A self-running robot tracking and imaging a human body with an inexpensive arrangement includes: first to fourth sensors; a camera; a driving device moving the first to fourth sensors and camera simultaneously; a rotary encoder detecting that the first to fourth sensors and camera have stopped; a control unit which, upon detection of a heat source by one of the first to fourth sensors, controls the driving device such that the camera turns to the direction which the sensor detecting the heat source faced, and controls the camera so as to image an object after the camera has stopped, and controls the driving device such that the first to fourth sensors remain stationary for 3 seconds after the camera has stopped irrespective of whether a heat source is detected.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a self-running robot, and particularly, to a self-running robot used to provide security.

2. Description of the Background Art

A conventional self-running robotic cleaner, such as that disclosed in Japanese Patent Laying-Open No. 06-098844 includes: a charge and power supply unit providing a direct voltage; a microprocessor that receives the direct voltage provided by the charge and power supply unit; a key input circuit that receives an action condition and an action command from a user to provide the action condition and the action command to the microprocessor; a thermal infrared radiation sensing circuit that senses thermal infrared radiation from a human body and a pet and provides a sense signal thereof to the microprocessor; a forward/backward movement motor driving circuit that receives a drive signal from the microprocessor to rotate a forward and backward motor thereby rotating a driving wheel either forward or backward; a steering motor driving circuit that receives a drive signal from the microprocessor to rotate a steering motor thereby changing the direction of advancement for the driving wheel; an ultrasonic wave transmission circuit that receives an ultrasonic wave signal from the microprocessor to transmit ultrasonic wave; an ultrasonic wave reception circuit that receives ultrasonic wave transmitted from the ultrasonic wave transmission circuit and reflected from an obstacle; and a cleaning motor driving circuit that receives a drive signal provided by the microprocessor based on a received signal to drive a cleaning motor to effect cleaning.

The above invention can reduce the production cost of a product and reduce the cleaning time, providing improved cleaning performance.

A conventional mobile robotic system, such as that disclosed in Japanese Patent Laying-Open No. 11-282533 includes a mobile robot that autonomously moves and performs tasks and a management device that directs the mobile robot to perform a task, the mobile robot including a control device that allows the robot to travel to the management device upon experiencing an external or internal influence, and an information transfer device that exchanges information with the management device.

According to the above invention, the mobile robot travels to the management device when a task of the mobile robot is to be interrupted or a task is to be started again from the beginning, facilitating the transfer of a direction by the management device to the mobile robot in the middle of a task. Moreover, information can also be transmitted from the mobile robot to the management device, thereby providing for the transfer to the management device of information on e.g. ambient situations including the presence of an obstacle obtained by the mobile robot, allowing the management device to issue corresponding directions or perform corresponding processes based on the information.

A conventional human detection arrangement, such as that disclosed in Japanese Patent Laying-Open No. 2002-350555 includes: a first sensor that senses the presence of a human within a first sensed area; and a second sensor that senses the presence of a human within a second sensed area smaller than the first sensed area, characterized in that the presence of a human within the first sensed area is sensed using the first sensor before sensing the presence of the human within the second sensed area using the second sensor to sense the direction of the human.

According to the above invention, the direction of the human can be determined in a simple manner.

Unfortunately, the inventions disclosed in Japanese Patent Laying-Open Nos. 06-098844 and 11-282533 do not provide easy tracking and sensing of the movement of a human body, since pyroelectric sensors are incapable of locating a human within the sensed areas.

The invention disclosed in Japanese Patent Laying-Open No. 2002-350555 requires higher manufacturing cost than is acceptable for a device merely for tracking and imaging a human body, since it fails to deal with noise generated during tracking and imaging of a human body.

SUMMARY OF THE INVENTION

The present invention attempts to solve the above problems. An object of the present invention, therefore, is to provide a self-running robot capable of tracking and imaging a human body with a simple arrangement.

To achieve the above object, a self-running robot according to an aspect of the present invention includes: a plurality of pyroelectric sensors detecting a heat source; a camera imaging an object on its optical axis; a driving device moving the plurality of pyroelectric sensors and camera simultaneously; a rotary encoder detecting that the plurality of pyroelectric sensors and camera have stopped; a first control device which, upon detection of the heat source by one of the plurality of pyroelectric sensors, controls the driving device such that the optical axis of the camera is in the direction which the pyroelectric sensor detecting the heat source faced; a second control device which controls the camera such that the camera images an object after the rotary encoder detects that the camera has stopped with its optical axis being in the direction which the pyroelectric sensor detecting the heat source faced; and a third control device which controls the driving device such that the plurality of pyroelectric sensors remain stationary for 3 seconds after the rotary encoder detects that the camera has stopped with its optical axis being in the direction which the pyroelectric sensor detecting the heat source faced, irrespective of whether the plurality of pyroelectric sensors detect a heat source.

Thus, just 3 seconds of standstill allows the camera to image an object using a simple arrangement while achieving accurate tracking by minimizing noise generated by the driving device moving the plurality of pyroelectric sensors simultaneously. Thus, a self-running robot may be provided capable of accurately tracking and imaging a human body using a simple arrangement.

A self-running robot according to another aspect of the present invention includes: a plurality of first detection sensors detecting a heat source; a camera imaging an object on its optical axis; a moving device moving the plurality of first detection sensors and camera simultaneously; a second detection sensor detecting that the plurality of first detection sensors and the camera have stopped; a first control device which, upon detection of the heat source by one of the plurality of first detection sensors, controls the moving device such that the optical axis of the camera is in the direction which that of the first detection sensors detecting the heat source faced; a second control device which controls the camera such that the camera images an object after the second detection sensor detects that the camera has stopped with its optical axis being in the direction which that of the first detection sensors detecting the heat source faced; and a third control device which controls the moving device such that the plurality of first detection sensors remain stationary for a predetermined time period after the second detection sensor detects that the camera has stopped with its optical axis being in the direction which that of the first detection sensors detecting the heat source faced, irrespective of whether the plurality of first detection sensors detect a heat source.

Thus, the camera can image an object with a simple arrangement while minimizing noise generated by the moving device moving the plurality of first detection sensors simultaneously. Thus, a self-running robot can be provided capable of tracking and imaging a human body with a simple arrangement.

It is desired that the plurality of first detection sensors include two or more sensors for detecting a heat source using the same construction. In addition, it is desired that the predetermined time period is not less than the time since the camera stops until the output of one of the two or more sensors is stabilized.

Thus, the camera can image an object with a simple arrangement while achieving accurate tracking by minimizing noise generated by the moving device moving the plurality of first detection sensors simultaneously. Thus, a self-running robot can be provided capable of accurately tracking and imaging a human object with a simple arrangement.

It is desired that the two or more sensors are pyroelectric sensors. In addition, it is desired that the time since the camera stops until the output of one of the two or more sensors is stabilized is 3 seconds.

That is, the two or more first detection sensors using the same construction are pyroelectric sensors. Thus, just 3 seconds of standstill allows the camera to image an object while achieving accurate tracking by minimizing noise generated by the moving device moving the plurality of first detection sensors simultaneously. Thus, a self-running robot can be provided capable of yet more accurately tracking and imaging a human body with a simple arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below referring to the figures. In the description below, the like components are labeled with the like designations and have the like names and functions as well. Thus, a detailed description thereof will not repeated.

A self-running robot according to a first embodiment of the present invention is described below.

Referring toFIGS. 1A,1B and2, a self-running robot110according to the present embodiment includes a first sensor112, a second sensor114, a third sensor116, a fourth sensor118, a timer120, a memory122, a control unit126, an input mechanism128, a camera130, an accumulator132, and a running mechanism134.FIGS. 1A and 1Bshow the external appearance of self-running robot110according to the present embodiment. Self-running robot110may be a disk-shaped robot that tracks and images an intruder in a user's home when the user is absent.FIG. 1Ais a plan view andFIG. 1Bis a bottom view of self-running robot110.FIG. 2is a control block diagram of self-running robot110.

First to fourth sensors112–118may be pyroelectric sensors detecting the presence of a heat source (typically a human body) and outputting a signal. First sensor112is provided on the left-front edge of self-running robot110; second sensor114is provided on the left-rear edge of self-running robot110; third sensor116is provided on the right-front edge of self-running robot110; and fourth sensor118is provided on the right-rear edge of self-running robot110. Four sensors are provided since one sensor can detect a heat source in a range of 100 degrees with respect to the sensor. Timer120outputs a signal after the passage of a predetermined period. Memory122stores information needed for controlling various components of self-running robot110. A brightness sensor124detects the brightness in the environment of self-running robot110. Brightness sensor124provides control unit126with a signal indicating a value for the brightness in the environment. Control unit126controls various components of self-running robot110. Control unit126also performs operations needed for the control. Input mechanism128accepts the user's operations by receiving a signal. Camera130images an object that is located on its optical axis. In the present embodiment, camera130employs a charge-coupled device (CCD). A filter is provided in front of the lens of camera130. Camera130automatically mounts and removes the filter based on the value provided by brightness sensor124, which allows camera130to function as a normal digital camera in bright environment and as an infrared camera in dark environment. Camera130is provided on the front of self-running robot110. Accumulator132accumulates electric power. Running mechanism134generates a propelling power that enables self-running robot110to navigate.

Running mechanism134includes a motor160, a driving device162, a rotary encoder164, and a gyro sensor166. Motor160consumes electric power to rotate a rotor. Driving device162conveys the torque of the rotor to the surface of the floor, allowing self-running robot110to travel on the floor. Driving device162moves simultaneously first to fourth sensors112–118and camera130. Rotary encoder164generates a pulse according to the rotation of driving device162. Rotary encoder164of the present embodiment is an increment-based rotary encoder. The generated pulse is output to control device126to allow it to determine the speed for driving device162based on the presence of the pulse and the number of pulses per unit time. Thus, rotary encoder164detects when first to fourth sensors112–118and camera130stop. Gyro sensor166detects, independently from rotary encoder164, whether driving device162is rotated, i.e. gyro sensor166detects when first to fourth sensors112–118and camera130stop similar to rotary encoder164.

Driving device162includes a driving wheel (right)172, a driven wheel174and a driving wheel (left)176. Driving wheel (right)172and driving wheel (left)176constitute a crawler that receives motion from motor160to generate a propelling power. Driven wheel174follows the movement of right and left driving wheels172and176. Driven wheel174is fixedly mounted to face a certain direction. Thus, driven wheel174slides on the floor as self-running robot110spins. To reduce the frictional resistance against the sliding on the floor, the edge of driven wheel174is rounded and is made of resin (in the present embodiment, the wheels are made of nylon, although urethane, for example, may also be used).

Referring toFIG. 3, a program executed on self-running robot110according to the present embodiment performs the following operations for imaging an intruder:

At step100(a step is hereinafter indicated by S), control unit126obtains a signal from first to fourth sensors112–118.

At S102, control unit126determines if one of first to fourth sensors112–118has detected a human body. If so (YES at S102), the process moves to S104. Otherwise (NO at S102), the process returns to S100.

At S104, control unit126determines if only first sensor112has detected a human body. If so (YES at S104), the process moves to S106. Otherwise (NO at S104), the process moves to S108. At S106, motor160is rotated under the pulse-width modulation (PWM) control of control unit126. The rotation of motor160causes driving wheel (right)172to generate a backward propelling power. Driving wheel (left)176generates a forward propelling power. Self-running robot110turns to the direction which first sensor112originally faced.

At S108, control unit126determines if only second sensor114has detected a human body. If so (YES at S108), the process moves to S110. Otherwise (NO at S108), the process moves to S112. At S110, motor160is rotated under the PWM control of control unit126. The rotation of motor160causes driving wheel (right)172to generate a backward propelling power and driving wheel (left)176to generate a forward propelling power. Self-running robot110turns to the direction which second sensor114faced.

At S112, control unit126determines if only third sensor116has detected a human body. If so (YES at S112), the process moves to S114. Otherwise (NO at S112), the process moves to S116. At S114, motor160is rotated under the PWM control of control unit126. The rotation of motor160causes driving wheel (right)172to generate a forward propelling power and driving wheel (left)176to generate a backward propelling power. Self-running robot110turns to the direction which third sensor114faced.

At S116, control unit126determines if only fourth sensor118has detected a human body. If so (YES at S116), the process moves to S118. Otherwise (NO at S116), the process moves to S120. At S118, motor160is rotated under the PWM control of control unit126. The rotation of motor160causes driving wheel (right)172to generate a forward propelling power and driving wheel (left)176to generate a backward propelling power. Self-running robot110turns to the direction which fourth sensor118faced.

At S120, control unit126determines if two or more of first to fourth sensors112–118have detected a human body. If so (YES at S120), the process moves to S124. Otherwise (NO at S120), the process returns to S100.

At S122, control unit126outputs a signal after driving device162has stopped. Control unit126determines that driving unit162has stopped when one of the following two requirements is met. One requirement is that rotary encoder164no longer outputs a pulse. The other requirement is that rotary encoder164outputs an abnormal pulse and gyro sensor166detects the stopping of driving device162. In determining if driving device162has stopped, the result from rotation encoder164is prioritized. When control unit126outputs the signal, camera130images an object located in front of it. Camera130provides data of the taken image to control unit126, which stores the image data in memory122. Thus, control unit126controls camera130such that camera130images an object after rotary encoder164or gyro sensor166has detected that camera130has stopped with its optical axis being in the direction which that of first to fourth sensors112–118detecting the heat source faced.

At S124, timer120outputs, after the passage of a predetermined time period, a signal to control unit126indicating the expiration of the time period. Control unit126suspends its operations until the signal is output. Thus, control unit126controls driving device162such that first to fourth sensors112–118remain stationary for a predetermined period after rotary encoder164or gyro sensor166detects that camera130has stopped with its optical axis in the direction which that of first to fourth sensors112–118detecting a heat source faced, irrespective of whether first to fourth sensors112–118detect a heat source. In the present embodiment, a “predetermined period” is 3 seconds, which value was derived from the fact that the optimal value obtained from experiments (i.e. the minimum time for one of first to fourth sensors112–118to be stabilized; a malfunction is often encountered directly after a movement of first to fourth sensors112–118due to heat fluctuation) was 3 seconds.

At S126, control unit126determines if input mechanism128received a signal indicating that monitoring should be terminated. If so (YES at S126), the process ends. Otherwise (NO at S126), the process moves back to S100.

Now, operations of self-running robot110of a structure as described above based on the above flowchart will be described.

Self-running robot110is in a halt state when it begins the monitoring of an intruder. Control unit126obtains a signal from first to fourth sensors112–118(S100). Upon obtaining the signal, control unit126determines if one of first to fourth sensors112–118has detected a human body (S102). Assume that only first sensor112, located at the left-front, has detected a human body. Since control unit126determines that one of first to fourth sensors112–118has detected a human body (YES at S102), control unit126then determines if only first sensor112has detected a human body (S104). In this example, it is determined that only first sensor112has detected a human body (YES at S104), such that motor160is rotated under the PWM control of control unit126. Thus, upon detection of a heat source by one of first to fourth sensors112–118, control unit126controls driving device162such that the optical axis of camera130is in the direction which the sensor detecting the heat source faced. Driving device162of self-running robot110causes the robot to spin to the direction which first sensor112faced (to the left as viewed upon the front of self-running robot110) (S106). Once driving device162is rotated and halted and control unit126outputs a signal, camera130images an object in front of it (S122). Once the object is imaged, timer120outputs, after the passage of a predetermined time period, a signal to control unit126indicating the expiration of the time period (S124), which causes self-running robot110to remain stationary for the predetermined period after the spinning using driving device162. The robot should remain stationary because a moving pyroelectric sensor might detect a fluctuation of ambient heat and erroneously outputs a signal indicating the presence of a heat source, even when there is no heat source nearby. Once a signal is output indicating the expiration of the time period, control unit126determines if input mechanism128has received a signal indicating that monitoring should be terminated (S126). If not (NO at S126), the process from S100to S126is repeated until a signal is received indicating the termination of monitoring.

Thus, self-running robot110according to the present embodiment includes a plurality of pyroelectric sensors mounted on it and waits in a halt state for a detection of a human body. If one of the sensors detects a human body (or it may detect an animal other than human; such applies to the following and to the second embodiment), the robot automatically turns to the direction which that sensor faced, and images the human body. When it is to continue to turn, it waits for a while and then tries to detect a human body again. Thus, a self-running robot can be provided capable of tracking and imaging a human body with an inexpensive arrangement.

It should be noted that first to fourth sensors112–118may be provided on the sides of self-running robot110.

Further, first to fourth sensors112–118may be other sensors than pyroelectric sensors. In this case, the “predetermined period” in S124may be any time period that is equal to or longer than the time from the completion of a movement of first to fourth sensors112–118to the stabilization of the output of all of first to fourth sensors112–118.

Also, at S124, timer120may output a signal to control unit126indicating the expiration of the time period after camera130has stopped and the output of one of first to fourth sensors112–118has been stabilized. The applicability of such requirement is derived from the fact that first to fourth sensors112–118are located such that two or less sensors can detect a heat source located at one point and three or more sensors are provided. Typically, there is only one intruder encountered. If only one intruder is detected by two or less sensors, there is at least one sensor that cannot detect the presence of the intruder. This sensor's output is not affected by heat generated by the intruder, and generally originates from heat fluctuation. These considerations mean the following: firstly, when one sensor's output is stabilized, it can be estimated that another sensor's output is also stabilized; secondly, when one sensor's output is stabilized and, at the same moment, another sensor's output is not stabilized, such instability is due to the presence of a heat source (i.e. intruder). Thus, an attempt to detect a heat source can be initiated directly after the output of one of first to fourth sensors112–118has reached a constant value in order to prevent a malfunction and allow quick detection of the presence of an intruder.

A self-running robot according to a second embodiment of the present invention will be described below.

Self-running robot110according to the present embodiment has the same hardware configuration as the first embodiment described above and has the same functions as well. Accordingly, a detailed description thereof will not be repeated.

Referring toFIG. 4, a program executed on self-running robot110according to the present embodiment performs the following operations for imaging an intruder. Note that in the flowchart shown inFIG. 4, those operations that have been discussed above referring toFIG. 3are labeled with the same step numbers and are the identical operations. Accordingly, a detailed description thereof will not be repeated.

At S130, control unit126recognizes a human face in the image taken by camera130. In the present embodiment, those of the pixels are extracted having a difference in tone from the surrounding pixels larger than a threshold (arbitrarily given by the designer of self-running robot110) and a template matching is executed between the arrangement of such pixels and ellipses, and it is determined that a human face is imaged when the degree of matching is above a threshold (again arbitrarily given by the designer of self-running robot110), where the center of the face is considered to be at the center coordinates of a template with a degree of matching above the threshold. In the present embodiment, image recognition is executed using different template ellipse sizes.

At S131, control unit126determines if it recognized a human face. If so (YES at S131), the process moves to S132. Otherwise (NO at S131), the process moves to S136. At S132, control unit126calculates the difference in coordinates between the center of the human face in the image and the center of the entire image.

At S134, control unit126controls motor160such that the center of the human face in the image lies on the vertical centerline of the entire image. Motor160causes the robot to spin under the control of control unit126. Prior to this, the distance from the intruder needs to be measured to calculate the angle φ at which the robot should turn, a method of which will be described below.

At S136, control unit126determines if input mechanism128has received a signal indicating that monitoring should be terminated. If so (YES at S136), the process ends. Otherwise (NO at S136), the process returns to S122.

Operations of self-running robot110of a structure as described above based on the above flowchart will be described below.

After the operations in S100–118, control unit126recognizes a human face in the image taken by camera130(S130). If control unit126recognizes a human face, it calculates the difference in coordinates between the center of the human face in the image and the center of the entire image (S132). Once the difference in coordinates is found, control unit126controls motor160such that the center of the human face in the image lies on the vertical centerline of the entire image. Motor160causes the robot to spin under the control of control unit126(S134). For this purpose, control unit126uses the following procedure to measure the distance from the intruder and calculates the needed amount of movement (the angle φ at which self-running robot110should turn).

A first step is to calculate the difference in coordinates (in this case, the difference in the horizontal coordinate C) between the position of the center of the human face in the most recently taken image (first image) and the position of the center of the human face in an image taken directly before the first image was taken (second image).

A second step involves substituting the angle θ at which self-running robot110turned directly before the first image was taken (which angle is stored in memory122) into the following equation to calculate the distance R between the intruder and self-running robot110at the moment when the second image was taken:
0.5C=Rsin(0.5θ)  (1)

In the second step, the distance R calculated after the second image was taken (this distance R is referred to as “R (2)”) and the distance R calculated for the first image (this distance R is referred to as “R (1)”) are used to calculate the estimated distance R (0) between the intruder and self-running robot110at the moment of a next imaging.

A third step involves substituting the difference in the horizontal coordinate, S, calculated at S132and the estimate R (0) into the following equation to calculate the angle φ at which self-running robot110is to turn:
0.5S=R(0)sin(0.5φ)  (2)

A fourth step is to store in memory122the center coordinates of the human face in the first image, distance R (1) and angle φ to be used to subsequently calculate an angle φ, for example. If the angle φ is to be calculated first, the first and second steps are not performed. Instead, at the third step, a value pre-stored as initial value in memory122is used as the estimate R (0) which is substituted into equation (2) to calculate the angle φ.

Once the angle φ was calculated, control unit126determines if input mechanism128has received a signal indicating that monitoring should be terminated. If not (NO at S136), the operations in S122–136are repeated until control unit126determines that a signal has been received indicating the termination of monitoring.

Thus, a self-running robot according to the present embodiment includes a plurality of pyroelectric sensors mounted thereon and waits in a halt state for a detection of a human body. When one of the sensors detects a human body, the robot automatically rotates to the direction which that sensor faced and images the human body. Further, image recognition allows the recognition, tracking and imaging of an intruder. Thus, a self-running robot can be provided capable of tracking and imaging a human body with an inexpensive arrangement.

A self-running robot according to a third embodiment of the present invention will be described below.

Referring toFIG. 5, a self-running robot210according to the present embodiment includes a first sensor112, a second sensor114, a third sensor116, a fourth sensor118, a timer120, a memory232, a control unit126, an input mechanism128, a complementary metal-oxide-semiconductor (CMOS) camera240, an accumulator132, and a running mechanism134.

Memory232stores similar information to that stored in memory122of the first embodiment and, in addition, a data table indicating directions to which self-running robot210is to turn (hereinafter referred to as “data table”). The directions shown inFIG. 6are those as viewed by a person opposite the front side of self-running robot210. Referring toFIG. 6, the data table contains data indicating different combinations of detection and non-detection of a human body by the sensors and data indicating the directions to which self-running robot210is to turn. In the data table, the various combinations of detection and non-detection of a human body by the sensors are associated with the respective directions to which self-running robot210is to turn.

CMOS camera240images an object on its optical axis. CMOS camera240uses a CMOS device. A filter is provided in front of the lens of CMOS camera240. CMOS camera240automatically mounts and replaces the filter based on the value provided by brightness sensor124, which allows CMOS camera240to function as a normal digital camera in bright environment and as an infrared camera in dark environment. CMOS camera240is provided on the front of self-running robot110.

Other hardware components are the same as in the first embodiment described above and their functions are the same, as well. Accordingly, a detailed description thereof will not be repeated.

Referring toFIG. 7, a program executed on self-running robot210performs the following operations for imaging an intruder. In the flowchart shown inFIG. 7, those operations that have been discussed above referring toFIG. 3are labeled with the same step numbers and are the identical operations. Accordingly, a detailed description thereof will not be repeated.

At S142, control unit126references the data table stored in memory232to specify the direction to which self-running robot210should turn.

At S144, motor160is rotated under the PWM control of control unit126. The rotation of motor160causes right and left driving wheels172and176to rotate such that self-running robot210turns to the direction specified at S142.

At S146, control unit126outputs a signal after driving device162has stopped. Control unit126determines that driving device162has stopped when one of the following two requirements is met. One requirement is that rotary encoder164no longer outputs a pulse; the other requirement is that rotary encoder164outputs an abnormal pulse and gyro sensor166detects the stopping of driving device162. In determining if driving device162has stopped, the result from rotary encoder164is prioritized. When control unit126outputs the signal, CMOS camera240images an object located in front of it. CMOS camera240provides data of the taken image to control unit126which stores the image data in a memory232. Thus, control unit126controls CMOS camera240such that CMOS camera240images an object after rotary encoder164or gyro sensor166detects that CMOS camera240has stopped with its optical axis in the direction which that of first to fourth sensors112–118detecting a heat source faced.

Operations of self-running robot110of a structure described above based on the above flowchart will be described below.

After the operations in S100–116, control unit126determines if two or more of first to fourth sensors112–118have detected a human body (S120). If so (YES at S120), control unit126references the data table stored in memory232to specify the direction to which self-running robot210should turn (S142). Once the turn direction for self-running robot210was specified, right and left driving wheels172and176are rotated such that self-running robot210turns to the direction specified at S142(S144). Once self-running robot210has turned, control unit126outputs a signal after driving unit162has stopped. When control unit126outputs the signal, CMOS camera240images an object in front of it (S146).

Thus, a self-running robot according to the present embodiment includes a plurality of pyroelectric sensors mounted thereon and waits in a halt state for a detection of a human body. When one of the sensors detects a human body (or an animal other than human), the robot references a data table to automatically turn to a predetermined direction for imaging the human body. If it is to continue to turn, it waits for a while and then tries to detect a human body again. Thus, a self-running robot can be provided capable of tracking and imaging a human body with an inexpensive arrangement.