JP2006190105A - Mobile robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile robot capable of automatically detecting a step without contact and selecting a method of riding over the step according to the kind of step. <P>SOLUTION: The body frame 10 of the mobile robot is moved over a runway by means of drive wheels 6, 12. A first driven wheel 30 is provided in front along the direction of travel of the body frame. A second driven wheel 32 is provided therebehind. The distance in the direction of travel of the body frame is detected by a distance sensor part 28 that observes the runway at a certain elevation angle. The body frame is provided with a first vertical movement mechanism for moving the first driven wheel and the distance sensor integrally on the body frame while keeping the elevation angle roughly constant, and a second vertical movement mechanism for moving the second driven wheel vertically. Any step on the runway is detected based upon a distance signal from the distance sensor part, and the first and second vertical movement mechanisms are moved vertically as the body frame moves. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

    The present invention relates to a mobile robot provided with a moving mechanism such as a wheel or a crawler, and more particularly to a mobile robot that detects a step while moving and gets over the step if the step can be overcome.

  Conventionally, a leg wheel type is often used for a mobile robot capable of getting over a step. In this leg-wheel type step-over robot, after detecting a step, the height and depth are measured once stopped, and then whether or not it is possible to get over is judged and the stairs are continuously passed.

  As disclosed in Non-Patent Document 1, as another mobile robot, a mobile robot having wheels as moving mechanisms on the left and right sides of a main body is known. In this mobile robot, when moving by a wheel, the movement is assisted by a driven wheel caster fixed to the main body, and surrounding obstacles are detected in a non-contact manner by a detector emitting ultrasonic waves fixed to the upper part of the main body. While traveling.

  This mobile robot measures the distance from the moving floor surface to an obstacle of a certain height or more by the detection unit, and takes an action of avoiding the obstacle by a drive control unit that controls driving of the wheels. For obstacles or steps on the floor, the obstacle passing performance is determined by the radius of the wheel used for the driven wheel caster.

On the other hand, as disclosed in Patent Document 1 and Patent Document 2 as other mobile robots, two contacts for detecting an obstacle at the front part of the main body are provided with wheels as moving mechanisms on the left and right of the mobile robot main body. 2. Description of the Related Art Mobile robots are known in which a type of switch sensor is arranged to determine whether an obstacle can be climbed over. The wheels and the crawler are controlled so that the wheels are used for the movement and the crawler and the moving mechanism are used for the movement according to the determination result of whether or not the boarding is possible.
JP2002-366226 JP2004-021895 ApriAlpha (Matsuniraku et al .: Development of service robots using distributed object technology, Proceedings of Lectures of Robot Mechatronics '03, 1A1-3F-C5, (2003))

  In the leg-wheel type, the mobile robot temporarily stops with respect to an unknown step, and after the condition is measured, the traversing operation starts, so the vehicle travels stably, but there are steps continuously. In some cases, there is a problem that the movement is not efficient.

  In the mobile robot disclosed in Non-Patent Document 1, an obstacle in front is detected during movement and an avoidance action is taken so as not to collide. However, information on the height and depth of the obstacle on the floor surface is taken. Since the vehicle travels without being obtained, and the driven wheel is fixed to the main body, there is a problem that it is not possible to get over an obstacle higher than the wheel diameter of the driven wheel. . In addition, there is also a problem that the mobile robot body is greatly inclined and unstable even when getting over.

  In the mobile robot disclosed in Patent Document 1, since the switch sensor contacts and detects the obstacles in general, the obstacle detection becomes a disturbance of the movement control, and the obstacles can be avoided. There is a problem that cannot move stably. In addition, since the moving mechanism is switched by judging whether or not the vehicle can get over after the collision with the obstacle by the switch sensor, there is a problem that the movement is not efficient.

  The present invention has been made in view of the circumstances as described above, and its purpose is to detect obstacles in a non-contact manner without colliding with the obstacles, and whether or not the obstacles can be climbed while moving. It is an object of the present invention to provide a mobile robot in which a control method is determined promptly and can move over obstacles stably and efficiently.

According to this invention,
Body frame,
Driving wheels for moving the main body frame on the road,
A first driven wheel provided forward with respect to the running direction of the main body frame;
A distance sensor unit for detecting a distance in the running direction of the main body frame at a certain depression angle;
A first vertical movement mechanism that vertically moves the first driven wheel and the distance sensor integrally on the main body frame while maintaining the depression angle substantially constant;
A control unit that detects a step on a road based on a distance signal from the distance sensor unit and moves the first vertical movement mechanism up and down along with the movement of the main body frame;
A mobile robot characterized by comprising: is provided.

The mobile robot is
A second driven wheel provided rearward with respect to the traveling direction of the main body frame;
A second vertical movement mechanism for moving the second driven wheel up and down;
The control unit may actuate the second vertical movement mechanism together with the movement of the main body frame corresponding to the step detected based on a distance signal from the distance sensor unit.

  As described above, there is provided a mobile robot that can automatically detect a level difference in a non-contact manner and select a boarding method according to the level difference.

  Hereinafter, a mobile robot according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 and FIG. 2 are a side view schematically showing a mobile robot according to one embodiment of the present invention and a back view showing a back structure thereof. As shown in FIG. 1, a control unit 8 for controlling the mobile robot is placed and fixed on a substantially disc-shaped main body frame 10. The main body frame 10 is placed on driving wheels 6 and 12 as a moving mechanism. As shown in FIG. 2, the main body frame 10 is formed with notches where the drive wheels 6 and 12 are arranged, and the upper portions of the drive wheels 6 and 12 protrude above the main body frame 10 through the notches. . Motors 36 and 34 are fixed to the rear surface of the main body frame 10 so that the motor shafts 4 and 14 are arranged in the same straight line, and driving wheels 6 and 12 are attached to the motor shafts 4 and 14 by the motors 36 and 34. It is fixed to be rotated. Therefore, when the motors 36 and 34 are driven, the drive wheels 6 and 12 are rotated, and the main body frame 10 travels in the direction indicated by the arrow F. Here, since the drive wheels 6 and 12 are independently driven by the motors 36 and 34, respectively, the rotational speed of one of the motors 34 and 36 is increased so that the drive wheels 6 and 12 are turned toward the side with the lower rotational speed. The Rukoto. That is, when the rotation speed of the motor 34 corresponding to the right wheel 12 is increased, the main body frame 10 is traveled so as to be directed to the left side, and when the rotation speed of the motor 36 corresponding to the left wheel 6 is increased, the main body frame. 10 is run so as to be directed to the right side.

  It should be noted that in FIG. 1, the rear of the wheel 12 is shown in a transparent manner in order to clearly show the structure of the back surface of the wheel 12.

  Brackets 16 and 18 for supporting and fixing the first and second support legs 20 and 22 are fixed to the back surface of the main body frame 10 so as to protrude toward the running surface. And one end of the 1st and 2nd link arms 24-1, 24-2, 26-1, and 26-2 of the 2nd support legs 20 and 22 is being fixed so that rotation is possible. The other ends of the first and second link arms 24-1 and 24-2 of the support leg 20 are rotatably connected to the bracket 25, and a distance sensor unit 28 is placed on the bracket 25. Yes. A driven wheel 30 as an auxiliary wheel is fixed to the bracket 25. The other ends of the first and second link arms 26-1 and 26-2 of the support leg 22 are similarly connected to a bracket 27 so as to be rotatable, and this link 27 is similarly connected to a driven wheel as an auxiliary wheel. 30 is fixed. The driven wheels 30 and 32 are pivotally supported around the brackets 25 and 27 while being rotatable in the moving direction indicated by the arrow F. The distance from the driven wheels 30 and 32 to the main body frame 10 is set to be substantially equal to the distance from the ground contact surface to the travel path of the drive wheels 6 and 12 to the main body frame 10 so that the main body frame 10 travels flat. As long as the vehicle is driven on the road by the drive wheels 6, 12, the main body frame 10 is always maintained substantially parallel to the road by the driven wheels 30, 32.

  Support rotary shafts 52 and 54 are fixed to one ends of the first link arms 24-1 and 26-1 constituting the first and second support legs 20 and 22, respectively. Each is rotatably supported and connected to gears 44 and 46. The gears 44 and 46 are connected to motor gears 56 and 58 of link drive motors 38 and 40 fixed on the main body frame 10 via rotating belts 48 and 50. When the motor gears 56 and 58 of the link drive motors 38 and 40 are rotated, the rotation is transmitted to the gears 44 and 46 through the rotating belts 48 and 50, and the first link arm 24 is rotated together with the rotation of the gears 44 and 46. -1 and 26-1 are swung (rotated). The second link arms 24-2 and 26-2 are connected to the first link arms 24-1 and 26-1 by the brackets 25 and 27 so as to be parallel to each other. As the link arms 24-1 and 26-1 are rotated, the second link arms 24-2 and 26-2 connected by the brackets 25 and 27 become the first link arms 24-1 and 26-26. 1 is swung (rotated) in parallel.

  Since link drive motors 38 and 40 are provided corresponding to the first and second support legs 20 and 22, respectively, the first and second support legs 20 and 22 can swing independently, By controlling the rotation direction of the link drive motors 38 and 40, the other ends of the first and second support legs 20 and 22 are moved upward or downward. That is, the first and second support legs 20 and 22 can be raised or lowered independently. Therefore, the first support leg 20 can be raised and the second support leg 22 can be maintained or lowered. Also, the first support leg 20 can be lowered and the second support leg 22 can be maintained or raised. When one of the first and second support legs 20 and 22 is lifted and the corresponding driven wheels 30 and 32 are lifted together with this one and separated from the travel path, the other driven wheels 30 and 32 and the drive wheels 6 and 12 are driven. When the main body frame 10 is supported and the main body frame 10 is in the running state, the main body frame 10 is moved by the other driven wheels 30 and 32 and the drive wheels 6 and 12.

  As is clear from FIG. 2, the first and second support legs 20, 22 are provided on the main body frame 10 so that the first and second support legs 20, 22 can be raised onto the main body frame 10. A notch through which 22 can pass is provided. Further, the driven wheels 30 and 32 are allowed to rotate only along the traveling direction F, and the gear mechanism that allows the driven wheels 30 and 32 to rotate only in one direction so as not to rotate in the direction opposite to the traveling direction F. Alternatively, it is preferable to provide a reverse rotation prevention mechanism such as a clutch mechanism. As the reverse rotation prevention mechanism such as a clutch mechanism, a control mechanism such as an electromagnetic clutch that can be controlled by the control unit 8 so as to prevent reverse rotation when necessary may be used. The driven wheels 30, 32 that rotate along the traveling direction in the driven wheels 30, 32 can rotate around the brackets 25, 27 as the main body frame 10 turns, but are in a spherical shape such as a ball caster. When a rotating mechanism that can rotate in all directions is employed as the driven wheels 30 and 32, it does not have to be rotated around the brackets 25 and 27.

  The control unit 8 shown in FIG. 1 includes a circuit as shown in FIG. That is, a distance detection signal from the distance sensor unit 28 is output to the interface 70, A / D converted by the interface 70, and supplied to the CPU 72 as a sensor signal. The shaft outputs of the motors 34 and 36 are detected by encoders 62 and 64 provided in the motors 34 and 36, and the outputs from the encoders 62 and 64 are supplied to the CPU 72 via the interface 70 as counter signals. The counter signal is counted by the CPU 72, and by counting the counter signal, the travel distance of the main body frame 10 accompanying the rotation of the drive wheels 6, 12 depending on the rotation of the wheel drive motors 34, 36 is detected. Further, by obtaining the difference in rotation between the wheel drive motors 34 and 36, the main body frame 10 is turned and the change direction angle of the main body frame is determined. Therefore, the CPU can grasp the traveling position of the mobile robot by inputting the initial position coordinates of the mobile robot in advance. Similarly, the shaft outputs of the motors 38 and 40 are detected by an encoder 64 provided in the motors 38 and 40, and the output from the encoder 64 is supplied as a counter signal to the CPU 72 via the interface 70. The counter signal is counted by the CPU 72, and the ascending or descending position of the support legs 20, 22 determined depending on the rotation of the link driving motors 38, 40 is detected.

  The CPU 72 generates a drive signal in response to an input such as a target value from the external input unit 74 and supplies the drive signal to the motor driver 66 via the interface 70. Accordingly, the motors 34 and 36 are energized by the motor driver 66, the drive wheels 6 and 12 are rotated toward the target, and the main body frame 10 moves. The CPU 72 detects an obstacle or a step in the traveling direction according to the sensor signal, generates a preprogrammed drive signal, and supplies the drive signal to the motor driver 68 via the interface 70. Accordingly, the motors 38 and 40 are energized by the motor driver 66 and the support legs 20 and 22 are raised or lowered toward the target, so that the main body frame 10 travels over obstacles or steps as described later. Drive on the road.

  The distance sensor unit 28 includes a light emitting element (not shown) such as a laser diode or a light emitting diode that irradiates a light beam toward the running surface, and an optical sensor (not shown) that detects a light beam reflected from the running surface. Has been. Even if the support leg 20 is moved up and down, the distance sensor unit 28 is always separated from the traveling surface by a constant observation distance L0 at a constant depression angle without changing its posture with respect to the traveling surface. The running surface will be observed. That is, as shown in FIG. 4A, in the state where the support legs 20 and 22 are arranged substantially parallel to the travel path, the mobile robot travels on a flat travel path, and a light beam is emitted on the travel path. The light is irradiated from the distance sensor unit 28 at a predetermined depression angle θ, the light beam is reflected from the traveling path of the light beam to the distance sensor unit 28, the reflected light beam is received by the distance sensor unit 28, and the light intensity is detected. While the light intensity of the reflected light is constant, the distance sensor unit 28 always observes the constant observation distance L0. In the state where the support legs 20 and 22 are arranged substantially parallel to the traveling path, when the light beam is directed to the step as shown in FIG. 4A, the light beam reflected from the side surface of the step is a distance sensor. Detected by the unit 28. Therefore, the distance sensor unit 28 detects a reflected light beam having a greater light intensity than when observing the observation distance L0 and detects the distance (L0−ΔL). The intensity of the reflected light beam detected by the distance sensor unit 28 increases depending on the height H of the side surface of the step, and the mobile robot travels and the threshold distance (L0) is set between the distance sensor unit 28 and the side surface of the step. -ΔL = Lth) and the intensity of the reflected light beam exceeds a predetermined threshold value, the link drive motor 38 is activated and the support leg 20 starts to rise. Before the support leg 20 is raised to the highest position, the distance sensor unit 28 observes the traveling road on the step as shown in FIG. Therefore, the distance sensor unit 28 again observes the predetermined observation distance L0 at the predetermined depression angle θ.

  As shown in FIG. 4C, when the step width W is short, even if the distance sensor unit 28 temporarily observes the flat surface of the step and detects the observation distance L0, the distance sensor unit 28 thereafter. May irradiate the light beam beyond the step and detect a flat traveling path lower than the step. In such a case, the distance sensor unit 28 observes a distance (L0 + ΔL) farther than the observation distance L0, and the mobile robot detects the flat surface of the step from the travel distance W of the step. Can be detected in advance. Therefore, this step can be overcome by a pre-programmed step-up or step-over operation.

  FIG. 5 shows a graph showing the relationship between the detected observation distance L detected by the distance sensor unit 28 and the travel distance of the mobile robot. FIGS. 6A to 7G show the change in the posture of the mobile robot and the operation of the support legs 20 and 22 accompanying the movement of the mobile robot.

  Since there is no step while the mobile robot is moved to the distance D1 shown in FIG. 5, as shown in FIG. 6A, the main body frame 10 is maintained substantially parallel to the travel path. The observation distance L of the distance sensor unit 28 is maintained at the observation distance L0. As shown in FIG. 5, when the step is detected at the movement distance D1, the observation distance L becomes shorter than the predetermined observation distance L0, and the distance (L0−ΔL) is detected. Thereafter, the support leg 20 is raised as shown in FIG. 6B, and the distance sensor unit 28 temporarily detects the observation distance L0 as shown in FIG. As shown in FIG. 6C, when the driving wheels 6 and 12 are brought into contact with the step and move on to the step at the moving distances D2 to D3, the posture of the main body frame 10 itself is slightly disturbed. Therefore, as shown in FIG. 5, the observation distance of the distance sensor unit 28 is rapidly increased at the movement distances D2 to D3. At the moving distances D3 to D4, as shown in FIG. 6 (d), the driving wheels 6 and 12 are completely on the flat part on the step and the support leg 20 is lowered so that the driven wheel 30 is put on the flat part on the step. It is done. During this time, as shown by the movement distances D3 to D4 in FIG. 5, the observation distance of the distance sensor unit 28 is rapidly reduced. Thereafter, in order not to raise the support leg 22 and bring the driven wheel 32 on the rear side into contact with the step, the main body frame 10 is maintained in the forward tilted state as shown in FIGS. 7 (e) and (f). The driven wheel 32 is raised. That is, first, as shown in FIG. 7E, the support leg 20 is slightly raised, the support leg 22 is temporarily lowered, and the main body frame 10 is tilted forward. Next, as shown in FIG. 7 (f), with the main body frame 10 maintained in the forward tilted posture, the support leg 22 is raised and the driven wheel 32 is moved on the step as the mobile robot moves. . In the forward tilt posture shown in FIGS. 7E and 7F, the distance sensor unit 28 observes an observation point at a position closer to the observation distance L0. Therefore, the movement distance D3 in FIG. As shown in ~ D4, the observation distance becomes smaller than the distance L0. Thereafter, as shown in FIG. 7 (g), the support leg 22 is lowered on the step and the support leg 20 is raised so that the main body frame 10 moves from the forward tilted posture while being substantially parallel to the traveling path on the step. The robot continues to run. Therefore, as shown in FIG. 5, in the travel distances D5 to D6, the observation distance L0 is detected as in the travel distances 0 to D1.

  As shown in FIG. 8, when the mobile robot steps down the step, it is operated as follows. When the distance sensor unit 28 detects a distance (L + ΔL) that is longer than the observation distance L0 by the movement distances D6 to D7, the flat part ends and a surface lower than the flat part is observed. When the mobile robot moves forward and the driven wheel 30 passes through the step, the support leg 20 of the main body frame 10 is lowered and the driven wheel 30 is landed on a flat road below the step. The main body frame 10 is maintained substantially parallel to the step surface. Here, with the landing of the driven wheel 30, the distance sensor unit 28 observes the normal observation distance L0 at the movement distances D8 to D9. As shown in FIG. 8, when the drive wheels 6 and 12 reach a step, the support leg 20 is gradually raised as the drive wheels 6 and 12 descend the step, and the support leg 22 is also raised in a similar manner so that the main body frame 10 is slightly lifted. It is moved from the upper surface of the step toward the lower surface while being inclined backward. At this time, since the main body frame 10 is slightly tilted backward, the observation distance is slightly longer than the distance L0 at the movement distances D9 to D10 as shown in FIG. When the driving wheels 6 and 12 start moving down the flat surface by moving down the step and the driven wheel 32 passes through the step, the support leg 22 is lowered. Accordingly, the mobile robot is moved while the main body frame 10 is maintained substantially parallel to the traveling surface. Therefore, the distance sensor unit 28 detects the approximate distance L0 after the moving distance D10.

  The mobile robot is not only a step having a sufficient movement distance compared to the drive wheels 6 and 12 as shown in FIGS. 6, 7 and 8, but also a comparison as shown in FIGS. Even small steps with a target width W can be overcome smoothly. 4C and 9C, the operation up to approaching the step is the same as that shown in FIGS. 6A to 6C. When the step width W is smaller than the arm length of the support legs 20 and 22, the driven wheels 30 do not descend on the step when the driving wheels 6 and 12 come into contact with the step. It is lowered toward the bottom. When the drive wheels 6 and 12 come into contact with the step, the support legs 20 and 22 are lowered as shown in FIG. 9, and the drive wheels 6 and 12 are supported by the driven wheels 30 and 32 as they move and ride on the step. When the drive wheels 6 and 12 are lowered from the step, the support legs are gradually raised and similarly supported by the driven wheels 30 and 32 to drive the drive wheels 6 and 12 to the surface below the step. After the drive wheels 6 and 12 are lowered, the support legs 22 are raised and the support legs 22 are lowered when the driven wheels 32 exceed the level difference and are again shown in FIG. 4 (a) or FIG. 6 (a). Return to normal posture. The step width W is obtained as the distance from when the distance sensor 28 detects the side surface of the step as shown in FIG. 4A until the edge of the step is detected as shown in FIG. 4C. be able to.

  The operation of the control unit 8 shown in FIG. 1 will be described with reference to FIGS. First, in response to an instruction from the input unit 74, the CPU 72 gives a drive signal to the motor driver 66 via the interface 70 to drive the motors 34 and 36. Accordingly, the drive wheels 6 and 12 start driving, and the mobile robot starts to move in a predetermined direction as shown in step S10. At the start of this movement, the distance sensor unit 28 is similarly operated by the CPU 72 and the detection of the obstacle on the travel path is started. As for the moving distance of the mobile robot, the shaft outputs of the wheel drive motors 34 and 36 are detected by the encoder 62 and input to the CPU 72 via the interface 70 as counter signals. The counter signal is accumulated in the CPU 72 and the moving distance of the mobile robot is stored in a storage device (not shown). In step S12, when a step is detected on the moving path along with the movement by the sensor signal from the distance sensor unit 28 via the interface 70, the approach operation shown in step S13 is started. That is, the mobile robot is further moved toward the step, and a drive signal is given to the motor 38 via the interface 70, and the distance sensor unit 28 is lifted together with the support legs as shown in FIG. 4B. . As the distance sensor unit 28 rises and moves, the CPU 72 calculates the height H of the step from the sensor signal. Here, the CPU 72 determines whether or not the step can be overcome as shown in step S14. When the step is higher than the radius of the drive wheels 6 and 12, it is determined that the mobile robot cannot get over the step. If the step has a height H that can be traversed, or if the height H is not detected due to the complicated shape of the step, an operation for avoiding the step is started as shown in step S15. . In the avoidance operation, with the driven wheels 30 and 32 being lowered by the CPU 72, a difference is given to the rotational drive of the wheel drive motors 34 and 36 so that the drive wheels 6 and 12 are rotated at different rotational speeds. The direction is changed. When the traveling direction is changed, the process returns to step S10 again, and steps S10 to S14 are similarly repeated.

  In step S14, when the CPU 72 determines that the step can be overcome, it is an operation of climbing the step described with reference to FIG. 6C or an operation of descending the step described with reference to FIG. It is determined whether or not there is an operation of descending immediately after going up the step explained with reference to FIG. (Steps S16, S17, S18) After this determination, the respective operations are executed to step through the steps. When the level difference is stepped over, the process returns to step S10 again, and traveling for dealing with the next level difference is continued.

  In the mobile robot shown in FIG. 1, it is preferable that the configuration is symmetrical with respect to the vertical axis passing through the centers of the drive wheels 6 and 12, and is substantially symmetric in the longitudinal direction with respect to the traveling direction. However, when the mobile robot is placed on a flat travel path, its center of gravity is positioned slightly behind the direction of travel relative to the geometric center of the side shape relative to the direction of travel. It is preferable. That is, while the mobile robot is traveling on a flat traveling path, a stable driving force is moved by providing a center of gravity position behind the substantially vertical plane including the axes of the rotating drive wheels 6 and 12 in the traveling direction. Given to the robot, it can reliably step through the steps. In order to arrange the center of gravity position rearward, the mounting position of the control unit 8 on the main body frame 10 may be slightly shifted rearward, or the counterweight may be mounted on the main body frame as necessary. . When stepping over the level difference, the support legs 20 and 22 are raised or lowered to move the position of the center of gravity as follows.

  As shown in FIG. 6 (a), while the mobile robot is traveling on a flat road, the center of gravity of the mobile robot is placed slightly behind the geometrical approximate center of the mobile robot along the traveling direction. Has been. Thereby, the rotational force of the drive wheels 6 and 12 is more reliably transmitted to the travel path. As shown in FIG. 6B, even if the front driven wheel 30 is raised, the robot does not fall down because the center of gravity is behind. This ensures that the rear driven wheel 30 is brought into contact with the travel path. As shown in FIG. 6C, when the driving wheels 6 and 12 come into contact with the step, an external force applied to the driving wheel 6 from the step and pushed back acts on the rear driven wheel 30. As the rear wheel moves rearward, the rear driven wheel 30 is securely brought into close contact with the travel path. Further, as the driving wheels 6 and 12 go up the step, the support leg 22 is lowered and the rear driven wheel 30 is surely pushed down, and the rear driven wheel 30 assists in overcoming the step between the driving wheels 6 and 12. It will be. As already described, in order to prevent the mobile robot from moving backward due to slippage of the driven wheel, the driven wheel is provided with a reverse rotation prevention mechanism such as a gear mechanism or a clutch mechanism that allows rotation in only one direction. Is preferred. By these mechanisms, it is possible to prevent the mobile robot from sliding so as to be returned in the direction opposite to the traveling direction.

  As shown in FIG. 6 (d), when the driving wheel 6 rides on the step, if the position of the center of gravity is similarly located on the rear side, the rear driven wheel 32 pushed down by the support leg 22 is surely secured. The posture of the mobile robot is stabilized by contacting the travel path. While the mobile robot is tilted forward as shown in FIGS. 7E and 7F, the center of gravity moves slightly forward with respect to the approximate geometric center of the mobile robot along the traveling direction. Is done. When the center of gravity moves, the mobile robot is stably supported by the front driven wheel 30 and the driving wheel. When the mobile robot returns to the normal posture as shown in FIG. 7G, the center of gravity is moved slightly behind the geometric center as in FIG. 6A.

  In the above-described embodiment, the driven wheels 30 and 32 are raised or lowered by the support legs 20 and 22, but instead of the support legs 20 and 22, a rack as shown in FIGS. 11A and 11B. The driven wheels 30 and 32 may be raised or lowered by a linear motion mechanism such as an AND pinion mechanism. That is, in the straight path mechanism as shown in FIG. 11, racks 80 and 82 as straight path portions are supported by the main body frame 10 so as to be vertically movable so as to intersect the main body frame 10, and below the racks 80 and 82. The driven wheels 30 and 32 already described are fixed, and the racks 80 and 82 are engaged with pinions 84 and 86 fixed to the main body frame 10. The pinions 84 and 86 are meshed with gears fixed to the motor shafts of the motors 38 and 40.

  In such a straight path mechanism, when the mobile robot is moved on a flat travel path, the rack is arranged so that the main body frame 10 is maintained substantially parallel to the travel path as shown in FIG. The mobile robot is moved in a state where 80 and 82 are extended below the main body frame 10. When the step is detected by the distance sensor unit 28, the motor 38 is driven to rotate the pinion 84 as shown in FIG. 11A, and the rack 80 meshed with the pinion 84 is indicated by the arrow V. The driven wheel 30 is raised to a position higher than the step. When the mobile robot is moved and the drive wheels 6 and 12 ride on the flat road on the level difference, the motor 38 is driven to rotate the pinion 84 in the reverse direction, and the rack 80 meshed with the pinion 84 is lowered to follow the operation. The moving wheel 30 is brought into contact with a flat road on the step. Similarly, when the driven wheel 32 approaches the step, the motor 40 is driven to rotate the pinion 86, the rack 82 meshed with the pinion 86 is raised, and the driven wheel 32 is moved beyond the step as indicated by an arrow V. Raised to a higher position. Thereafter, the driven wheel 32 is lowered and brought into contact with a flat road on the level difference. Thus, also in the linear motion mechanism, the driven wheels 30 and 32 can be lifted or lowered as well as the support legs 20 and 22 to overcome the step. Also in the mobile robot according to this modification, the control unit 8 detects a step by comparing the distance detected by the distance sensor unit 28 with the reference value (observation distance L0), and the vertical movement of the distance sensor unit 28 and the distance sensor are detected. The height H of the step is estimated according to the distance detected by the unit 28, and the width W of the step is estimated according to the distance traveled by the driving wheels 6 and 12 and the distance detected by the distance sensor unit 28. The operation based on this detection is the same as that of the above-described embodiment, and the description thereof is omitted because it is the same as that of the mobile robot according to the embodiment described above.

It is a side view which shows roughly the side mechanism of the mobile robot which concerns on one Example of this invention. It is a rear view which shows roughly the bottom part mechanism under the main body frame of the mobile robot shown in FIG. It is a block diagram which shows the circuit of the control part mounted on the main body frame shown by FIG. (A) to (c) are side views schematically showing the operation of the mobile robot for explaining the sensor operation in the distance sensor unit shown in FIG. It is a graph which shows the change of the detection distance based on the output signal from the distance sensor part shown by FIG. (A)-(d) is a side view which shows roughly the operation | movement which traverses the level | step difference in the mobile robot shown by FIG. (E)-(f) is a side view which shows roughly the operation | movement which traverses the level | step difference in the mobile robot shown by FIG. It is a side view which shows roughly the operation | movement which goes down the level | step difference in the mobile robot shown by FIG. It is a side view which shows roughly the operation | movement over a level | step difference in the mobile robot shown by FIG. It is a flowchart which shows the control action in the control part shown by FIG. It is a side view which shows roughly the modification of the mobile robot shown by FIG.

Explanation of symbols

    4,14. . . Wheel axle 6,12. . . Drive wheels, 8. . . Control unit, 10. . . Main body frame 16, 18. . . Brackets 20, 22. . . Support legs, 28. . . Distance sensor unit 30, 32. . . Driven wheel, 34, 36. . . Wheel drive motor, 38, 40. . . Link drive motor 44, 46. . . Gears, 48, 50. . . Rotating belt, 52, 54. . . Link shaft, 56, 58. . . Motor gears, 60. . . Distance sensor 62, 64. . . Encoder, 66, 68. . . Motor driver, 70. . . Interface, 72. . . CPU, U, 80, 82. . . Rack, 84, 86. . . Pinion

Claims (6)

Body frame,
Driving wheels for moving the main body frame on the road,
A first driven wheel provided forward with respect to the running direction of the main body frame;
A distance sensor unit for detecting a distance in the running direction of the main body frame at a certain depression angle;
A first vertical movement mechanism that vertically moves the first driven wheel and the distance sensor integrally on the body frame while maintaining the depression angle substantially constant;
A control unit that detects a step on a road based on a distance signal from the distance sensor unit and moves the first vertical movement mechanism up and down along with the movement of the main body frame;
A mobile robot characterized by comprising: A second driven wheel provided rearward with respect to the traveling direction of the main body frame;
A second vertical movement mechanism for moving the second driven wheel up and down;
Consisting of
2. The mobile robot according to claim 1, wherein the control unit operates the second vertical movement mechanism together with the movement of the main body frame corresponding to the step detected based on a distance signal from the distance sensor unit. .   The distance sensor unit includes a light source unit that emits a light beam and a photodetector that detects a reflected light beam from the runway, and the control unit measures a distance based on a signal from the photodetector. The mobile robot according to claim 1.     The vertical movement mechanism includes a parallel link mechanism in which the distance sensor unit is provided in a link part that is moved up and down, or a linear movement mechanism in which the distance sensor part is provided in a linear movement part that is moved up and down. The mobile robot according to claim 1.     The mobile robot according to claim 1, wherein the driven wheel includes a reverse rotation prevention mechanism that allows rotation along the road direction and prevents rotation opposite to rotation in the road direction. .     The control unit detects a step by comparing the distance detected by the distance sensor unit with a reference value, and the height of the step according to the vertical movement of the distance sensor unit and the distance detected by the distance sensor unit. 2. The mobile robot according to claim 1, wherein the step width is estimated according to a travel distance by the drive wheel and a distance detected by the distance sensor unit.

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