JP4766381B2 - Leg wheel type mobile robot, its operation method and program - Google Patents

Description

  The present invention relates to a leg-wheel type mobile robot having a plurality of legs for walking and having a wheel that can run on a grounding surface attached to the tip of the leg, an operation method thereof, and a program.

  In the future, demand for service robots for daily life, medical welfare, and public sector is expected to increase. Movement is one of the important functions for robots that work with humans, and leg-wheel type mobile robots having a configuration that can move efficiently and at high speed in factories and the like have been developed.

A leg-wheel type mobile robot travels on a flat ground with a wheel attached to the tip of the leg in a stable posture, and in places where there are obstacles such as steps or grooves such as stairs, for example, three legs are rotated and expanded and contracted. Then walk like crutches and cross obstacles.
That is, efficient and high-speed movement is possible by performing an operation that combines wheel running and leg walking.
Such a leg-wheel type mobile robot is disclosed in Patent Document 1, for example.

As shown in FIG. 5, the leg-wheel type mobile robot of Patent Document 1 includes a main body 31, a central leg 33 that is connected to a lower portion of the main body 31, can be expanded and contracted, and can be rotated with respect to the main body 31 around a horizontal axis. And side legs 35 that are connected to the left and right sides of the main body 31 and can be expanded and contracted and can rotate about the horizontal axis with respect to the main body 31.
Wheels 37 that can travel on the ground contact surface are attached to the lower ends of the center leg 33 and the side legs 35.

  6A and 6B show the traveling operation of the leg-wheel type mobile robot. FIG. 6A is a front view and FIG. 6B is a side view. As shown in FIG. 6 (B), the center leg 33 and the side leg 35 are greatly opened relative to each other and the wheel 37 of the center leg 33 and the side leg 35 is driven to drive on the ground surface. be able to.

  On the other hand, FIG. 7 shows the walking motion of the leg-wheel type mobile robot. As shown in FIG. 7, it is possible to walk from the state (1) to the state (8) and step through the stairs by combining the rotation of the central leg 33 and the side leg 35 and the expansion / contraction operation.

The expansion and contraction and rotation of the central leg 33 and the side legs 35 during walking in this way are driven by drive motors (for example, servo motors) corresponding to the respective operations, and the drive motors are controlled as follows. Yes.
The difference between the momentary command position of the drive motor according to the operation program or the like and the position feedback as the current position read from the position detector attached to the drive motor is taken as a position deviation. A speed command obtained by multiplying the position deviation by the position loop gain is output.
The difference between this speed command and the speed feedback obtained from the current position read from the position detector is taken as a speed deviation, and a current command is output based on this speed deviation.
Further, the motor current is output to the drive motor based on the difference between the current command and the detected current feedback as the actual current flowing through the drive motor.
By performing such position feedback control, the operation shown in FIG. 7 is performed.

  Generally, in position feedback control, the greater the position loop gain value, the higher the rigidity of the drive shaft, so the followability of the drive shaft with respect to the position command is improved. The load applied to the speed reducer connected between the leg 33 and the side leg 35 is increased.

By the way, the control of the plurality of drive motors is often performed in cooperation with each other. That is, when the operation of a certain drive motor is delayed, the operation of another drive motor is corrected and driven in accordance with this delay. This prevents an excessive force from acting on each part of the robot due to an operation delay of a certain drive motor.
Japanese Patent Laid-Open No. 2003-205480 “Leg Wheel Mobile Robot”

However, if the control of each drive motor is performed in cooperation with each other in this way, the control becomes complicated. Therefore, it is possible to simplify the control by performing position feedback control (hereinafter referred to as local position feedback control) that is separately controlled without cooperation between the drive motors.
Further, when the central leg 33 and the side leg 35 are in contact with the ground, the central leg 33 and the side leg 35 are held on the floor by its own weight or static frictional force, and the walking system is like a closed chain mechanism. It has become.
Therefore, if the posture of the robot is changed while the central leg 33 and the side leg 35 are both in contact with the ground, if a large positional deviation or speed deviation occurs as the operation becomes dynamic, a large torque is applied to the drive motor or the like. This will generate excessive stress inside the robot.
If the stress generated in the robot becomes larger than the static frictional force between the leg and the grounding surface, the leg is displaced on the grounding surface or the robot jumps up. As a result, the position of the robot cannot be determined and control becomes difficult.
In particular, this problem becomes significant unless the driving motors are linked.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a leg-wheel mobile robot capable of performing posture change operation by local position feedback control with high gain without generating excessive stress inside the robot, and an operation method and program thereof. It is in.

In order to achieve the above object, according to the present invention, a main body, a plurality of legs that are rotatably connected to the main body and that can be expanded and contracted or bent, and a rotation operation and expansion or contraction or bending for each of the plurality of legs. A plurality of drive motors that perform the operation, and a control device that controls the plurality of drive motors to cause the plurality of legs to walk, and each leg is attached to the tip of the leg so as to contact the grounding surface A leg wheel type mobile robot having a wheel that rotates on the ground contact surface and a braking device that brakes rotation of the wheel,
The control device is in a state where the plurality of legs are grounded, and when the posture of the main body is changed by controlling the drive motor, at least one of the braking devices of the plurality of legs is deactivated, There is provided a leg-wheel mobile robot characterized in that stress accumulated inside the robot is released to the outside due to a change in posture of the main body from the leg that is capable of rotational movement.

In order to achieve the above object, according to the present invention, a main body, a plurality of legs that are rotatably connected to the main body and that can be expanded and contracted or bent, and a rotation operation and expansion and contraction with respect to each of the plurality of legs. Or a plurality of drive motors for performing a bending operation, each leg being attached to the tip of the leg so as to contact the grounding surface and rotating on the grounding surface, and braking for braking the rotation of the wheel An operation method of a leg-wheel mobile robot having a device,
When the plurality of legs are in a grounded state and the posture of the main body is changed by the drive motor, the braking device of at least one of the plurality of legs is deactivated, and the wheel is allowed to rotate. There is provided an operation method of a leg-wheel type mobile robot characterized in that stress accumulated in the robot is released to the outside from the leg due to a posture change of the main body.

Furthermore, in order to achieve the above object, according to the present invention, a main body, a plurality of legs that are rotatably connected to the main body and that can be expanded and contracted or bent, and a rotation operation and expansion and contraction with respect to each of the plurality of legs. Or a plurality of drive motors for performing a bending operation, each leg being attached to the tip of the leg so as to contact the grounding surface and rotating on the grounding surface, and braking for braking the rotation of the wheel An operation program for a leg-wheel mobile robot having a device,
When the plurality of legs are in a grounded state and the posture of the main body is changed by the drive motor, the braking device of at least one of the plurality of legs is deactivated, and the wheel is allowed to rotate. An operation program for a leg-wheel mobile robot is provided, which causes a computer incorporated in the leg-wheel mobile robot to execute processing for releasing stress accumulated in the robot from the leg to the outside due to the posture change of the main body. Is done.

In this way, when changing the posture of the main body, at least one of the wheels of the plurality of legs can be rotated on the ground surface, and from there, the stress accumulated in the robot due to the posture change of the main body is released to the outside Therefore, even if an excessive torque is generated in the drive motor when the posture of the main body is changed by the high gain local position feedback control, the torque is automatically released to the outside by moving the wheel.
Therefore, the posture changing operation by the high gain local position feedback control can be performed without generating excessive stress inside the robot.
If the operation of changing the posture of the main body while grounding a plurality of legs is performed by high gain local position feedback control, an excessive torque is likely to be applied to the drive motor that rotates or expands and contracts the legs.
However, according to the present invention, at this time, at least one of the braking devices of the plurality of legs is deactivated, so that an excessive torque is prevented from being generated in the drive motor.

  According to a preferred embodiment of the present invention, in the leg-wheel mobile robot, the central axes when the plurality of legs are rotationally driven by the corresponding drive motors are horizontal axes that are in parallel with each other. Each of the central axes when the plurality of leg wheels rotate is a rotation axis that is in a parallel relationship with the horizontal axis.

In this way, the plurality of legs are each driven to rotate around a horizontal axis parallel to each other, and the wheels of the plurality of legs can rotate around an axis parallel to the horizontal axis. When an excessive torque is applied to the rotation drive motor, the wheels of the other legs that have deactivated the braking device rotate and move more smoothly.
Therefore, even when the posture of the main body is changed by high-gain local position feedback control, it is possible to more reliably prevent an excessive torque from being generated in the drive motor.

According to a preferred embodiment of the present invention, in the leg wheel type mobile robot, the control device deactivates at least one of the braking devices of the plurality of legs because the plurality of legs perform a walking motion. While you are .

In this way, the control device deactivates at least one of the braking devices of the plurality of legs when changing the posture of the main body while grounding the plurality of legs during the walking operation. When the torque of the drive motor is excessive, the wheel is released from the movable wheel.
Therefore, walking by high gain local position feedback control can be performed stably.

  According to a preferred embodiment of the present invention, in the above-described leg-wheel type mobile robot, when the control device changes the posture of the main body while grounding the plurality of legs, the brake device is inactivated. Legs other than those that need to maintain distance from obstacles.

  As described above, when the control device changes the posture of the front main body while grounding a plurality of legs, it is necessary to perform control for maintaining the distance from an external obstacle to deactivate the braking device. Leg brakes that need to maintain distance from obstacles such as steps and grooves are activated, and the wheels that have deactivated the brakes to release excessive torque Even if the robot moves, the robot is prevented from colliding with an obstacle.

As described above, according to the present invention, in a leg-wheel type mobile robot, when the posture of the robot body is changed, at least one of the braking devices of the plurality of legs is deactivated, and the wheels of the legs are set against the ground plane. Therefore, if an excessive torque is applied to the drive motor, the wheel can be released from the movable wheel.
Therefore, the posture changing operation by the high gain local position feedback control can be performed without generating excessive stress inside the robot.

  A preferred embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

  FIG. 1 shows an overall configuration of a leg-wheel type mobile robot according to an embodiment of the present invention. FIG. 2 is a side view when the leg-wheel type mobile robot is walking. As shown in FIGS. 1 and 2, the leg-wheel mobile robot 10 includes a main body 1 that is a central body part, a central leg 3 that is connected to the main body 1 and is rotated around a horizontal axis in a vertical plane, and left and right A tripod structure including a pair of side legs 5.

The central leg 3 is pivotally moved in a vertical plane with respect to the main body 1 and is connected to the main body 1 so as to be expanded and contracted or bent. A wheel 9 that slides above and a brake that brakes the rotation of the wheel 9 are provided.
The rotation operation and expansion / contraction or bending operation of the central leg 3 with respect to the main body 1 are performed by a drive motor (for example, a servo motor) incorporated in the main body 1 or the central leg 3.
Further, two joints 7 that can rotate around a horizontal axis are provided at the center leg tip.

The side legs 5 are rotated in a vertical plane with respect to the main body 1 and connected to the main body 1 so as to be expanded and contracted or bent. And a brake that brakes the rotation of the wheel 9.
The rotation operation and expansion / contraction or bending operation of the side legs 5 with respect to the main body 1 are performed by a drive motor (for example, a servo motor) incorporated in the main body 1 or the side legs 5. The left and right side legs 5 are rotated in synchronization with each other.
In addition, one joint 11 that can rotate around a horizontal axis is provided at the tip of each of the left and right side legs.

  FIG. 3A is a side view showing the configuration of the wheel 9 and its drive motor 12 provided at the lower end of each of the central leg 3 and the side leg 5. FIG. 3B is a view taken in the direction of arrows AA in FIG. As shown in FIG. 3B, wheels 9 are provided at the front and rear of each leg.

In FIG. 3, the rotational driving force of the wheel drive motor 12 is transmitted to the drive shaft 17 via the bevel gear 15, and the rotation of the drive shaft 17 is transmitted to the wheel shaft 21 by the transmission belt 19 to drive the wheel 9. The
Further, as shown in FIG. 3A, brakes 23 that brake the rotation of the drive shaft 17 and stop the rotation of the wheels 9 are provided at the lower end portions of the legs.

In addition, the main body 1 is provided with a control device that controls each operation of the leg-wheel mobile robot 10 such as running on the ground surface, walking, and posture change.
That is, the control device controls the operation of the drive motor that rotates and expands and contracts each of the central leg 3 and the side legs 5 and the drive motor 12 for the wheels of each leg. Note that the control device can receive, for example, an instruction from an operator wirelessly and can control each operation of the robot according to the instruction. The control device can also control each operation of the robot according to a program stored in the control device in advance.

The leg-wheel type mobile robot 10 having the above-described configuration can travel on the ground contact surface with the wheel 9 at the tip of the leg. For example, stable running is possible by driving the wheels 9 of the central leg 3 and the left and right side legs 5 while the central leg 3 and the left and right side legs 5 are opened widely. In this example, no steering mechanism is provided, but turning is possible by giving a speed difference to each wheel 9.
On the other hand, the movement of the left and right side legs 5 is synchronized, and the walking action is performed by alternately swinging the center leg 3 and the left and right side legs 5 alternately as standing legs and free legs. The standing leg means that the leg is grounded, and the free leg means that the leg is separated from the grounding surface.

FIG. 4 is a diagram illustrating the timing at which the brake 23 is deactivated when the leg-wheel type mobile robot 10 steps through the stairs. The control device controls the rotation and expansion / contraction of the central leg 3 and the side legs 5 so that the walking motion as shown in FIG. 4 is performed.
In FIG. 4, the posture is changed so as to move the center of gravity forward from the state (1) to the state (2), and the side legs 5 are separated from the ground contact surface and passed through the state (3) as in the state (4). Land the side legs 5. Subsequently, the posture is changed so as to move the center of gravity forward again to the state (5).
In this way, the operation of stepping through the stairs is performed. When the posture is changed from the state (1) to the state (2) or from the state (4) to the state (5), the central leg 3 and the side legs 5 Since both legs are grounded, the robot is like a closed chain mechanism.

Therefore, when this posture change is performed by local position feedback control with high gain, excessive torque tends to act on the drive motor and the joints 7 and 11.
Therefore, according to the embodiment of the present invention, when the posture of the main body 1 is changed by high-gain local position feedback control in a state where both the central leg 3 and the side leg 5 are grounded, the central leg 3 and the side legs Any one of the brakes 5 is deactivated so as to be movable in the traveling direction.
For example, when the posture is changed from the state (1) to the state (2), the brakes 23 of the wheels 9 of the side legs 5 are deactivated and the side legs 5 are allowed to rotate. Similarly, when changing the posture from the state (4) to the state (5), the brake 23 of the side leg 5 is kept inactive.

  As a result, when the posture is changed from the state (1) to the state (2) or from the state (4) to the state (5), excessive torque is applied to the drive motor or the like when high gain local position feedback control is performed. If it tries to do so, the non-braking wheel 9 will automatically rotate and release the torque.

In particular, according to the present embodiment, the central leg 3 and the side leg 5 are respectively driven to rotate around horizontal axes parallel to each other, and the wheel 9 of the central leg 3 or the side leg 5 with the brake 23 inactivated is It is configured to be rotatable around an axis parallel to the horizontal axis.
With this configuration, when the posture is changed from the state (1) to the state (2) or from the state (4) to the state (5) in FIG. If excessive torque is to be applied, the wheels 9 of the other legs that have deactivated the brake 23 rotate smoothly, so that this torque can be reliably released.

The above-described operation of the leg-wheel type mobile robot 10 is performed by the control device, but can be executed by a computer incorporated in the robot 10.
That is, the computer includes the control device and a storage device that stores an operation program for performing the above-described operation, and executes processing for the above-described operation according to the operation program.

As described above, according to the embodiment of the present invention, when the posture of the robot is changed while the center leg and the side leg are grounded in the leg-wheel type mobile robot, the brake of at least one of the center leg and the pair of side legs is used. The wheel of this leg can be moved with respect to the ground plane, so that if a large torque is applied to the drive motor or joint, the brake-inactivated wheel will automatically move to release the torque. Is done.
Accordingly, even when the posture of the main body is changed by rotating or extending or retracting the leg by high gain local position feedback control, it is possible to prevent excessive torque from being generated, and stable high speed operation is possible. Become.

In addition, when the control device changes the posture of the main body while grounding the center leg and the side legs, the brakes are deactivated on the legs other than the legs that need to maintain the distance from external obstacles. is there.
In this way, the brakes are deactivated by the legs that do not require control to maintain the distance to external obstacles, so it is necessary to maintain the distance from obstacles such as steps and grooves. A brake on a leg is activated, preventing the robot from colliding with an obstacle.

In the above description, when walking the staircase, when changing the posture of the main body with both the central leg and the side leg in contact with the ground, the brake of either leg is deactivated. It is not limited to. For example, when the robot changes its posture to perform a predetermined work, particularly when changing the posture with the central leg and the side legs in contact with the ground, at least one of the brakes of the plurality of legs is deactivated. The large torque generated in the drive motor or the like can be released.
Further, in the above description, the case is a leg-wheel type mobile robot that performs three-legged walking, but the present invention is not limited to this, and the present invention is also applicable to a leg-wheel type mobile robot that performs two-legged walking or walking with four or more legs. Is possible.
Further, in the above description, the wheel provided with the leg is driven by the motor, but the wheel may be attached to the tip of the leg without providing the wheel driving device.
The above-described brake 23 constitutes a braking device that brakes the rotation of the wheel 9, but the braking device is constituted by an actuator such as a motor whose output shaft is coaxially connected to the rotating shaft of the wheel or other suitable device. May be.
Thus, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

It is a front view of the leg wheel type mobile robot by the embodiment of the present invention. It is a side view of the leg wheel type mobile robot by the embodiment of the present invention. It is a figure which shows the wheel provided in the leg tip, and its drive mechanism. It is a figure which shows the timing which deactivates the brake of the wheel by embodiment of this invention. It is a front view which shows the conventional leg wheel type mobile robot. It is a figure which shows wheel driving | running | working of the conventional leg wheel type mobile robot. It is a figure which shows the walk operation | movement of the conventional leg wheel type mobile robot.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main body 3 Center leg 5 Side leg 7, 11 Joint 9 Wheel 10 Leg wheel type mobile robot 12 Wheel drive motor 15 Bevel gear 17 Drive shaft 19 Transmission belt 21 Wheel shaft
23 Brake

Claims (6)

A main body, a plurality of legs that are rotatably connected to the main body, and that can be expanded and contracted or bent; a plurality of drive motors that perform a rotation operation and an expansion or contraction or bending operation on each of the plurality of legs; A control device for controlling the driving motor of the plurality of legs to cause the plurality of legs to walk, wherein each leg is attached to a tip of the leg so as to contact the grounding surface, and a wheel that rotates on the grounding surface; A leg wheel type mobile robot having a braking device for braking rotation of a wheel,
The control device is in a state where the plurality of legs are grounded, and when the posture of the main body is changed by controlling the drive motor, at least one of the braking devices of the plurality of legs is deactivated, A leg-wheel mobile robot characterized in that the stress accumulated in the robot is released to the outside due to the posture change of the main body from the leg that can be rotated and moved. The central axes when the plurality of legs are rotationally driven by the corresponding drive motors are horizontal axes that are parallel to each other,
2. The leg-wheel type mobile robot according to claim 1, wherein each central axis when the plurality of leg wheels rotates is a rotation axis that is parallel to the horizontal axis. 3. Leg according to claim 1 wherein the controller for deactivating at least one of the braking device of the plurality of legs is between the plurality of legs is performing walking, characterized in that Wheel mobile robot. When the control device changes the posture of the main body while grounding the plurality of legs, the brake device is deactivated by a leg other than the leg that needs to maintain a distance from an external obstacle. there, leg-wheeled mobile robot according to any one of claims 1 to 3, characterized in that. A main body, a plurality of legs that are rotatably connected to the main body and that can be expanded and contracted or bent, and a plurality of drive motors that perform a rotation operation and an expansion or contraction or bending operation on each of the plurality of legs. Each leg is a method of operating a leg-wheel type mobile robot having a wheel attached to the tip of the leg so as to be in contact with the grounding surface and rotating on the grounding surface, and a braking device for braking the rotation of the wheel. There,
When the plurality of legs are in a grounded state and the posture of the main body is changed by the drive motor, the braking device of at least one of the plurality of legs is deactivated, and the wheel is allowed to rotate. A method for operating a leg-wheel type mobile robot, characterized in that stress accumulated in the robot is released to the outside by a posture change of the main body from the leg. A main body, a plurality of legs that are rotatably connected to the main body and that can be expanded and contracted or bent, and a plurality of drive motors that perform a rotation operation and an expansion or contraction or bending operation on each of the plurality of legs. Each of the legs is an operation program for a leg wheel type mobile robot having a wheel attached to the tip of the leg so as to be in contact with the contact surface and rotating on the contact surface and a braking device for braking the rotation of the wheel. There,
When the plurality of legs are in a grounded state and the posture of the main body is changed by the drive motor, the braking device of at least one of the plurality of legs is deactivated, and the wheel is allowed to rotate. An operation program for a leg-wheel type mobile robot, characterized by causing a computer incorporated in the leg-wheel type mobile robot to execute processing for releasing stress accumulated inside the robot to the outside from a leg by a posture change of the main body.

Images