, new treadmill design may include a down tilting angle to fit the simulated track.

Although the present invention has been described in considerable detail in reference to preferred versions, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.

Claims

1. An intelligent treadmill allowing the conveyor belt automatically keeps track of and fixes the runner position dynamically with respect to a stationary reference point of the treadmill by adjusting its own speed free hands based on speed varying algorithms, the said intelligent treadmill comprising: a touch screen monitor, transmitter/receiver, motor, electronic drive, control panel, reflector and three pairs of poles,

the said touch screen monitor equipped with a pair of loudspeakers and lamp, displaying the video of the surrounding environment of an outdoor track, downloaded from the Internet and a simple map showing current position of runner,

the said receiver for distance measurement emitting and receiving a laser beam to help estimate the exact distance of the reflector on the said runner away from it,

the said motor which is a vectored controlled pulse width modulation based two or three phase alternating current or brushless direct current motor to adjust the speed of the conveyor belt to fix the said runner at a more or less constant distance from the transmitter/receiver or at a dynamically stable and stationary position on the moving belt,

the said motor which is energized by an electronic drive which gets power from a standard single phase supply,

the said control panel which controls the speed of the treadmill and has additional control to adjust the speed of the conveyor belt to fix the said runner at a more or less constant distance from the transmitter/receiver or at a dynamically stable and stationary position on the belt,

the said reflector worn on the waist belt of the said runner for reflecting the laser beam from the said transmitter/receiver,

the said three pairs of poles installed on both sides of the platform of the said treadmill equipped with laser based transmitters, receivers and reflectors.

2. The intelligent treadmill of claim 1 wherein said means for measuring instantaneous position of the said runner of the said treadmill comprise a laser based transmitter and receiver installed at an appropriate position of the said treadmill, and a reflector worn on the body of the said runner.

3. An intelligent treadmill of claim 1 wherein said means for measuring instantaneous position of the said runner comprise several pairs of poles installed on both sides of the said platform of the said treadmill at appropriate positions, equipped with laser based transmitters, receivers and reflectors for detecting the existence of any obstacle between two corresponding said poles.

4. An intelligent treadmill of claim 2 wherein said a speed varying algorithm of the conveyor belt of the said treadmill based on the said position of said runner measured of claim 2 is according to a set of differential equations with tuned gains, KI and KP, for automatically and dynamically fixing the said position of said runner at a desirable position on the moving belt with reference to a stationary point of the said treadmill.

5. An intelligent treadmill of claim 3 wherein said a speed varying algorithm of the conveyor belt of the said treadmill based on the said position of said runner measured of claim 3 is according to a set of differential equations with tuned gains, KI, C1 and C2, for automatically and dynamically fixing the said position of said runner at a desirable position on the moving belt with reference to a stationary point of the said treadmill.

6. An intelligent treadmill of claim 3 and claim 4 wherein an emergency stopping procedure stops the moving belt when either the said position of claim 3 or the said position of claim 4 exceeds a safety limit.

7. An intelligent treadmill of claim 1 wherein said means for keeping track of the instantaneous position of the said runner with respect to the said outdoor track for synchronization of the video display and environmental background controls, means for continuously updating the said position of the said runner along the said track based on the said speed of the conveyor belt for displaying the corresponding scene of the surrounding environment of the said track, the said position of the runner on a map of the said track and parameters on the said monitor, and means for providing environmental background control at the local said treadmill including incline of said platform, music and sound, speed of circulating fan on a control panel of the said treadmill, and the level of illumination, are provided.

8. An intelligent treadmill of claim 1 wherein said means for intercommunicating the instantaneous positions of said runners on different said treadmills using the same outdoor track for displaying the updated positions of all said runners on the said monitors, allowing a group of said runners running on their corresponding said treadmills, exchanging instantaneous positions of said runners, and displaying positions of all said runners of the said group on the map of common said outdoor track on all said monitors.