JPH04122585A - Walk control device for leg type mobile robot - Google Patents

Abstract

PURPOSE:To enable the optional change of a walking posture during walking at need by presetting the time series target value on the walking parameter including at least a center-of-gravity position, and determining the reference position from the set center-of-gravity position so as to compute the attitude angle of a robot, thus determining the joint driving control value. CONSTITUTION:The parameter for the center-of-gravity position or the like in the broader term than the joint angle is set as a walking pattern. On the basis of this, the attitude angle of a robot 1 is determined to compute the joint angle, and then the control value is determined. The joint angle is thus determined at real time during walking without setting it previously. As a result, the walking posture can be changed optionally during walking as occasion demands.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a walking control device for a legged mobile robot (1), and more specifically to a legged mobile robot that walks independently based on a preset walking pattern. The present invention relates to a walking control device for a legged mobile robot that can arbitrarily change the gait such as the stride length during walking.

(Problems to be Solved by the Prior Art and Inventions) Japanese Patent Laid-Open No. 62
-97006 is known. In order for such a mobile robot to walk at high speed, joint angles and link angles corresponding to the target center of gravity position and leg position are required, but in this conventional technology, joint angles that are set offline in advance are not used. The information is stored in the memory of the on-board microcomputer, and the joints are controlled based on this information to allow the robot to walk.

Therefore, in this conventional example, the mobile robot had no choice but to walk based on a preset gait, and was unable to change its gait in real time, ie, the road, direction of travel, stride length, speed, etc., in the middle of walking. . In addition, as for the conventional technology of legged mobile robots, there are other publications such as “Journal of Robotics Society of Japan,
A stilt-shaped bipedal robot described in "Vol. 1, No. 3, pp. 176-181, October 1983" has also been proposed. The walking robot proposed here can change its gait by calculating joint angles in real time, but this type of stilt-shaped robot has fewer degrees of freedom, so there are restrictions on its gait and walking location. There are some inconveniences.

Therefore, an object of the present invention is to provide an autonomous legged mobile robot that walks based on a preset walking pattern and is capable of changing its gait in real time midway through walking. The objective is to propose a walking control device.

Furthermore, when controlling the walking of such legged mobile robots, a control device consisting of a microcomputer is generally installed to determine control values, but in this case, the control device becomes large. Therefore, the second object of the present invention is to provide a small and lightweight control device suitable for mounting on a robot, which is capable of changing the gait in real time during walking. The purpose of this study is to propose a walking control device for a legged mobile robot.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention includes, for example, claim 1.
In the gait control device for a legged mobile robot that controls gait by driving a link mechanism consisting of a base link and a plurality of leg links coupled thereto, according to the planned gait of the robot, Target value setting means for setting time-series target values in advance for walking parameters including at least the center of gravity position of the link mechanism; the output of the target value setting means is inputted, and the base body position is determined from the set center of gravity position. posture angle calculating means for calculating the posture angle of the robot; control value determining means for inputting the output of the posture angle calculating means and determining a joint drive control value of the link mechanism based on the calculated posture angle; It is configured to include an actuator that receives the output of the control value determining means and drives the joint.

(Function) Parameters such as the position of the center of gravity, which is a higher concept than joint angles, are set as the walking pattern, and the posture angle of the robot is determined based on that, the joint angles are calculated, and the control values are then determined. It was configured to do so. That is, since the joint angles are determined in real time while walking without setting them in advance, it becomes possible to arbitrarily change the gait while walking as necessary.

(Example) Hereinafter, the present invention will be described in detail by taking a bipedal walking robot as an example of a two-legged walking robot. FIG. 1 is an explanatory skeleton diagram showing the entire robot 1, and each of the left and right legs has six joints (axes). The six joints (
From top to bottom, the joints (axis) for rotation of the legs at the waist (IOR)
, l0L (the right side is R1, the left side is L; the same applies hereinafter), the hip pitch direction joints (axes) 12R, 12L, the same roll direction joints (axes) 14R, 14L, the pitch direction joints (axis) of the 11th part. ) 16R, 16L, ankle joint (axis) in the pitch direction 18R, 18L, joint (axis) in the roll direction 2O
R, 2OL, and at the bottom there are foot parts 22R, 2OL.
2L is attached, and the torso (upper body) 2 is attached to the top.
4 is provided. In the above, the hip joint is joint (axis) 1
From 0R(L), 12R(L), and 14R(L), the ankle joint is composed of joints (axes) 18R(L) and 2OR(L). Also, between the hip joint and knee joint is the thigh link 27R, 2.
7L, lower leg link 28R between the knee joint and ankle joint,
Connected with 28L.

2 and 3 are sectional views specifically showing the hip joint region of the lower back schematically shown in FIG. 1. As shown in FIG. 2, the body section 24 is mounted on a lumbar plate 30 corresponding to a human pelvis, and the left and right legs are connected via the lumbar plate 30 to constitute a moving means of the robot. As shown in FIG. 1, the legs including the hip joints are symmetrical, so the right leg will be explained below.

In FIG. 2, there is a first harmonic reducer (trade name) 32 inside the waist plate 30, a pulley 34 is attached to its input shaft, and a first electric motor 36 is connected via a belt 35. Driving force is transmitted. As is well known, when the input shaft of the reducer 32 is rotated, a relative movement occurs between the flex ring 38, the fixed ring 40, and the output ring 42, and the rotation of the first electric motor 36 is reduced. Then,
Since the fixing ring 40 is bolted to the waist plate 30 and the output ring 42 is bolted to the output member 44, the first electric motor 3
6, the waist plate 30 and the output member 44 rotate relative to each other about the joint axis 10R described above.

A first yoke member 50 is bolted to the output member 44 at a lower portion thereof. The upper part of the first yoke member is a cavity 51 to accommodate a second electric motor 52 laterally. The output of the second electric motor 52 is inputted via the belt 54 to a second harmonic reducer 56 located below it, and the second harmonic reducer 56 decelerates and boosts the input rotation, and the output ring 58 to drive. The fixing ring 60 of the second harmonic reducer 56 is bolted to the lower left side of the first yoke member 50, and the output ring 58 is attached to the upper end of the thigh link 27R located below the first yoke member 50. Since the first yoke member 50 and the thigh link 27R rotate relative to each other by the operation of the second electric motor 52, the thigh link 27R in the figure rotates relative to the thigh link 27R about the joint axis 14R in the roll direction described above. Rotate. Further, the lower portion of the first yoke member 50 constitutes a bearing portion on the right side thereof, and supports the thigh link 27R in cooperation with the output member 62.

Further, as clearly shown in FIG. 3, the upper part of the thigh link 27R constitutes a second yoke member 71, which is bridged between the left and right yokes and inputs torque to the third harmonic reducer 72. A third electric motor 74 is arranged in series in the lateral direction, and its output is immediately input to the third harmonic reduction gear 72. The fixing ring 7
6 is coupled to the second output member 62 described above, and its output ring 78 is coupled to the second yoke member 71. Therefore, when the third electric motor 74 is driven, the output member 62 and the second Relative rotation occurs between the yoke member 71 and
In the figure, the thigh link 27R is rotated about the pitch axis 12R. Here, as illustrated, the axes 10R, 12
R and 14R intersect orthogonally to each other at point A (FIG. 3), and are configured so that their angular positions can be calculated by transformation of the orthogonal coordinate system.

Continuing the explanation toward the road side, in FIG. 2, a recess 79 is formed on the upper end side of the thigh link 27R, and a fourth electric motor 80 is housed therein, and its output is sent to the lower knee joint. It will be done. 4 and 5 show the parts below the knee joint, and the output of the fourth electric motor 80 is transferred to a fourth harmonic reducer 84 attached to the knee joint (shaft) 16R via a belt 82. is input to the input shaft of Note that a cavity 85 is formed inside the knee joint 16R to reduce the weight.

In addition, the knee joint (axis) 16R and the ankle joint are the lower leg link 28.
A recess 87 is formed on the upper end side of the R, and a fifth electric motor 88 is housed therein, and its output is transmitted via a belt 90 to a fifth harmonic reducer disposed at the ankle. 92 is input, and the foot portion 22 is driven in the pitch direction about the axis 18R described above. Also, axis 1
The foot portion 2 is centered on the axis 20R that is orthogonal to 8R.
2 is configured to be able to freely swing in the roll direction, and for this purpose, a sixth harmonic reduction gear 94 and a sixth electric motor 96 that supplies power thereto are directly connected to each other.

Here, electric motor 36.52, 74.8088.96
Rotary encoder 37, 53.75, 81.89
(for the sixth electric motor is not shown) is provided to detect the rotation angle of the motor shaft. In addition, a 6-axis force sensor 98 is provided at the ankle to measure the applied load and the like to determine whether the leg is a supporting leg or a free leg, and a known ground switch 99 is provided at the four corners of the sole of the foot. The presence or absence of grounding is detected (not shown in FIGS. 4 and 5). Further, as shown in FIG. 1, a pair of inclination angle sensors 100 and 102 are installed at appropriate positions on the body section 24, and measure the inclination with respect to the Z axis in the X2 plane and its angular velocity, as well as the 2 in the yz plane. Detect the tilt with respect to the axis and its angular velocity. Here, the movement in the xz plane is defined as the movement in the front-rear (pitch) direction, and the movement in the yz plane is defined as the movement in the left-right (roll) direction. These outputs are sent to the control unit 26 within the fuselage section 24 described above.

FIG. 6 is a block diagram showing details of the control unit 26, in which the outputs of the tilt sensors 100, 102, etc. are converted into digital values by the A/D conversion circuit 104, and the outputs are transferred to the bus 1.
It is sent to RAMIO3 via 06. Further, the outputs of the encoder 37 and the like are input into the RAM 108 via the counter 110, and the outputs of the ground switch 99 and the like are similarly stored in the RAM 108 via the waveform shaping circuit 112. Two arithmetic units 114 and 116 each consisting of a CPU are provided within the control unit, and the arithmetic unit 114 reads the gait data stored in the ROM 122 as described later, and also reads the gait data when there is a gait change command. corrects it, calculates the joint angle and link angle command values, and stores it in RAM10.
Output to B. In addition, the arithmetic unit 116 has RAM as described below.
Read the joint angle and link angle command values and detected actual measured values from 10B, calculate the control values necessary for each joint, and
/A conversion circuit 124 to servo amplifier 126. The control value is then converted into a current value and supplied to the electric motor of each joint. The reference numeral 128 indicates a joystick for commanding changes to the gait such as the course and stride length, the reference numeral 130 indicates an origin switch for correcting the inclination sensor, and the reference numeral 132 indicates a rim switch for failure.

FIG. 7 is a flow chart showing the operation of this device.

To explain with reference to the same figure, first, at slo, time t(n)
As the zero gait data for reading the gait data, the position of the center of gravity, the position of multiple legs, the direction of multiple legs, and the inclination of multiple legs are described as time series data or a function of time. As shown in FIG. 8, the center of gravity position G is the value Gx on the x, y, and z axes in the absolute coordinate space.

Gy and Gz are calculated offline in advance and set in the ROM. Note that in the first embodiment, the value on the z-axis does not matter. Positions Rx and Ry of each leg 22R and L
, Rz, Lx, Ly, and Lz are also set in advance in the x-y, x-z, and y-z spaces as shown in Figures 9 and 10 (Figure 10 (a) is the walking data is the toe position, and FIG. 10(b) shows the case when the walking data is the heel position.The position of each foot as the walking data is set in the absolute coordinate space, and FIGS. What is shown in the figure is a diagram that has been subjected to coordinate transformation in order to calculate each joint angle, which will be described later). Direction of each foot θRZ, θLZ
are also set on <
LX and θLY are also set as shown in FIG. 13 (showing χ-2 space).

Next, when there is a change in the gait such as the direction of travel or course in S12, a change command is inputted, the gait data set in S14 is corrected according to the change command, and the step is performed in S16.
If the hip position is not moved, the current joint angle is calculated.

To summarize this control here, in this control, the walking data is not joint angles and link angles, but position information that is a higher level concept. Therefore, joint angles and link angles are calculated moment by moment while walking, but in order to calculate them at a certain time and determine command values, it is necessary to
It is first necessary to determine the attitude of the Since the biped robot according to the embodiment has 12 degrees of freedom in total for both legs, its posture is determined by the position of the waist, the direction of the upper body (torso), the inclination of the upper body, the position of each foot, and the position of each foot. Once the orientation of the legs and the inclination of each leg are determined, 12 parameters are determined based on the waist, which is necessary and sufficient to determine the joint angles and link angles.

In this control, joint angles and link angles are calculated in real time in this manner, and then command values for each joint are calculated and controlled.

Here, the position Cz of the waist is set at an appropriate position between the hip joint (axis) IOR,L and the torso section 24, as shown in FIG. In the figure, the symbol Ln indicates the length of each link such as the thigh links 27L and R, Rnx, ny, and nz indicate the joint angles on the right leg side, and Lnx, ny, and nz indicate the joint angles on the left leg side. . The direction θCZ of the upper body (torso) is the average value of the directions θRZ and θLZ of the legs, as shown in FIG. The inclinations θCX and θCY of the upper body can be detected as shown in FIG. 15 from the output values of the above-mentioned inclination angle sensor. Note that when determining the posture angle, the inclination of the upper body is assumed to be zero in both the left-right and front-back directions. As a result, the leg side can also be positioned using absolute coordinates based on the absolute angle of the torso and the relative detection angle of the encoder on the leg link side. Additionally, the position, orientation, and inclination of each foot are determined from walking data.

Therefore, in S16, such parameters are determined and joint angles are calculated. Figures 9, 10 and 1
Examples of calculation in the xz, y2 space are shown in FIGS. 6 to 19. As shown in the figure, the angle is calculated using a geometric method while performing coordinate transformation. As shown there, when the knee is extended (Figures 16 and 18) and when the knee is bent (Figure 1).
The position of the waist is different in Figure 7). Therefore, in this embodiment, the vertical position of the waist is determined so that either the left or right knee or both knees are extended. To explain specifically with reference to FIG. 13, L=L3+L4 LRx=aRx LRy=aLy LLx=aLx" L Ly=aLy" L Rz"= L"-L Rx"-L Ry"L
Lz"= L"-L Lx"-L Ly"LRz=
Both knees extend when doing LLz.

Cz = aRz + LRz + L2 =a　LX　+LLZ　+L2 When LR2<LLZ The right knee extends.

Cz = aRz + LRz + L2L Lz <
When doing L Rz, the left knee extends.

Cz = a Lz 0 LLz + L2 In other words, it can be considered that at least one knee is always extended while walking, so one of the above conditional expressions can be used alternatively to determine the position of the hip. can do.

Next, the position of the center of gravity in the case where the position of the waist is not moved after reaching 31B is calculated. That is, from the state shown in FIG. 19 to the state shown in FIG.
As shown in the figure, when it becomes necessary to change the posture in response to the gait change command in S12, first the center of gravity position is determined with the hip position, which is the core in determining the posture, remaining as it is. calculate. This is the same even when no change command is issued in SI2, and the actual center of gravity position is calculated in this step in order to find the deviation from the center of gravity position in the walking data.

Note that in this example, the value of the center of gravity position on the Z axis does not matter.

Assuming that a change command has been issued, the target center of gravity position can be calculated from the new target posture accordingly, and the deviation between the target center of gravity position and the current center of gravity position is calculated in S20. Then, in S22, the deviation is multiplied by a predetermined coefficient to calculate the movement correction amount of the hip position. χ for this coefficient.

ky is set appropriately, but for example, kx=
It may be made variable such as 0.1, ky=0.9, etc.

Next, in S24, a new hip position is calculated by adding up the correction amount to the current position as shown in FIG. 21, and in S26, joint angles are calculated again based on the new posture determined in this way.
In step 8, the deviation from the joint angle calculated in step 316 is determined, and a joint drive control value is determined and outputted in order to reduce the deviation.

In this embodiment, for example, when a request is made to change the landing position 10 CI ahead while walking, the deviation between the target center of gravity position corresponding to the changed landing position and the current center of gravity position is calculated, and then the posture is changed. Since the joint angles are calculated after determining the posture by roughly estimating the amount of corrected movement of the hip position, which is a core parameter when determining, the gait can be changed arbitrarily in the middle of walking. That is, the center of gravity position and landing position are set in advance as walking data, the posture is determined as appropriate according to the walking condition, the joint angle is calculated, and the joints are driven based on this. Furthermore, since the joint angles are calculated simply using a geometric method as shown in the figure, they can be easily realized using a small and lightweight control device. Furthermore, since the upper and lower (two-axis) directions are not constrained when determining the position of the waist, posture determination and joint angle calculation are further simplified. Furthermore, since positioning using absolute coordinates is possible, the posture angle of the robot can be accurately detected, allowing stable walking.

FIG. 22 is a flow chart showing a second embodiment of the present control device. As shown, the difference from the first embodiment is that in steps 3108 to 114, the waist position and center of gravity position are determined in a three-dimensional absolute coordinate space including the Z-axis direction. As a result, although calculations are slightly more complicated than in the first embodiment, positioning can be performed more accurately. Note that the remaining steps are the same as in the first embodiment.

Although the present invention has been described using a bipedal walking robot as an example, the present invention is not limited thereto, and is also applicable to legged mobile robots with three or more legs.

(Effect of the invention) The walking control device for a legged mobile robot according to claim 1 has the following features:
The configuration is configured such that time-series target values are set in advance for walking parameters including at least the center of gravity position, the base body position is determined from the set center of gravity position, the posture angle of the robot is calculated, and joint drive control values are determined. Therefore, since we do not have joint angles as preset data and calculate the joint angles themselves in real time, the posture is not constrained from the walking data, and therefore it is possible to adjust the joint angles in the middle of walking as necessary. You can change your gait at will. Furthermore, since the calculation method is simplified, it can be realized with a small and lightweight control device suitable for being mounted on a two-legged mobile robot. The specific configuration thereof is as described in claim 2.

A walking control device for a leg hole mobile robot according to claim 3 includes:
Since the position is configured to be a position in at least two-dimensional space, calculation can be performed easily.

A walking control device for a leg hole mobile robot according to claim 4 includes:
Since the above-mentioned position is configured to be a position on at least a three-dimensional absolute coordinate space, the calculation itself is somewhat complicated, but
The attitude angle can be determined more accurately.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the overall walking control device for a leg-hole mobile robot according to the present invention, Fig. 2 is a sectional view showing the structure of the hip joint in detail, and Fig. 3 is a line taken along the line ■-■ in Fig. 2. Cross section, 4th
The figure is an explanatory side view showing the parts below the knee joint in Figure 1, and Figure 5.
The figure is a partial sectional view taken along line V-v, Figure 6 is an explanatory block diagram of the control unit, Figure 7 is a flow chart showing the operation of this control device, and Figure 8 shows the position of the center of gravity on the absolute coordinate space. FIG. 9 is an explanatory diagram showing the position of the foot in x-y space, and 10th area (a) and (b) are explanatory diagrams similarly showing the position of the foot in x-z space. Fig. 11 is an explanatory diagram showing the orientation of the upper body and legs in x-y space, and Fig. 12 is an explanatory diagram showing the orientation of the upper body and legs in x-y space.
An explanatory diagram showing the direction of the foot in space, FIG. 13 is also x
- An explanatory diagram showing the inclination of the foot in the z space, Fig. 14 is an explanatory diagram showing the position of the waist, etc., Fig. 15 is an explanatory diagram showing the inclination of the upper body, etc., and Fig. 16 is an explanatory diagram showing the inclination of the upper body, etc. in the x-z space. FIG. 17 is an explanatory diagram showing a method for calculating joint angles when the knee is bent in x-z space, and FIG. 18 is an explanatory diagram showing a method for calculating joint angles when the knee is bent in x-z space. An explanatory diagram showing the method of calculating the joint angle with the knee bent in z space, Figures 19 to 21 are explanatory diagrams showing the movement progress of the waist and center of gravity in xy space, and Figure 22 is the main It is a flow chart showing a second embodiment of the invention. 1... Leg hole mobile robot (biped walking robot) 10R
, IOL... joints (axes) for leg rotation 12R, 12L
...Joints (axis) in the pitch direction of the crotch, 14R, 14L
... Joints (axis) in the roll direction of the crotch, 16R, 16L
...The pitch direction of the knee! fli (axis), 18R
, 18L... Joint (axis) in the pitch direction of the ankle, 2O
R, 2OL... joint (axis) in the roll direction of the ankle, 2
2R. 22L... Leg part, 24... Torso part, 26... Control unit, 27R, 27L... Thigh link, 28R,
28L...Lower leg link, 30...Waist board, 32.56
,72,84,92.94...harmonic reducer,
34...Pulley, 35.54,82.90...Belt, 36,5274.80.88.96...Electric motor, 37.53,75.81.89...Rotary encoder, 38. ...Flex ring, 40, 60.7
6... Fixed ring, 42.58.78... Output ring, 44.62... Output member, 50.71... Yoke member, 51.85... Cavity, 79.87... Recessed part, 98... 6-axis force sensor, 99... Earthing switch,
100, 102... Tilt angle sensor, 104... A/
D conversion circuit, 106... Lotus, 108... RAM,
110...Counter, 112...Waveform shaping circuit 11
4.116... Arithmetic device (sub system), 122
...ROM, 124...D/A conversion circuit, 126.
...Servo amplifier, 128...Joystick, 1
30... Origin switch, 132... Limit switch

Claims (4)

[Claims] (1) In a gait control device for a legged mobile robot that controls gait by driving a link mechanism consisting of a base link and a plurality of leg links coupled to the base link, a. , target value setting means for setting time-series target values in advance for walking parameters including at least the center of gravity position of the link mechanism; b. inputting the output of the target value setting means, and adjusting the base position from the set center of gravity position; a posture angle calculation means for determining the posture angle of the robot and calculating the posture angle of the robot; A walking control device for a legged mobile robot, comprising: a value determining means; and d, an actuator that inputs the output of the control value determining means and drives the joint. (2) A gait control device for a legged mobile robot that controls gait by driving the joints of a link mechanism consisting of a base link and a plurality of leg links coupled thereto, comprising: a. the planned gait of the robot; According to the gait parameters including at least the center of gravity position of the link mechanism,
target value setting means for setting time-series target values in advance; b. inputting the output of the target value setting means, determining the base position from the set center of gravity position and calculating the first posture angle of the robot; c. Gait change command means for instructing a change in the robot's planned gait during the robot's walk; d. Target value setting means; first posture angle calculation. When a change in gait is commanded, the center of gravity position is calculated and the deviation from the set center of gravity position is determined, and the base position is adjusted according to the deviation. a second posture angle calculation means for calculating a corrected value of the posture angle of the robot by changing the posture angle; e. inputting the outputs of the first and second posture angle calculation means;
control value determining means for determining a joint drive control value of the link mechanism based on a first attitude angle or a second attitude angle; and f, an actuator that inputs the output of the control value determining means to drive the joint. A walking control device for a legged mobile robot, comprising: (3) The walking control device for a legged mobile robot according to claim 1 or 2, wherein the position is a position in a space of at least two dimensions or more. (4) The walking control device for a legged mobile robot according to claim 3, wherein the position is a position on a three-dimensional absolute coordinate space.