ROBOT CLEANER AND METHOD OF CONTROLLING TRAVELING THEREOF

Abstract

Disclosed herein are a robot cleaner that has an improved traveling performance, and a method of controlling traveling thereof. The robot cleaner allows driving wheels, which move the robot cleaner, and a brush unit, which sweeps dust on a floor, to be rotated in the same direction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Patent Ser. No. 61/186,529, filed on Jun. 12, 2009 in the USPTO and Korean Patent Application No. 2009-0079131, filed on Aug. 26, 2009 in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference.

BACKGROUND

1. Field

Embodiments relate to a robot cleaner that has an improved traveling performance, and a method of controlling traveling thereof.

2. Description of the Related Art

In general, a robot cleaner is an apparatus that sucks foreign substances, such as dust, from a floor while traveling on its own in a region to be cleaned without user manipulation, and thus performs a cleaning operation.

In such a robot cleaner, a pair of driving wheels is installed at both sides of the lower portion of a main body, and causes the main body to move forward or backward or to be rotated. The robot cleaner easily moves forward or backward on a hard floor, such as a wooden floor or an oilpaper floor. However, on a floor, such a carpet, resistance is high due to wool (or other fabric) and thus the robot cleaner cannot easily move forward or backward. Particularly, while the robot cleaner performs a cleaning operation by rotating a brush unit in one direction (forward moving direction), forward movement is easy due to the rotation of the brush unit in the forward moving direction. However, backward movement is difficult. In order to perform forward or backward movement, the driving wheels change a rotating direction thereof into the forward or backward direction, but the brush unit is uniformly rotated in the forward moving direction. Therefore, in order to perform backward movement, the robot cleaner requires the higher force, and if resistance is too great, the robot cleaner may not move backward.

SUMMARY

Accordingly, it is an aspect to provide a robot cleaner that has an improved traveling performance such that forward and backward movement is smoothly carried out on a floor having a high resistance, such as a carpet, and a method of controlling traveling thereof.

Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention.

The foregoing and/or other aspects are achieved by providing a robot cleaner including a main body, a plurality of driving wheels to move the main body, a brush unit rotated to sweep dust on a floor, and a control unit to control the brush unit to be rotated in a same direction as rotation of the driving wheels, when the main body travels backward.

The robot cleaner may further include a brush motor to rotate the brush unit in a regular or reverse direction, and driving motors to rotate the driving wheels in the regular or reverse direction, and the control unit may control the driving wheels and the brush unit to be rotated in the same direction.

The control unit may control forward and backward traveling of the main body by changing the rotating direction of the brush unit according to change of the rotating direction of the driving wheels.

The control unit may control the brush motor such that the brush motor is rotated at a relatively high speed in an initial stage when the rotating direction of the brush unit starts to be changed, and the rotating speed of the brush motor is relatively reduced when the rotating direction of the brush unit has been changed.

The foregoing and/or other aspects are achieved by providing a method of controlling traveling of a robot cleaner including a main body, a plurality of driving wheels to move the main body, a brush unit rotated to sweep dust on a floor, and a control unit to control the brush unit to be rotated in a same direction as rotation of the driving wheels according to a state of the floor, when the main body travels backward.

The robot cleaner may further include a floor surface sensor to sense the state of the floor, and the control unit may control the brush unit to be rotated in the same direction as rotation of the driving wheels, if the floor has a high traveling resistance.

The robot cleaner may further include driving sensors to sense movement of the driving wheels, and the control unit may control the brush unit to be rotated in the same direction as rotation of the driving wheels, if no movement of the driving wheels is sensed by the driving sensors.

The robot cleaner may further include driving motors to rotate the driving wheels in a regular or reverse direction, and a load sensor to sense a load applied to the driving motors, and the control unit may control the brush unit to be rotated in the same direction as rotation of the driving wheels, if the load is greater than a reference value.

The foregoing and/or other aspects are achieved by providing a method of controlling traveling of a robot cleaner, the method including detecting a rotating direction of driving wheels that move the robot cleaner, determining a rotating direction of a brush unit according to the rotating direction of the driving wheels, and moving the robot cleaner forward or backward including rotating the driving wheels and the brush unit in the same direction according to the determined rotating direction of the brush unit.

In the determination of the rotating direction of the brush unit, the rotating direction of the brush unit may be changed into a direction to allow the robot cleaner to smoothly travel forward when the driving wheels are rotated in a forward traveling direction of the robot cleaner.

In the determination of the rotating direction of the brush unit, the rotating direction of the brush unit may be changed into a direction to allow the robot cleaner to smoothly travel backward when the driving wheels are rotated in a backward traveling direction of the robot cleaner.

The method may further include sensing a state of a floor, and in the determination of the rotating direction of the brush unit, the rotating direction of the brush unit may be changed into the same direction as the rotating direction of the driving wheels, if the floor has a high traveling resistance.

The method may further include sensing movement of the driving wheels, and in the determination of the rotating direction of the brush unit, the rotating direction of the brush unit may be changed into the same direction as the rotating direction of the driving wheels, if no movement of the driving wheels is sensed.

The method may further include sensing a load applied to the driving wheels, and in the determination of the rotating direction of the brush unit, the rotating direction of the brush unit may be changed into the same direction as the rotating direction of the driving wheels, if the load is greater than a reference value.

The method may further include controlling the brush unit such that the brush unit is rotated at a relatively high speed in an initial stage when the rotating direction of the brush unit starts to be changed, and the rotating speed of the brush motor is relatively reduced when the rotating direction of the brush unit has been changed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a top perspective view of a robot cleaner in accordance with one embodiment;

FIG. 2 is a bottom perspective view of the robot cleaner in accordance with the embodiment;

FIG. 3 is a bottom view of the robot cleaner in accordance with the embodiment;

FIG. 4 is a perspective view of a brush unit in accordance with the embodiment;

FIG. 5 is a control block diagram of the robot cleaner in accordance with the embodiment;

FIG. 6 is a flow chart illustrating a method of controlling traveling of the robot cleaner in accordance with the embodiment;

FIG. 7 is a schematic view illustrating rotating directions of driving wheels and the brush unit when the robot cleaner in accordance with the embodiment travels forward; and

FIG. 8 is a schematic view illustrating rotating directions of the driving wheels and the brush unit when the robot cleaner in accordance with the embodiment travels backward.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

FIG. 1 is a top perspective view of a robot cleaner in accordance with one embodiment, FIG. 2 is a bottom perspective view of the robot cleaner in accordance with the embodiment, FIG. 3 is a bottom view of the robot cleaner in accordance with the embodiment, and FIG. 4 is a perspective view of a brush unit in accordance with the embodiment.

As shown in FIGS. 1 to 4, a robot cleaner 1 in accordance with this embodiment includes a main body 10 forming the external appearance of the robot cleaner 1, a driving device 20 installed at the lower portion of the main body 10 to move the robot cleaner 1, and brush devices 30 and 40 to sweep or disperse dust on a floor, on which the robot cleaner 1 travels, to clean the floor.

Further, a contact sensor and a proximity sensor together with the driving device 20 and the brush devices 30 and 40 may be installed on the main body 10. For example, a bumper 11 installed on the front portion of the main body 10 is used to sense an obstacle, such as a wall, and an infrared sensor (or an ultrasonic sensor) installed on the bottom of the main body 10 is used to sense an obstacle, such as a stair. The main body 10 may further include a display device 12 to inform a user of data regarding the state or operation of the robot cleaner 1.

The driving device 20 includes a pair of driving wheels 21 and 22 installed at both sides of the central portion of the main body 10 to adjust movement of the robot cleaner 1, and a caster wheel 23 installed at the front portion of the main body 10 such that the rotating angle of the caster wheel 23 is changed according to the state of the floor, on which the robot cleaner 1 moves. The caster wheel 23 is used to stabilize the posture of the robot cleaner 1 or to prevent the robot cleaner 1 from falling, and thus supports the robot cleaner 1. The caster wheel 23 is a wheel in the shape of a roller or a caster.

Both driving wheels 21 and 22 are respectively rotated in forward or backward directions according to instructions of a control unit, which will be described later, and thus cause the robot cleaner 1 to move forward or backward or to be rotated. For example, the robot cleaner 1 moves forward or backward by rotating the driving wheels 21 and 22 in the forward or backward direction. Further, the robot cleaner 1 is rotated in the left direction, as seen from the front part, by rotating the right driving wheel 22 in the forward direction while rotating the left driving wheel 21 in the backward direction, and the robot cleaner 1 is rotated in the right direction, as seen from the front part, by rotating the driving wheels 21 and 22 in the reverse directions, respectively.

The brush devices 30 and 40 include a main brush device 30 provided adjacent to a suction hole 14 formed through the bottom surface of the main body 10 and used to sweep and disperse dust on the floor to improve dust suction efficiency, and side brush devices 40 installed at both sides of the front portion of the bottom surface of the main body 10 to sweep the dust on the floor, on which the robot cleaner 1 travels, toward the suction hole 14.

The main brush device 30 includes a brush unit 31 formed in a drum shape, having a length corresponding to that of the suction hole 14, disposed horizontally adjacent to the suction hole 14 and rotated against the floor in a roller type to sweep or disperse dust accumulated on the floor, and a brush motor 32 to rotate the brush unit 31 in the forward or backward moving direction.

Further, the brush unit 31 includes a roller 33 and brushes 34. The roller 33 is made of a rigid body, rotatably connected to the main body 10, and is driven by the brush motor 32. An end cap 33a is installed at each of both side ends of the roller 33, and prevents foreign substances from moving to the brush motor 32. The brushes 34 are made of an elastic material and are implanted in the roller 33. The brushes 34 are driven together with the roller 33 during traveling of the robot cleaner 1, and agitate foreign substances, such as dust, accumulated on the floor.

The brush unit 31 may further include flaps 35 made of an elastic material. The plural flaps 35 are installed in the lengthwise direction of the roller 33, and are separated from each other by designated intervals. The flaps 35 serve to increase a diameter of the roller 33, on which foreign substances, such as hair, are wound, and minimizes frictional force of the foreign substances with the roller 33. That is, the flaps 35 prevent the foreign substances from being wound directly on the roller 33 and allow the foreign substance to be wound on the flaps 35, thereby minimizing frictional force of the foreign substances with the roller 33 and reducing energy required to remove the foreign substances from the roller 33.

The side brush devices 40 are respectively installed at both sides of the front portion of the bottom of the main body 10 at a designated interval, and each of the side brush devices 40 includes a side brush 41 rotated horizontally relative to the floor to sweep dust accumulated on the floor, on which the robot cleaner 1 travels, toward the suction hole 14.

The robot cleaner 1 in accordance with this embodiment further includes a dust collector to inhale foreign substances, such as dust, using suction force, and to store the inhaled foreign substances.

FIG. 5 is a control block diagram of the robot cleaner 1 in accordance with the embodiment. The robot cleaner 1 further includes a sensor unit 100 to sense various data regarding the robot cleaner 1 and a floor, on which the robot cleaner 1 travels, a control unit 110 to control rotating direction and speed of the brush unit 31 in connection with rotating directions (forward and backward directions) of the driving wheels 21 and 22 according to data sensed by the sending unit 100, and driving motors 120 to respectively drive the driving wheels 21 and 22 in the forward or backward moving direction according to driving instructions of the control unit 110.

The sensor unit 100 includes driving sensors 102 to sense movement of the driving wheels 21 and 22, a floor surface sensor 104 to sense a state of the floor, on which the robot cleaner 1 travels, and a load sensor 106 to sense loads applied to the driving motors 120.

The driving sensors 102 sense all data regarding the driving of the driving wheels 21 and 22, such as rotating directions and rotating speeds of the respective driving wheels 21 and 22 and torques transmitted to the respective driving wheels 21 and 22.

The floor surface sensor 104 senses whether or not the floor, on which the robot cleaner 1 travels, is a hard floor, such as a wooden floor or an oilpaper floor, or a cushiony floor having a high traveling resistance, such as a floor provided with a carpet, and transmits the sensed data to the control unit 110.

The load sensor 106 senses loads (a torque or a current value) applied to the driving motors 120, and transmits the sensed loads to the control unit 110.

Hereinafter, the operating process and effects of a method of controlling traveling of the above-described robot cleaner will be described

FIG. 6 is a flow chart illustrating the method of controlling traveling of the robot cleaner in accordance with the embodiment, FIG. 7 is a schematic view illustrating rotating directions of the driving wheels and the brush unit when the robot cleaner in accordance with the embodiment travels forward, and FIG. 8 is a schematic view illustrating rotating directions of the driving wheels and the brush unit when the robot cleaner in accordance with the embodiment travels backward.

In FIG. 6, when the robot cleaner 1 is operated, the control unit 110 judges whether or not cleaning is started (operation 200). When it is judged that cleaning is started, the control unit 110 transmits driving instructions to the driving motors 120 respectively installed at the driving wheels 21 and 22 to rotate the driving wheels 21 and 22 in the forward or backward direction (a regular or reverse direction), thereby allowing the robot cleaner 1 to travel on the floor while moving forward or backward or rotating (operation 202).

During traveling of the robot cleaner 1, the control unit 110 rotates the brush unit 31 to perform a cleaning operation. Here, in order to more smoothly carry out forward or backward traveling of the robot cleaner 1 according to the rotation of the brush unit 31, the driving sensors 102 detect a rotating direction of the driving wheels 21 and 22, and transmit the detected rotating direction of the driving wheels 21 and 22 to the control unit 110 (operation 204).

Thereafter, the control unit 110 determines a rotating direction of the brush unit 31 according to the rotating direction (the forward or backward direction) of the driving wheels 21 and 22, detected by the driving sensors 102 (operation 206).

For example, when the driving wheels 21 and 22 are rotated in the forward direction (the regular direction) to cause the robot cleaner 1 to travel forward, the control unit 110 determines the rotating direction of the brush unit 31 to be a direction to smoothly carry out the forward movement of the robot cleaner, i.e., the forward direction (the regular direction). When the driving wheels 21 and 22 are rotated in the backward direction to cause the robot cleaner 1 to travel backward, the control unit 110 determines the rotating direction of the brush unit 31 to be a direction to smoothly carry out the backward movement of the robot cleaner, i.e., the backward direction (the reverse direction). Thereafter, the control unit 110 transmits driving instructions to the brush motor 32.

Therefore, when the driving wheels 21 and 22 are rotated in the forward direction (the regular direction) of the robot cleaner 1, the brush motor 32 receives the driving instructions from the control unit 110 and is rotated in the forward direction (the regular direction) in the same way as the driving wheels 21 and 22, as shown in FIG. 7. When the driving wheels 21 and 22 are rotated in the backward direction (the reverse direction) of the robot cleaner 1, the brush motor 32 receives the driving instructions from the control unit 110 and is rotated in the backward direction (the reverse direction) in the same way as the driving wheels 21 and 22, as shown in FIG. 8. Thereby, the robot cleaner 1 performs a cleaning operation to suck foreign substances from the floor (operation 208).

As described above, when the rotating direction of the driving wheels 21 and 22 is changed into the regular or reverse direction to carry out the forward or backward movement of the robot cleaner 1, the brush unit 31 also receives the driving instructions from the control unit 110 and changes its rotating direction into the regular or reverse direction substantially simultaneously with the change of the rotating direction of the driving wheels 21 and 22, thereby causing the robot cleaner 1 to smoothly carry out the forward or backward movement. Particularly, the traveling performance of the robot cleaner 1 on a floor having a high resistance, such as a carpet, may be improved.

Thereafter, the control unit 110 determines whether or not cleaning is completed (operation 210), and when it is judged that cleaning is not completed, the process is fed back to operation 204 and then subsequent operations are repeated.

As a result of the determination of operation 210, when it is judged that cleaning is completed, the control unit 110 stops driving of the driving motors 120 and the brush motor 32, and thus stops the cleaning operation (operation 212).

FIG. 5 illustrates that the control unit 110 simultaneously transmits driving instructions to the driving motors 120 and the brush motor 32 and thus substantially simultaneously changes the rotating direction of the driving wheels 21 and 22 and the rotating direction of the brush unit 31. However, a case, in which the control unit 110 transmits driving instructions only to the driving motors 120 and thus changes the rotating direction of the driving wheels 21 and 22 such that the driving wheels 21 and 22 and the brush unit 31 are rotated in opposite directions, will be described below. Since the rotating direction of the brush unit 31 on a hard floor, such as a wooden floor or an oilpaper floor, does not matter, the change of the rotating direction of the brush unit 31 only on a floor having a high traveling resistance, such as a carpet, according to the rotating direction of the driving wheels 21 and 22 will be described. Here, the rotating direction of the brush unit 31 may be changed using data sensed by the sensing unit 110.

In one example, a case using the driving sensors 102 will be described. When the robot cleaner 1 moves backward so that that the driving wheels 21 and 22 and the brush unit 31 are rotated in opposite directions, and then meets a floor having a high traveling resistance or an obstacle, the driving wheels 21 and 22 may not be rotated due to the traveling resistance in spite of the driving instructions from the control unit 110. In this case, the driving sensors 102 sense movement of the driving wheels 21 and 22, and when the driving sensors 102 do sense no movement, the driving sensors 102 transmit the sensed result to the control unit 110. Then, the control unit 110 transmits driving instructions to the brush motor 32, and thus controls the brush unit 31 to be rotated in the same direction as the rotation of the driving motors 120.

In a further example, a case of using the floor surface sensor 104 will be described. When the robot cleaner 1 moves backward so that the driving wheels 21 and 22 and the brush unit 31 are rotated in opposite directions, and then meets a floor having a high traveling resistance, the floor surface sensor 104 senses that the floor has a high traveling resistance, and transmits the sensed result to the control unit 110. Then, the control unit 110 transmits driving instructions to the brush motor 32, and thus controls the brush unit 31 to be rotated in the same direction as the rotation of the driving motors 120.

In another example, a case using the load sensor 106 will be described. When the robot cleaner 1 moves backward so that the driving wheels 21 and 22 and the brush unit 31 are rotated in opposite directions, and then meets a floor having a high traveling resistance, a relatively large load is applied to the driving motors 102. When the load is greater than a designated reference value, the load sensor 106 senses that the load is greater than the designated reference value, and transmits the sensed result to the control unit 110. Then, the control unit 110 transmits driving instructions to the brush motor 32, and thus controls the brush unit 31 to be rotated in the same direction as the rotation of the driving motors 120.

Further, the control unit 110 transmits a relatively large torque to the brush motor 32 in an initial stage, when the rotating direction of the brush unit 31 starts to be changed, and transmits a relatively small torque to the brush motor 32, when change of the rotating direction of the brush unit 31 has been carried out. Thereby, during backward traveling of the robot cleaner 1, the rotating speed of the brush motor 32 is increased in the initial stage so as to withstand traveling resistance, and then is reduced when the backward traveling of the robot cleaner 1 starts to be carried out, thus exhibiting energy saving and noise reducing effects.

As is apparent from the above description, a robot cleaner in accordance with one embodiment allows driving wheels, which move the robot cleaner, and a brush unit, which sweeps dust on a floor, to be rotated in the same direction, and thus smoothly travels forward and backward even on a floor having a high traveling resistance, such as a carpet, thereby having an improved traveling performance.

Although a few embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit thereof, the scope of which is defined in the claims and their equivalents.

Claims

1. A robot cleaner, comprising:

a main body;

a plurality of driving wheels to move the main body;

a brush unit rotated to sweep dust on a floor; and

a control unit to control the brush unit to be rotated in a same direction as rotation of the driving wheels, when the main body travels backward.

2. The robot cleaner according to claim 1, further comprising:

a brush motor to rotate the brush unit in a forward or reverse direction; and

a plurality of driving motors to rotate the driving wheels in the forward or reverse direction,

wherein the control unit controls the driving wheels and the brush unit to be rotated in the same direction.

3. The robot cleaner according to claim 2, wherein the control unit controls forward and backward traveling of the main body by changing the rotating direction of the brush unit according to change of the rotating direction of the driving wheels.

4. The robot cleaner according to claim 3, wherein the control unit controls the brush motor such that the brush motor is rotated at a relatively high speed in an initial stage when the rotating direction of the brush unit starts to be changed, and the rotating speed of the brush motor is reduced when the rotating direction of the brush unit has been changed.

5. A robot cleaner comprising:

a main body;

a plurality of driving wheels to move the main body;

a brush unit rotated to sweep dust on a floor; and

a control unit to control the brush unit to be rotated in a same direction as rotation of the driving wheels according to a state of the floor, when the main body travels backward.

6. The robot cleaner according to claim 5, further comprising a floor surface sensor to sense the state of the floor, the state of the floor including a resistance, wherein the control unit controls the brush unit to be rotated in the same direction as the driving wheels, if the floor has a high resistance.

7. The robot cleaner according to claim 5, further comprising a plurality of driving sensors to sense movement of the driving wheels, wherein the control unit controls the brush unit to be rotated in the same direction as the driving wheels, if no movement of the driving wheels is sensed by the driving sensors.

8. The robot cleaner according to claim 5, further comprising driving motors to rotate the driving wheels in a forward or reverse direction, and a load sensor to sense a load applied to the driving motors, wherein the control unit controls the brush unit to be rotated in the same direction as the driving wheels, if the sensed load is greater than a reference value.

9. A method of controlling traveling of a robot cleaner, the method comprising:

detecting a rotating direction of driving wheels that move the robot cleaner;

determining a rotating direction of a brush unit according to the rotating direction of the driving wheels; and

moving the robot cleaner forward or backward comprising rotating the driving wheels and the brush unit in the same direction according to the determined rotating direction of the brush unit.

10. The method according to claim 9, wherein the determining the rotating direction of the brush unit comprises changing the rotating direction of the brush unit into a direction to allow the robot cleaner to smoothly travel forward when the driving wheels are rotated in the forward direction.

11. The method according to claim 9, wherein the determining of the rotating direction of the brush unit comprises changing the rotating direction of the brush unit into a direction to allow the robot cleaner to smoothly travel backward when the driving wheels are rotated in the backward direction.

12. The method according to claim 9, further comprising sensing a resistance of a floor, wherein, the determining of the rotating direction of the brush unit comprises changing the rotating direction of the brush unit into the same direction as the rotating direction of the driving wheels, if the floor has a high resistance.

13. The method according to claim 9, further comprising sensing movement of the driving wheels, wherein, the determining of the rotating direction of the brush unit comprises changing the rotating direction of the brush unit to the same direction as the rotating direction of the driving wheels, if no movement of the driving wheels is sensed.

14. The method according to claim 9, further comprising sensing a load applied to the driving wheels, wherein, the determining of the rotating direction of the brush unit comprises changing the rotating direction of the brush unit into the same direction as the rotating direction of the driving wheels, if the load is greater than a reference value.

15. The method according to claim 9, further comprising controlling the brush unit such that the brush unit is rotated at a relatively high speed in an initial stage when the rotating direction of the brush unit starts to be changed, and reducing the rotating speed of the brush motor when the rotating direction of the brush unit has been changed.