JPH0436834B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides dynamic self-reliance (i.e., the center of gravity is outside the sole) of a bipedal walking robot having multi-jointed two legs with soles. This invention relates to a control method for stable walking.

[Background of the invention]

In order for a bipedal walking robot as described above to walk independently, all necessary functional devices must be mounted on the robot body, but in the case of a multi-jointed bipedal walking robot with these devices mounted on the head, the center of gravity must be exists at the top, making it unstable. Furthermore, in order to make a multi-jointed bipedal walking robot walk at high speed, a dynamic walking method in which the center of gravity moves outward from the sole surface of the foot is used, so there is a high possibility that it will become unstable due to the effects of external disturbances and internal disturbances. For example, in multi-jointed bipedal walking robots that are equipped with all the necessary functional devices, hydraulic drive mechanisms are often used for the joints because large torques are applied to the joints. Changes occur in joint motion, which act as internal disturbances. In addition, the floor or ground (generally referred to simply as the ground) on which the user walks is uneven, and shocks and the like act as disturbances.

The journal of the Robotics Society of Japan, Vol. 1, No. 3 (October 1983) describes the control of the period for replacing the legs that support the center of gravity in multi-jointed bipedal walking robots.
``Analysis and control of constrained bipedal locomotion'' by Masami Ito and Tatsuo Narukiyo in pp.31-35.
This paper states that in dynamic stability control of bipedal walking robots, it is important to control the period during which support legs are replaced. No consideration has been given to solutions for instability caused by internal disturbances due to changes in dynamic characteristics resulting from changes in

In addition, as a literature on the control of bipedal walking robots with soles, there is ``On the control and realization of high-speed bipedal walking robots'' by Tsutomu Mita in Robot Engineering (September 1982), pp. 104-114. . This paper discusses control of the sole of the foot, but it discusses control to make the sole of the foot in the air horizontal to the ground and control of the posture of the supporting leg, which is similar to the above-mentioned literature. No active measures to address stability factors are mentioned.

[Purpose of the invention]

The purpose of the present invention is to reduce disturbances and internal disturbances by using signals from ground information sensors installed on the soles of the feet in dynamic walking control, which is essential for speeding up the walking of articulated bipedal walking robots with soles. To provide a walking stability control method for a multi-joint bipedal walking robot with soles, which performs stable control by eliminating the influence and enables stable independent walking of the multi-joint bipedal walking robot with soles.

[Structure of the invention]

In the walking stability control method of the multi-jointed bipedal walking robot with soles of the present invention, each leg has a hip joint, a knee joint, an ankle joint, and a sole connected via the ankle joint, and each of the above joints The joint angle around the pitch axis can be controlled, and the joint angle around the roll axis of the waist joint and ankle joint can also be controlled, and the pitch axis of each of the above joints can be controlled at any time based on a preset walking pattern In the walking control method for a multi-jointed bipedal walking robot with soles, which realizes walking by sequentially controlling the joint angles of the above-mentioned joints about the pitch axis in response to joint angle command signals, is equipped with a sole contact information sensor that detects the contact status between the sole of the foot and the ground. A control means for locking the joint angles of the hip joint, knee joint, and ankle joint around the pitch axis based on a set walking pattern, and controlling the joint angles of the hip joint and the ankle joint around the roll axis during the locking period as described above. The present invention is characterized by comprising a control means for correcting a horizontally tilted contact of the sole of the foot with the ground.

[Embodiments of the invention]

Examples of the present invention will be described below.

FIG. 2 shows a front view of the articulated bipedal walking robot device with soles according to this embodiment. This walking robot device has a total of 12 degrees of freedom for both legs. In other words, the hip joint located at the position corresponding to the human lower back has a waist pitch axis 1 and the waist roll axis 2, and the knee joint located at the position equivalent to the knee has a knee pitch axis 3, and the knee joint located at the position corresponding to the ankle. The ankle joint has an ankle pitch axis 4 and an ankle roll axis 5, and the joint provided on the thigh for changing direction has a direction changing yaw axis 6. Each joint shaft has a hydraulic swing actuator 10 for driving the joint, a potentiometer 12 for joint angle detection, and a servo valve 13 for controlling the operation of the hydraulic swing actuator 10 on the shaft of the hydraulic swing actuator 10. is installed.

This robot has soles connected to both legs by ankle joints, and the soles of the feet are designed to compensate for instability during dynamic walking to a certain extent, and also to compensate for instability during dynamic walking. Start walking,
It also plays an important role in realizing work such as finishing walking and stopping. As shown in FIG. 3, a total of eight ground contact information sensors 11, four on each foot, are installed on the sole surface of the foot.

The hydraulic power source is composed of a hydraulic pump motor 9, a hydraulic tank 9', a relief valve 9'', etc., and provides the pressure and oil flow rate necessary to drive the above-mentioned articulated bipedal traveling robot device with soles. supply
The flow rate of oil to the hydraulic swing actuator 10 of each joint is adjusted by moving the servo valve 13.
Thereby, the drive of the hydraulic swing actuator 10 is controlled.

A control unit 7 is installed above the hydraulic power source with a heat insulating material 8 interposed therebetween to prevent it from being affected by the heat generated by the hydraulic pump motor 9. The control unit 7 is composed of a microcomputer that processes information that determines the walking motion of the robot, its peripheral equipment, and a servo amplifier that drives and controls a servo valve 13 that controls the flow rate of oil using an electric current.

Between the hydraulic power source 9, 9', 9'' and the servo valve 13,
Connected with a flexible plumbing hose. Further, the control unit 7, the ground information sensor 11, the servo valve 13, and the angle detection potentiometer 12 are connected by a signal cable.

FIG. 1 shows an overall diagram of the control system of the articulated bipedal walking robot device with soles of this embodiment. A joint angle command signal according to the walking pattern output from the computer control system 15 is amplified by the servo amplifier 16 and transmitted to the servo valve 13. The servo valve 13 adjusts the flow rate of oil supplied from the hydraulic sources 9, 9', 9'' by moving the spool inside the valve according to the angle command signal from the servo amplifier 16. The drive of the hydraulic swing actuator 10 is controlled.At the same time, the potentiometer 1 detects the actual joint angle.
The position (angle) feedback control for the joint angle command signal is performed by the signal from 2, and walking is performed according to the walking pattern. On the other hand, a signal from the sole contact information sensor 11 causes control operations to be switched as described below.

FIG. 4 shows the configuration of the control device (computer control system 15 and servo amplifier 16 in FIG. 2). The control device has the illustrated boards arranged on both sides via an internal bus 23. The control device includes a servo amplifier 16a for the right leg, a servo amplifier 16b for the left leg, a microcomputer 17, interface boards 18a and 18b, and a memory board 1.
9, D/A converter 21, A/D converter 2
Consists of 2.

The microcomputer 17 is a memory board 1
The angle commands for each joint required for normal walking are calculated using the built-in programs and walking patterns in the D/A converter 21 .

FIG. 5 shows a conceptual diagram of walking pattern data.
The walking pattern data represents the movement trajectory that each joint of the multi-jointed bipedal walking robot device with soles should take when walking, and specifically, the walking pattern data as shown in Figure 9. This is joint angle command data extracted discretely from the time series of joint angle commands corresponding to .

The microcomputer 17 extracts joint angle command data to be outputted to each joint next from this walking pattern data, and interpolates between the current joint angle command data and the retrieved data. The angle command resulting from this interpolation is converted and calculated so that it can be output to the D/A converter 21.
Output to A converter 21. The D/A converter 21 converts this angle command into a current, and the servo amplifiers 16a and 16b amplify this current and output it to the servo valve. Further, a response angle signal corresponding to the actual movement of the joint is input from the angle detection potentiometer 12 to the servo amplifiers 16a and 16b via the connector, thereby forming a position feedback type control circuit. FIG. 6 shows a block diagram of the position feedback control circuit.

A flowchart of walking control based on the normal walking pattern described above is shown in FIG.

The drive signal switching circuit 26 in FIG.
ON/OFF of the drive prohibition signal output from
The function is to switch the angle command. The switching status of the angle command signal is as shown in FIG. 8, and when the drive prohibition signal is OFF, the angle command output from the drive signal switching circuit 26 is the same as the angle command output from the microcomputer 17. When the drive prohibition signal turns ON, the angle command output from the drive signal switching circuit 26 is held at the actual angle value at that time, and therefore, regardless of the angle command from the microcomputer 17, that joint is set to the current value. Locked to the angle.

FIG. 9 shows the walking state of the multi-jointed bipedal walking robot device with soles of this embodiment,
A and A' are single-leg support periods, and B is a double-leg support period, which is a support leg switching period in which the leg supporting the center of gravity is replaced.In the present invention, dynamic walking is performed only during this support leg switching period B. Therefore, walking becomes extremely unstable during the period of switching support legs. Joint motion trajectories that enable stable walking are stored in memory in the form of gait patterns, but there is a problem that cannot be solved by simply following these trajectories during the support leg switching period. Examples include adaptation to uneven terrain, changes in dynamic characteristics due to changes in oil temperature, and impact upon touchdown. In order to deal with these problems, this embodiment employs a control method that actively adapts joint movement trajectories to the walking situation using signals from the ground contact information sensor on the sole of the foot during support leg replacement period B. . This will be explained below.

Changes in ground contact information during the target motion during the support leg switching period are shown in FIGS. 10a to 10e. Walking is performed in the direction of the arrow in the figure, that is, in the direction from a to e in the figure. In the figure, black circles represent ground information sensors that are in contact with the ground and are outputting ground information ON signals, and white circles represent ground information sensors that are not in contact with the ground and are outputting ground information OFF signals.

Walking control for the articulated bipedal running robot device with soles of this embodiment to operate as shown in FIG. 10 during the support leg replacement period is performed as follows, as shown in the flowchart of FIG. 11. .

First, the walking pattern is output until the condition a in Fig. 10 is reached, and then the gait pattern is output around the hip pitch axis of the front leg in the direction of the arrow in Fig. 12 a until the ground contact information sensor of the front heel turns ON. Slowly move each joint around the hip pitch axis and ankle pitch axis by the same angle. When one of the ground contact information sensors of the forefoot heel turns ON, the above-mentioned movement prohibition signal is immediately input to all joints around the pitch axis, and all joints around the pitch axis are locked. Next, set the ground contact information sensor of the OFF side of the heel of the front foot to turn ON, that is, the ground contact information sensor of both the heel of the front foot, as shown in Figure 12b, around the roll axes of the ankles and hips of both legs. to control the hydraulic swing actuator. When the state shown in Fig. 10b is reached, in which both the ground contact information sensors of the heels of the front feet are turned ON, all joints around the roll axis are locked, and the joints around the pitch axis are unlocked.

Next, the center of gravity is moved as shown in FIG. 12c from the state shown in FIG. 10b to the state shown in FIG. 10c. For this purpose, control is performed using only the joint data around the pitch axis of the preset walking pattern. At this time, adjust the ankle pitch joint and hip pitch joint of the hind legs by moving them by the same angle so that the soles of the hind legs do not lift off the ground. The sole of the leg is in horizontal contact with the ground, and all ground information sensors on the heel and toes are ON (state shown in Figure 10c).
Continue the above movements until

Next, the walking pattern is controlled from this state to the state shown in Figure 10 d (the heel of the hind foot is raised), but at this time, the toes of the hind foot have left the ground before the center of gravity moves to the front foot. Control the ankle and pitch joints of the legs and feet so that they do not move. When the robot moves to a position in which the center of gravity has been completely moved (the state shown in FIG. 10e), the joints around the roll axis are unlocked and the control method using the normal walking pattern is resumed.

As a result of the above, we have solved the instability of walking due to the influence of uneven ground and changes in dynamic characteristics due to changes in oil temperature, which could not be addressed by control based on walking patterns alone, and achieved stable control during the support leg switching period. obtain.

〔Effect of the invention〕

According to the present invention, by correcting the horizontally tilted contact of the sole of the foot using the signal from the sole contact information sensor, it is possible to compensate for the effects of internal disturbances and external disturbances, achieve stable dynamic walking, and The independent walking performance of the multi-jointed bipedal walking robot can be greatly improved, and the control system requires fewer components.
Since the number of calculation processing steps is small, there is less possibility of erroneous processing or malfunction due to control complexity.

[Brief explanation of drawings]

FIG. 1 is an overall view of the control system of a multi-jointed bipedal walking robot with soles according to an embodiment of the present invention, FIG. 2 is a front view of the bipedal walking robot, and FIG. 3 is a sole view of the bipedal walking robot. 4 is a schematic diagram of the configuration of the control device of the same embodiment, FIG. 5 is a diagram showing joint angle commands based on walking patterns, and FIG. 6 is a block diagram of the joint angle position feedback control circuit. Figure 7 is a flowchart of walking control based on a normal walking pattern, and Figures 8a, b, and c show angle commands from the microcomputer, angle commands output from the drive signal switching circuit, and drive prohibition signals in the above embodiment. FIG. 9 is a diagram showing the state of walking according to the walking pattern, FIG. FIGS. 12A, 12B, and 12C, a flowchart of walking control during the leg switching period, are schematic side and front views showing the joint control mode during the supporting leg switching period. 1...Waist pitch axis, 2...Waist roll axis, 3...
Knee pitch axis, 4...Ankle pitch axis, 5...Ankle roll axis, 6...Direction change yaw axis, 7...Control unit, 8...Insulation material, 9...Hydraulic pump motor,
10...Hydraulic swing rotary actuator, 1
1... Ground information sensor, 12... Potentiometer, 13... Servo valve, 14... Power supply unit,
15... Computer control system, 16... Servo amplifier, 17... Microcomputer, 1
8...Interface board, 19...Memory board, 21...D/A converter, 22...A/
D converter, 23...Internal bus, 24...Amplifier, 25...Limit circuit, 26...Drive signal switching circuit, A, A'...Single leg support period, B...Support leg switching period.

Claims (1)

[Claims] 1. Each leg has a hip joint, a knee joint, an ankle joint, and a sole connected through the ankle joint, and each of the above joints has a joint angle around the pitch axis that can be controlled. The joint angle around the roll axis can also be controlled, and the joint angle around the pitch axis of each of the above joints can be controlled in response to the joint angle command signal around the pitch axis of each of the above joints at any time based on a preset walking pattern. In the gait control method of a multi-jointed bipedal walking robot with foot soles, which realizes walking by sequentially controlling the When the foot ground information sensor detects that the sole of the foot touches the ground with an inclination in the left-right direction, the pitch axis of the hip joint, knee joint, and ankle joint is adjusted based on the preset walking pattern. A control means for locking the joint angles around the roll axis, and a control means for controlling the joint angles of the hip joint and the ankle joint about the roll axis during the locking period so as to correct the above-mentioned horizontally inclined ground contact of the sole of the foot. A walking stability control method for a multi-jointed biped walking robot with soles.