JP2016112656A - Posture stabilization control device for bipedal walking robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a posture stabilization control device for a bipedal walking robot capable of achieving posture stabilization by a novel method when unexpected external force is applied to a bipedal walking robot during walking.SOLUTION: A target acceleration calculation part 61 calculates center-of-gravity target acceleration aand idling leg target acceleration αat the time when external disturbance is not occurring on the basis of target waist position data. A center-of-gravity actual acceleration calculation part 62 calculates center-of-gravity actual acceleration aon the basis of an output signal of an acceleration sensor 47. An external force acceleration calculation part 65A calculates external force acceleration a on the basis of the center-of-gravity target acceleration aand the center-of-gravity actual acceleration a. An external force reduction acceleration calculation part 65B calculates external force reduction acceleration α on the basis of the external force acceleration a. An idling leg position correction amount calculation part 65C calculates an idling leg position correction amount for generating acceleration which adds the external force reduction acceleration α to the idling leg target acceleration α, in the idling leg.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a posture stabilization control device for a biped robot.

  In a biped robot, it is important to stabilize the posture in order to prevent falling when it receives disturbance during walking. As posture stabilization technology, a method of stabilizing the posture by moving the center of gravity of the biped walking robot, a method of stabilizing the posture by changing the landing position of the leg of the free leg, and the like have been proposed.

JP 2003-326383 A Published by Shuji Hamada, “Humanoid Robot”, Ohm Co., Ltd., May 20, 2014, 1st edition, 8th edition

The present applicant has studied the method of stabilizing the posture by focusing on the inertia (mass / acceleration) of the free leg, not the landing position of the free leg, and has come up with the invention here.
An object of the present invention is to provide a posture stabilization control device for a biped robot that can stabilize posture by a novel method when an unexpected external force is applied to the biped robot during walking.

  In order to achieve the above object, the invention according to claim 1 includes a pair of left and right legs (2L, 2R), and stabilizes the posture of a biped robot (1) that is controlled for walking based on target gait data. An external force acceleration calculating means for calculating an external force acceleration that is an acceleration given to the biped walking robot by the external force when an unexpected external force is applied to the biped walking robot during walking. 61, 62, 65A) and free leg control for causing the free leg of the biped robot to generate a reaction force for reducing the external force based on the external force acceleration calculated by the external force acceleration calculating means. And a posture stabilization control device for a biped robot, including means (65B, 65C, 66). In addition, although the alphanumeric characters in parentheses represent corresponding components in the embodiments described later, of course, the scope of the present invention is not limited to the embodiments. The same applies hereinafter.

In this configuration, when an unexpected external force is applied to the biped walking robot during walking, a reaction force for reducing the external force can be generated by the free leg. Thereby, posture stabilization can be achieved.
The invention according to claim 2 further includes free leg target acceleration calculating means (61) for calculating a target acceleration of the free leg when no unexpected external force is generated based on the target gait data, The free leg control means calculates external force reduction acceleration calculation means (65B) for calculating the external force reduction acceleration necessary for generating the reaction force by the free leg based on the external force acceleration calculated by the external force acceleration calculation means. ) And the free leg target acceleration calculated by the free leg target acceleration calculating means plus the external force reducing acceleration calculated by the external force reducing acceleration calculating means. The biped walking robot posture stabilization control apparatus according to claim 1, further comprising leg acceleration control means (65C, 66).

  According to a third aspect of the present invention, the target gait data includes target free leg position data that is a target position of the free leg, and the free leg acceleration control means uses the free leg target acceleration to reduce the external force. 3. The posture stabilization control device for a biped robot according to claim 2, configured to correct the target swing leg position data so that an acceleration including an acceleration is generated in the swing leg. 4.

  The invention according to claim 4 is characterized in that the external force acceleration calculating means calculates the target acceleration of the center of gravity of the biped walking robot based on the target gait data; The center-of-gravity actual acceleration calculation means (62) for calculating the actual acceleration of the center of gravity of the walking robot, the center-of-gravity target acceleration calculated by the center-of-gravity target acceleration calculation means, and the center-of-gravity actual acceleration calculated by the center-of-gravity actual acceleration calculation means The posture stabilization control device for a biped robot according to any one of claims 1 to 3, including means (65A) for calculating external force acceleration.

FIG. 1 is a configuration diagram showing a joint configuration of a biped robot to which a posture stabilization control device for a biped robot according to an embodiment of the present invention is applied. FIG. 2 is a block diagram showing the configuration of the ECU. 3A, 3B, and 3C are explanatory diagrams for explaining a basic concept of posture stabilization control by the second stabilization control unit. FIG. 4 is a flowchart for explaining the operation of the posture stabilization control unit.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a configuration diagram showing a joint configuration of a biped robot according to an embodiment of the present invention. In FIG. 1, the front-rear direction, the left-right direction, and the height direction of the biped walking robot 1 are defined as an x-axis direction, a y-axis direction, and a z-axis direction, respectively.
A biped walking robot 1 (hereinafter simply referred to as “robot 1”) in FIG. 1 is a model having only a lower body that does not have an upper body, and includes a pair of left and right leg links 2L and 2R and leg links 2L and 2R. It includes feet 3L, 3R attached to the lower end (tip), and a waist (housing) 4 provided above the leg links 2L, 2R. The upper ends of the leg links 2L and 2R are connected to each other by a connecting link 5.

  Each leg link 2L, 2R includes hip joints (lumbar joints) 7L, 7R, knee joints 8L, 8R, and ankle joints 9L, 9R. The leg links 2L and 2R include thigh links 11L and 11R that connect the hip joints 7L and 7R and the knee joints 8L and 8R, and crus links 12L and 12R that connect the knee joints 8L and 8R and the ankle joints 9L and 9R. And ankle links 13L and 13R connecting the ankle joints 9L and 9R and the feet 3L and 3R.

  The hip joints 7L and 7R include electric motors 21L and 21R that rotate the thigh links 11L and 11R around the vertical axis (z axis) with respect to the waist 4. The hip joints 7L and 7R further have electric motors 22L and 22R that rotate the thigh links 11L and 11R in the roll direction (around the x axis) with respect to the waist 4, and the thigh links 11L and 11R with respect to the waist 4 in the pitch direction ( electric motors 23L and 23R that rotate about the y-axis).

  The knee joints 8L and 8R include electric motors 24L and 24R that rotate the lower leg links 12L and 12R about the y-axis with respect to the thigh links 11L and 11R. The ankle joints 9L and 9R include electric motors 25L and 25R that rotate the ankle links 13L and 13R about the y-axis with respect to the crus links 12L and 12R, and the ankle links 13L and 13R with respect to the crus links 12L and 12R. Electric motors 26L and 26R that rotate around. Each electric motor 21L-26L, 21R-26R consists of a servomotor in this embodiment. In this embodiment, motor drivers (servo amplifiers) 31L to 36L and 31R to 36R (see FIG. 2) are provided for the electric motors 21L to 26L and 21R to 26R, respectively.

As described above, each of the leg links 2L and 2R includes six electric motors 21L to 26L and 21R to 26R, and has a total of 12 degrees of freedom. By controlling the drive of the twelve electric motors 21L to 26L and 21R to 26R, a desired movement can be given to the leg links 2L and 2R, and the robot 1 can be arbitrarily walked.
The electric motors 21L to 26L and 21R to 26R are provided with rotation angle sensors 41L to 46L and 41R to 46R (see FIG. 2) for detecting their rotation angles. Output signals of these rotation angle sensors 41L to 46L and 41R to 46R are given to the corresponding motor drivers 31L to 36L and 31R to 36R. The waist 4 is provided with an acceleration sensor 47 for detecting accelerations before and after the center of gravity of the robot 1, left and right, and up and down. The waist 4 is provided with an ECU (Electronic Control Unit) 50 for controlling the motor drivers 31L to 36L and 31R to 36R.

FIG. 2 is a block diagram showing the configuration of the ECU 50.
An acceleration sensor 47 is connected to the ECU 50. The ECU 50 is connected to motor drivers 31L to 36L and 31R to 36R of the electric motors 21L to 26L and 21R to 26R. Output signals of the rotation angle sensors 41L to 46L and 41R to 46R are input to the ECU 50 via the motor drivers 31L to 36L and 31R to 36R. The ECU 50 is composed of a microcomputer.

The ECU 50 functions as a plurality of function processing units by executing a predetermined program. The plurality of function processing units include a gait generation unit 51, a posture stabilization control unit 52, and a motor command value calculation unit 53.
The gait generator 51 generates target gait data (walking pattern data) for controlling the robot 1 to walk. In this embodiment, the target gait data includes target waist position data, target support leg position data, and target free leg position data. The target waist position data, the target support leg position data, and the target swing leg position data are time-series data for each predetermined calculation cycle. The target waist position is the target position of the waist 4 and is the target position of the center of gravity of the robot 1. The target support leg position is a target position of the support leg (the center of gravity of the support leg). The support leg is a leg that is in contact with the floor. The target free leg position is the target position of the free leg (the center of gravity of the free leg). A free leg is a leg away from the floor. These target gait data are generated so that the center of gravity of the robot 1 is always located at a stable position based on a preset stride, a leg raising amount, or the like.

The gait generator 51 receives output signals from the rotation angle sensors 41L to 46L and 41R to 46R. In this embodiment, the gait generator 51 recalculates the desired gait data at each timing when both the leg links 2L and 2R arrive on the floor.
The posture stabilization control unit 52 performs posture stabilization control for preventing the robot 1 from falling over when the posture of the robot 1 becomes unstable due to disturbance during walking. The posture stabilization control unit 52 includes a target acceleration calculation unit 61, a center-of-gravity actual acceleration calculation unit 62, a first stabilization control unit 63, a first addition unit 64, a second stabilization control unit 65, and a second And an adder 66.

Based on the target gait data generated by the gait generator 51, the target acceleration calculator 61 determines the target acceleration of the center of gravity of the robot 1 (hereinafter referred to as “center of gravity target acceleration a _T ”) and the play of the robot 1. A target leg acceleration (hereinafter referred to as “free leg target acceleration α _T ”) is calculated. a _T and α _T represent acceleration vectors. Specifically, the target acceleration calculator 61, based on the target waist position data, calculates the center of gravity target acceleration a _T when the disturbance has not occurred. The target acceleration calculator 61, based on the target free leg position data, calculates the swing target acceleration alpha _T when the disturbance has not occurred.

Based on the output signal of the acceleration sensor 47, the center-of-gravity actual acceleration calculation unit 62 calculates an actual acceleration near the center of gravity of the robot 1 (hereinafter referred to as “center-of-gravity actual acceleration a _S ”). a _S represents an acceleration vector.
As is well known, the first stabilization control unit 63 controls the support leg and waist position of the robot 1 when an unexpected external force (disturbance) is applied to the robot 1, so that the center of gravity of the robot 1 The posture of the robot 1 is stabilized by moving the position onto the support leg. That is, the first stabilization control unit 63 stabilizes the posture of the robot 1 by controlling the position of the center of gravity of the robot 1. The first stabilization control unit 63 performs general control for changing the support leg and the waist position, moving the center of gravity position, and stabilizing the posture. The first addition unit 64 adds the waist position correction amount calculated by the first stabilization control unit 63 to the target waist position data generated by the gait generation unit 51. Thereby, the target waist position data is corrected.

The second stabilization control unit 65 stabilizes the posture of the robot 1 by controlling the acceleration of the free leg of the robot 1 when an unexpected external force (disturbance) is applied to the robot 1.
First, the basic concept of attitude stabilization control by the second stabilization control unit 65 will be described.
When the free leg of the robot 1 is moved, a force in the opposite direction (reaction force) acts on the waist 4 with respect to the force for moving the free leg. The reaction force depends on the acceleration of the free leg. For example, the reaction is small when the free leg is operated slowly from a standstill with one leg standing, and the reaction is large when the swing leg is operated suddenly. Therefore, when an external force is applied to the robot 1, the external force can be reduced by controlling the acceleration of the free leg of the robot 1.

  As shown in FIG. 3A, it is assumed that an external force F (vector) is applied to the center of gravity of the robot 1. When the mass of the center of gravity of the robot 1 is M and the acceleration (vector) given to the center of gravity of the robot 1 by the external force F is a, the external force F is F = M · a. As shown in FIG. 3B, when the force for operating the free leg of the robot 1 is f (vector), the mass of the free leg is m, and the acceleration (vector) of the free leg is α, The force f is f = m · α. The reaction force acts on the waist 4 in the direction opposite to the force f for operating the free leg. That is, the reaction force is −f. Therefore, as shown in FIG. 3C, the external force F can be reduced by generating a reaction force (−f) in the opposite direction to the external force F by the free leg.

When a reaction force having the same magnitude as the external force F is generated by the free leg, the external force F is canceled by the reaction force (−f). However, there is a limit to the acceleration that can be applied to the free leg, and extremely large acceleration may cause failure of the electric motor or machine, so the free leg generates a reaction force as large as the external force. It can be difficult to do.
Therefore, in order to reduce the external force, a reaction force (−f) that satisfies the following expression (1) is generated by the free leg.

F + (− f) ≦ δ (1)
δ (> 0) is a preset threshold value. From the formula (1), the following formula (2) is obtained.
F−f = M · a−m · α ≦ δ (2)
Therefore, the acceleration α to be generated on the free leg in order to reduce the external force F is expressed by the following equation (3).

α = (M · a−δ) / m (3)
If a in equation (3) is an acceleration given to the center of gravity of the robot 1 by an unexpected external force, the acceleration α to be generated in the free leg to reduce the unexpected external force is calculated by the equation (3). Can do. Acceleration a applied to the center of gravity of the robot 1 due to an unexpected external force, using the target acceleration centroid target acceleration calculated by the calculating unit 61 a _T and the center of gravity actual acceleration calculating unit 62 centroid actual acceleration a _S calculated by the following It can be calculated based on the equation (4).

a = a _T −a _S (4)
Returning to FIG. 2, the second stabilization controller 65 includes an external force acceleration calculator 65A, an external force reduction acceleration calculator 65B, and a free leg position correction amount calculator 65C.
The external force acceleration calculation unit 65A calculates an acceleration (hereinafter referred to as “external force acceleration a”) applied to the robot 1 by an unexpected external force, based on the equation (4). The external force reduction acceleration calculation unit 65B uses the external force acceleration a and the equation (3) to calculate an acceleration for reducing an unexpected external force (hereinafter referred to as “external force reduction acceleration α”). The free leg position correction amount calculation unit 65C is a free leg position for causing the free leg to generate an acceleration obtained by adding an external force reduction acceleration α to the free leg target acceleration α _T when an unexpected external force (disturbance) is not generated. Calculate the correction amount.

The second adder 66 adds the free leg position correction amount calculated by the second stabilization controller 65 to the target free leg position data generated by the gait generator 51. Thereby, the target free leg position data is corrected.
The target acceleration calculation unit 61, the center-of-gravity actual acceleration calculation unit 62, and the external force acceleration calculation unit 65A in the second stabilization control unit 65 constitute external force acceleration calculation means of the present invention. The external force reduction acceleration calculation unit 65B, the free leg position correction amount calculation unit 65C, and the second addition unit 66 in the second stabilization control unit 65 constitute the free leg control means of the present invention. The external force reduction acceleration calculation unit 65B constitutes the external force reduction acceleration calculation means of the present invention. The free leg position correction amount calculation unit 65C and the second addition unit 66 constitute free leg acceleration control means of the present invention.

  The motor command value calculator 53 rotates the rotation angles of the electric motors 21L to 26L and 21R to 26R based on the corrected target waist position data, the target support leg position data, and the corrected target swing leg position data. Calculate the command value. And the motor command value calculating part 53 gives the control signal according to the rotation angle command value of each electric motor 21L-26L, 21R-26R to corresponding motor driver 31L-36L, 31R-36R. Thereby, each motor driver 31L-36L, 31R-36R is the rotation angle to which the actual rotation angles of the electric motors 21L-26L, 21R-26R detected by the corresponding rotation angle sensors 41L-46L, 41R-46R correspond. The corresponding electric motor is driven so as to match the command value.

  Through the above operation, the robot 1 basically performs a walking operation according to the target gait data generated by the gait generator 51. When an unexpected external force is applied to the robot 1 during walking, posture stabilization control by the posture stabilization control unit 52 is performed. Specifically, posture stabilization control based on center-of-gravity position control by the first stabilization control unit 63 and posture stabilization control based on free leg acceleration control by the second stabilization control unit 65 are performed. Thereby, even if an unexpected external force is applied to the robot 1 during walking, the robot 1 can be effectively prevented from falling.

FIG. 4 is a flowchart showing the operation of the posture stabilization control unit 52. The process of FIG. 4 is repeatedly executed at every predetermined calculation cycle.
Target acceleration calculating unit 61, as well as calculating the center of gravity target acceleration a _T based on the target waist position data generated by the gait generator 51, based on the target free leg position data generated by the gait generator 51 calculates the swing target acceleration alpha _T (step S1). The center-of-gravity actual acceleration calculation unit 62 calculates the center-of-gravity actual acceleration a _S based on the output signal of the acceleration sensor 47 (step S2).

Force acceleration calculator 65A uses the centroid target acceleration a _T and the center of gravity actual acceleration a _S, based on the equation (4), calculates the external force acceleration a (step S3). The external force acceleration calculation unit 65A determines whether or not the magnitude of the external force acceleration a is equal to or greater than a predetermined threshold value η (η> 0) (step S4). When the magnitude of the external force acceleration a is less than the predetermined threshold η (step S4: NO), the posture stabilization control unit 52 ends the processing of the current calculation cycle. In this case, since the correction amount is not calculated by the first stabilization control unit 63 and the second stabilization control unit 65, the target waist position data and the target free leg position data are not corrected.

If it is determined in step S4 that the magnitude of the external force acceleration a is greater than or equal to the predetermined threshold η (step S4: YES), the external force reduction acceleration calculation unit 65B is based on the equation (3). Then, the external force reducing acceleration α is calculated (step S5). The free leg position correction amount calculating unit 65C is the acceleration of external force reduction acceleration alpha to swing target acceleration alpha _T, it calculates the free leg position correction amount for generating the swing (step S6). The second adder 66 adds the free leg position correction amount to the target free leg position data generated by the gait generator 51 (step S7). Thereby, the target free leg position data is corrected.

Thereafter, the first stabilization control unit 63, based on the center of gravity target acceleration a _T and the center of gravity actual acceleration a _S, calculates the waist position correction amount (step S8). The first adder 64 adds the waist position correction amount to the target waist position data generated by the gait generator 51 (step S9). Thereby, the target waist position data is corrected. Then, the posture stabilization control unit 52 ends the processing of the current calculation cycle.

  As mentioned above, although one Embodiment of this invention was described, this invention can be implemented with another form. In the above-described embodiment, the acceleration at the center of gravity of the robot 1 is detected by the acceleration sensor 47 provided in the waist 4. However, each foot 3L, 3R may be provided with a force sensor capable of detecting a ZMP (Zero Moment Point), and the acceleration of the center of gravity of the robot 1 may be calculated based on the output signals of these force sensors. . Specifically, the ZMP of the support leg is obtained from a force sensor provided on the support leg. Then, the acceleration of the center of gravity of the robot 1 is calculated using the ZMP of the support leg, the position of the center of gravity of the robot, and the table / cart model (see P140-P141 of Non-Patent Document 1).

Moreover, although the case where this invention was applied to the biped walking robot which consists only of a lower half body was demonstrated in the said embodiment, this invention is applicable also to the bipedal walking robot provided with the lower half body and the upper half body.
The present invention can be modified in various ways within the scope of the matters described in the claims.

  DESCRIPTION OF SYMBOLS 1 ... Biped walking robot, 2L, 2R ... Leg link, 4 ... Lumbar part (casing), 7L, 7R ... Hip joint (lumbar joint), 8L, 8R ... Knee joint, 9L, 9R ... Ankle joint, 21L-26L , 21R to 26R ... electric motor, 31L to 36L, 31R to 36R ... motor driver (servo amplifier), 41L to 46L, 41R to 46R ... rotation angle sensor, 47 ... acceleration sensor, 50 ... ECU, 51 ... gait generator 52 ... Attitude stabilization control unit, 53 ... Motor command value calculation unit, 61 ... Target acceleration calculation unit, 62 ... Center of gravity actual acceleration calculation unit, 63 ... First stabilization control unit, 64 ... First addition unit, 65 ... Second stabilization control unit, 65A ... external force acceleration calculation unit, 65B ... external force reduction acceleration calculation unit, 65C ... free leg position correction amount calculation unit, 66 ... second addition unit

Claims (4)

An apparatus for stabilizing the posture of a biped robot including a pair of left and right legs and controlled for walking based on target gait data,
An external force acceleration calculating means for calculating an external force acceleration which is an acceleration given to the biped walking robot by the external force when an unexpected external force is applied to the biped walking robot during walking;
Biped walking including a free leg control means for causing the free leg of the biped robot to generate a reaction force for reducing the external force based on the external force acceleration calculated by the external force acceleration calculating means. Robot posture stabilization control device. Based on the target gait data, further includes a free leg target acceleration calculating means for calculating a target acceleration of the free leg when no unexpected external force is generated,
The swing leg control means includes:
An external force reduction acceleration calculation means for calculating an external force reduction acceleration necessary for generating the reaction force by the free leg based on the external force acceleration calculated by the external force acceleration calculation means;
Free leg acceleration control for causing the free leg to generate an acceleration obtained by adding the external force reduction acceleration calculated by the external force reduction acceleration calculation means to the free leg target acceleration calculated by the free leg target acceleration calculation means The posture stabilization control device for a biped robot according to claim 1, further comprising: means. The target gait data includes target swing leg position data that is a target position of the swing leg,
The free leg acceleration control means is configured to correct the target free leg position data so that an acceleration obtained by adding the external force reduction acceleration to the free leg target acceleration is generated in the free leg. Item 3. A posture stabilization control device for a biped robot according to Item 2. The external force acceleration calculating means includes
A center-of-gravity target acceleration calculating means for calculating a target acceleration of the center of gravity of the biped robot based on the target gait data;
Centroid actual acceleration calculating means for calculating the actual acceleration of the centroid of the biped walking robot;
The center of gravity target acceleration calculated by the center of gravity target acceleration calculating means and the means for calculating external force acceleration based on the center of gravity actual acceleration calculated by the center of gravity actual acceleration calculating means. The posture stabilization control device for a biped robot according to claim 1.

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