Abstract:
Provided is a robot cleaner. In an embodiment, the robot cleaner for avoiding obstacles and sucking foreign materials using a plurality of sensors and a suction motor is characterized in that a drive suppression unit for detecting obstacles having a corresponding height is integrated with a base for forming a lower portion of a main body in order to not climb obstacles of a constant height during a driving period of the robot cleaner. The present disclosure according to the embodiment improves drive stability of the robot cleaner by sensing a threshold in erroneous state of the sensor for sensing the threshold.

Description:
This application is a National Stage Entry of International Application No. PCT/KR2009/003563, filed Jun. 30, 2009 which is incorporated herein by reference for all purposes. 
     BACKGROUND 
     The present disclosure relates a robot cleaner. 
     In general, robot cleaners are cleaning apparatuses which absorb dusts and foreign substances existing on a bottom surface together with air to remove the dusts and foreign substances while driving an area to be cleaned by oneself without the need for continuous manipulation. 
     For this, such a robot cleaner includes a plurality of sensors such as a sensor for detecting obstacles and a sensor for detecting a bottom surface, a threshold, a cliff, etc. 
     Among this, the sensor for detecting the bottom surface, threshold, and cliff may be disposed on a base constituting a lower portion of the robot cleaner to transmit light or infrared light toward a lower side. Then, the sensor may classify the bottom, threshold, and cliff according to a received value using received information to perform avoidance driving depending on the classified results. 
     However, in the robot cleaner according to the related art, when the sensors for detecting the bottom, the threshold, or the cliff are malfunctioned, the robot cleaner may be damaged. 
     That is, when the threshold is not detected due to the malfunction of the sensors, the robot cleaner may get out of a required cleaning area. Also, when the cliff is not detected, the robot cleaner may fall down and thus be damaged. 
     SUMMARY 
     Embodiments provide a robot cleaner which detects a threshold or obstacle having a drive suppression height due to a lower configuration of a base. 
     Embodiments also provide a robot cleaner including a caster for reducing an impact occurring when the robot cleaner passes through a threshold or obstacle having a drive allowance height. 
     In one embodiment, a robot cleaner which sucks foreign substances on an area to be cleaned while avoiding an obstacle using a plurality of sensors and a suction motor includes: a base defining a lower portion of a main body; and a drive suppression unit integrated with the base, the drive suppression unit interfering with an obstacle having a predetermined height to prevent the robot cleaner from passing over the obstacle having the predetermined height. 
     The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a robot cleaner according to an embodiment. 
         FIG. 2  is a partial bottom view of a robot cleaner according to an embodiment. 
         FIG. 3  is a sectional view taken along line A-A of  FIG. 2 . 
         FIGS. 4 and 5  are schematic views illustrating a caster of a robot cleaner according to an embodiment. 
         FIG. 6  is a view illustrating a threshold avoidance driving state of a robot cleaner according to an embodiment. 
         FIG. 7  is a view illustrating a driving state passing over a threshold in a robot cleaner according to an embodiment. 
         FIGS. 8 and 9  are schematic views illustrating an operation structure of the caster in the driving state of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, that alternate embodiments included in other retrogressive inventions or falling within the spirit and scope of the present disclosure will fully convey the concept of the invention to those skilled in the art. 
       FIG. 1  is a side view of a robot cleaner according to an embodiment. 
     Referring to  FIG. 1 , a robot cleaner  1  according to the current embodiment includes a base  100  defining a lower portion of a main body and a cover  200  covering an upper side of the base  100  to define an upper portion of the main body. Here, an outer appearance of the robot cleaner  1  may be defined by the base  100  and the cover  200 . A suction motor for sucking dusts and a plurality of electric components may be disposed within an inner space defined by coupling the base  100  to the cover  200 . 
     A sensor mounting unit  300  is disposed on the base  200 . Here, a plurality of sensors arranged along an edge of the base  200  with a predetermined distance to detect and avoid obstacles and walls so that the robot cleaner  1  drives an area to be cleaned are disposed on the sensor mounting unit  300 . 
     Also, the base  100  includes a drive wheel  500  and caster  600  for moving the robot cleaner  1  and an agitator (see reference numeral  160  of  FIG. 2 ) and side brush  400  for scattering foreign substances on the area to be cleaned. 
     For detailed description,  FIG. 2  illustrates a partial bottom view of the robot cleaner according to an embodiment. 
     Referring to  FIG. 2 , the agitator  160  is rotatably disposed on a dust suction unit (not shown) disposed on a bottom surface of the base  100 . The side brush  400  may be disposed at a side of the agitator  160 . 
     The drive wheel  500  for moving the robot cleaner  1  is disposed at a rear side of the side brush  400 . The caster  600  for assisting the movement of the robot cleaner  1  is disposed at a front side of the agitator  160 . 
     A drive suppression unit  120  for suppressing the driving of the robot cleaner  1  is disposed on the base  100 . The drive suppression unit  120  may structurally classify the obstacles into climbable obstacles and unclimbable obstacles according to heights of the obstacles. 
     For this, the drive suppression unit  120  includes a sensor receiving groove  124  in which a portion of the base  100  is recessed and a hook  122  relatively protruding with respect to the recessed sensor receiving groove  124  to interfere with a portion of the obstacles during the driving. 
       FIG. 3  is a sectional view taken along line A-A of  FIG. 2 . 
     Referring to  FIG. 3 , a front portion of the base  100  may have a thickness gradually increasing from a front side to a rear side. 
     The sensor receiving groove  124  may provide a space for mounting a detection sensor that is recessed in an arc shape at a front side of the drive wheel  500  along an edge of the base  100  to detect a threshold or cliff. 
     Thus, the sensor receiving groove  124  may have a deep depth at a rear side when compared to a front side with respect to the bottom surface of the base  100 . Also, the sensor receiving groove  124  may have a width corresponding to a size of the detection sensor  126 . 
     Also, a plurality of sensor mounting holes (not shown) may be disposed spaced a predetermined distance from each other on a bottom surface of the sensor receiving groove  124 . The detection sensor  126  may be fitted into the sensor mounting holes. 
     A semiconductor photo sensor for detecting the cliff and threshold through a resistance variable according to the amount of light may be used as the detection sensor  126 . In the current embodiment, a CdS sensor is used as the detection sensor  126 . 
     The sensor receiving groove  124  may be recessed, and also the rear side of the base  100  may further protrude than the front side of the base  100  due to the configuration of the base  100  to form the hook  122 . Like the sensor receiving groove  124 , the hook  122  may be disposed on an edge of a front side of the base  100 . 
     Thus, the protruding height of the hook  122  may be determined when the base  100  is formed. Also, the protruding range of the hook  122  may be determined in consideration of a range in which the caster  600  can pass over the obstacles. 
     That is, the hook  122  may prevent the robot cleaner  1  from passing obstacles, over which should not pass, such as a threshold toward a front door or a bathroom threshold in the obstacles over through the robot cleaner  1  can pass. The hook  122  may protrude so that an end of the hook  122  is disposed at a position higher than that of an upper end of a wheel  610  of the caster  600  and lower than that of a center of the wheel  610 . 
     Also, the hook  122  may be disposed in a direction perpendicular to the mounting position of the detection sensor  126  to define an inflow path of light detected by the detection sensor  126 . 
     Thus, when the hook  122  contacts the obstacle, since light incident from a rear side of the hook  122  is blocked, the amount of light incident into the detection sensor may be significantly reduced to more improve the obstacle detection performance of the detection sensor  126 . 
     When the robot cleaner  1  reaches the cliff, light may be blocked by the hook  122  due to a small light incident angle. Thus, light incident into a rear side of the hook  122 , which is not incident into the detection sensor  126 , may be incident into the detection sensor  126  because a gap between the bottom surface and the hook  122  becomes large. 
     That is, when the gap between the hook  122  and the bottom surface is large, the large amount of light having a relatively large light incident angle may be incident into the detection sensor  126 . Thus, a variation of the amount of light may be increased to improve the cliff detection performance of the detection sensor  126 . 
     A caster mounting unit  140  recessed inward may be disposed on the base  100  to mount the caster  600  for assisting the driving of the robot cleaner  1 . 
     Hereinafter, a structure and an operation of the door basket  600  will be described in detail with reference to the accompanying drawings. 
       FIGS. 4 and 5  are schematic views illustrating the caster of the robot cleaner according to an embodiment. 
     As shown in  FIGS. 4 and 5 , the caster  600  of the robot cleaner  1  according to an embodiment includes a main shaft  620  for rotating the wheel  610  at an angle of about 360°, a variable frame  680  rotatably connected to the main frame  620 , and an elastic member  670  for elastically supporting the variable frame  680 . 
     In detail, the main shaft  620  is rotatably fixed to the caster mounting unit  140  disposed on the base  100 . 
     The main shaft  620  may be disposed on a central portion of the caster mounting unit  140  so that an upper end thereof passes through the central portion of the caster mounting unit  140 . An end of the main shaft  620  exposed to the outside of the caster mounting unit  140  may be fixed using a separate fixing pin to allow the main shaft  620  to be rotated separately with respect to the caster mounting unit  140 . 
     To smoothly rotate the main shaft  620 , a bush  640  for receiving the main shaft  620  and a bearing  650  disposed within the bush  640  may be further disposed inside the caster mounting unit  140 . Accordingly, the caster  600  may be smoothly rotated at an angle of about 360°. 
     Also, the variable frame  680  may be fixed to the main shaft  620  through a shaft fixing pin  630  so that the wheel  610  having a side for performing a rolling motion while contacting the bottom or obstacles and rotatably fixed to the main shaft  620  is connected to the main shaft  620 . 
     The shaft fixing pin  630  may pass through a center of the variable frame  680  and the main shaft  620  and be fixed to the main shaft  620  to define a rotation center of the variable frame  680 . 
     A member support unit  622  extending downward from the variable frame  680  may be disposed on an end of the main shaft  620 . 
     The elastic member  670  for elastically supporting the variable frame  680  may be disposed between the other side of the variable frame  680  which is not connected to the wheel  610  and the member support unit  622  disposed under the variable frame  680  extending from the main shaft  620 . 
     The elastic member  670  may have a size enough to contact the variable frame  680  and the member support unit  622 . The elastic member  670  may be formed of an elasticible material. In the current embodiment, a coil spring may be used as the elastic member  670 . 
     Also, the elastic member  670  may include a torsion spring. That is, the elastic member  670  may be connected to the shaft fixing pin  630  connecting the main shaft  620  to the variable frame  680  to perform the same function. 
     As described above, when the elastic member  670  is provided, a restoring force of the elastic member  670  may be applied to the variable frame  680  so that the variable frame  680  is inclined in one direction. 
     Thus, a support frame  660  for horizontally maintaining the variable frame  680  in a state the variable frame  680  does not contact the obstacles may be disposed on the main shaft  620 . 
     The support frame  660  may be fixed to the main shaft  620  at a position spaced a predetermined height upward from the variable frame  680  so that the variable frame  680  secures a rotatable space thereof. Also, an end of the support frame  660  may be bent so that it is disposed under an end of the horizontally variable frame  680  in a direction opposite to that in which the restoring force of the elastic member  670  is applied. 
     Thus, even though the restoring force of the elastic member  670  is continuously applied to the variable frame  680 , the movement of the variable frame  680  may be suppressed by the support frame  660  in the direction in which the restoring force is applied. Thus, the variable frame  680  may be maintained in the horizontal state. 
       FIG. 6  is a view illustrating a threshold avoidance driving state of the robot cleaner according to an embodiment. 
       FIG. 6A  illustrates a state in which the robot cleaner  1  reaches a threshold T and then is stopped during the cleaning. When the robot cleaner  1  driven toward the threshold T contacts the threshold T during the cleaning, the hook  122  may interfere with the threshold T to stop the movement of the robot cleaner  1 . 
     In the above-described state, the amount of light incident into the detection sensor  126  may be reduced by the hook  122  and the threshold T. Thus, the robot cleaner  1  recognizes the threshold T as an obstacle that should not pass over. 
     As described above, the threshold T having the predetermined height may be disposed between the front door and a living room or the living room and the bathroom. A space over the threshold T may be excepted from the area to be cleaned using the robot cleaner  1 . 
     Thus, as shown in  FIG. 6B , the robot cleaner  1  may be moved in a direction away from the threshold T. When the robot cleaner  1  is spaced a predetermine distance from the threshold T, the robot cleaner  1  may be changed in a moving direction to avoid the threshold T, and then continuously drive the area to be cleaned. 
     Also, when the robot cleaner  1  approach the threshold T at a low speed, the robot cleaner  1  may detect first the threshold T through the amount of light incident into the detection sensor  126  before the hook  122  interferes with the threshold T. Thus, before the hook  122  collides with the threshold T, the robot cleaner  1  avoids the threshold T. 
       FIG. 7  is a view illustrating a threshold avoidance driving state of the robot cleaner according to an embodiment. 
       FIG. 7A  illustrates a state in which the robot cleaner  1  is driven toward a threshold T or obstacle having a relatively low height during the cleaning. Here, since the threshold T has a height less than the protruding length of the hook  122 , the robot cleaner  1  may pass over the threshold T. 
     The threshold T having the above-described height may be disposed between a room and a room or a riving room and a room. Thus, the threshold T may be included in the area to be cleaned. 
     Thus, as shown in  FIG. 7B , the robot cleaner  1  may pass over the threshold T having the above-described height. Here, the caster  600  may be varied in height to reduce an impact applied to the robot cleaner  1 . 
     In detail,  FIGS. 8 and 9  are schematic views illustrating an operation structure of the caster in the driving state of  FIG. 7 . 
     As described above, in the robot cleaner  1  driven toward the threshold T having a relatively low height, the hook  122  does not interfere with the threshold T. 
     Thus, after the wheel  610  contacts the threshold T, the robot cleaner  1  may be continuously driven to pass over the threshold T. 
     Here, the wheel  610  may be lifted upward, and thus a side of the variable frame  680  connected to the wheel  610  may be rotated upward and the other side may be rotated downward to compress the elastic member  670 , thereby realizing the state as shown in  FIG. 9 . 
     When the robot cleaner  1  is continuously driven after the above-described state, the caster  600  and the drive wheel  500  may pass over the threshold T to contact the bottom surface. 
     Here, the caster  600  compressed by the elastic member  670  may be released by the movement of the wheel  610 . Thus, as shown in  FIG. 8 , the variable frame  680  may be returned to its initial position by the restoring force. 
     In the restoring process, the elastic member  670  may be vibrated several times until the variable frame  680  is returned to the initial position thereof to stabilize the position of the variable frame  680 . Then, the stabilized variable frame  680  may be stopped by the support frame  660  at the initial position. 
     Therefore, since the impact applied to the robot cleaner  1  when the robot cleaner  1  pass over the obstacles is reduced, the drive stability of the robot cleaner  1  may be improved. 
     In the robot cleaner according to the embodiments, the driving operation of the robot cleaner may be suppressed by the drive suppression unit including the sensor receiving groove recessed in the base and the hook protruding from the base. 
     That is, due to the concern of damage of the robot cleaner, the drive suppression unit may classify the obstacles into the climbable obstacles and the unclimbable obstacles. Thus, even though the detection function of the detection sensor is failed or the detection sensor is malfunctioned, the robot cleaner may be stably driven. 
     Also, in the current embodiments, the caster for assisting the driving of the robot cleaner may be adjusted in height by the elasticity. Thus, when the robot cleaner passes over the obstacles, the impact applied to the robot cleaner may be reduced. 
     In addition, the detection sensor for detecting the obstacles such as the cliff or threshold may be provided as the semiconductor photo sensor. Also, the detection sensor may be disposed inside the sensor receiving groove which is recessed inward from the base. Thus, the amount of light incident into the detection sensor may be significantly changed according to whether the obstacles exist. Therefore, the performance of the detection sensor may be improved. 
     Thus, in the robot cleaner according to the embodiments, the structural drive suppression structure for improving the detection performance of the sensor and supplementing the malfunction of the sensor may be provided, and also, the impact applied to the robot cleaner when the robot cleaner passes over the obstacles may be significantly reduced. There, the drive stability of the robot cleaner may be improved.