Floor shape deducing device for legged mobile robot

• US 20030125839A1
• Filed: 11/19/2002
• Published: 07/03/2003
• Est. Priority Date: 05/19/2000
• Status: Active Grant

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Matsumoto, Takashi, Takenaka, Toru, Hasegawa, Tadaaki
• Granted Patent: US 6,920,374 B2
• Time in Patent Office: Days
• US Class Current: 700/245
• CPC Class Codes: B62D 57/02 with ground-engaging propulsion means, e.g. walking members
• CPC Class Codes: B62D 57/024 specially adapted for moving on inclined or vertical surfaces endless-track vehicles for ascending or descending stairs B62D55/075; hand-carts with provision for travelling up or down stairs B62B5/02
• CPC Class Codes: B62D 57/032 with alternately or sequentially lifted supporting base and legs; with alternately or sequentially lifted feet or skid B62D57/024 takes precedence

Abstract

A floor shape estimation system for a legged mobile robot, in particular a biped walking robot, which estimates a floor shape, more specifically a foot-to-foot floor inclination difference based on at least a control error of the total floor reaction force'"'"'s moment and based on the estimated value and corrects a feet compensating angle based on the estimated value. Further, the system estimates a floor shape, more specifically a foot floor inclination difference based on at least a control error of the foot floor reaction force about a desired foot floor reaction force central point and corrects a foot compensating angle based on the estimated value. With this, it can accurately estimate the shape of a floor with which the robot is in contact. Further, if the floor shape is different from what has been supposed, it can produce the floor reaction force as desired by absorbing the influence of difference.

Claims

1. A system for controlling a legged mobile robot having at least a body and a plurality of legs each connected to the body through a first joint and having a foot connected to its distal end through a second joint, the system having a compliance mechanism which deforms in response to a floor reaction force acting from a floor with which the foot is in contact and joint displacement means which displacing the first and second joints such that the foot follows a desired position and/or posture, comprising:

a. inclination detection means for detecting an inclination of the body relative to a vertical direction;

b. walking environment foot position and/or posture calculating means for calculating a position and/or posture of the foot in a walking environment including the floor with which the foot is in contact, based on an actual and/or desired position and/or posture of the foot and the detected inclination;

c. deformed foot position/posture calculating means for calculating the position and/or posture of the foot with deformation of the mechanism in response to the floor reaction force acting from the floor in the walking environment using a mechanism compliance model which models the compliance mechanism; and

d. floor shape estimation value calculating means for calculating a floor shape estimation value indicative of shape of surface of the floor with which each foot is in contact and indicative of a relationships therebetween.

2. A system according to claim 1, wherein the compliance model comprises a first model which expresses the floor reaction force acting on each foot and a change of position and/or posture of each foot resulting from the floor reaction force acting on each foot, and a second model which expresses the floor reaction force acting at a desired total floor reaction force central point and a change of one of the foot relative to the other resulting from the floor reaction force acting at the desired total floor reaction force central point.

3. A system according to claim 1 or 2, wherein the floor shape estimation value calculating means has a filter which removes a high-frequency component.

4. A system according to any of claims 1 to 3, further including:

e. correcting means for correcting the desired position and/or posture of the foot based on the calculated floor shape estimation value.

5. A system according to claim 4, further including:

f. gait generating means for generating a gait of the robot including at least a motion pattern of the robot including at least the desired position and/or posture of the foot and a desired pattern of a total floor reaction force acting on the robot;

g. desired foot floor reaction force central point determining means for determining a desired foot floor reaction force which is a central point of action on the foot when the total floor reaction force of the generated gait is distributed to each of the foot;

h. actual floor reaction force detecting means for detecting an actual floor reaction force acting on the foot; and

i. foot rotation amount determining means for calculating a moment of the detected actual floor reaction force acting about the calculated foot floor reaction force central point, and for determining a foot rotation amount for rotating the foot based on the calculated moment;

wherein the correcting means includes;

j. foot rotation amount correcting means for correcting the foot rotation amount based on the calculated floor shape estimation value; and

k. foot position/posture correcting means for correcting the desired position and/or posture of the foot based on the corrected foot rotation amount such that the position/posture of the foot rotates.

6. A system according to claim 4, further including:

l. gait generating means for generating gait of the robot including at least a motion pattern of the robot including at least the desired position and/or posture of the foot and a desired pattern of a total floor reaction force acting on the robot;

m. desired foot floor reaction force central point determining means for determining a desired foot floor reaction force which is a central point of action on the foot when the total floor reaction force of the generated gait is distributed to each of the foot;

n. actual floor reaction force detecting means for detecting an actual floor reaction force acting on the foot; and

o. foot rotation amount determining means for determining a foot rotation amount for rotating the foot based on the detected actual floor reaction force;

wherein the correcting means includes;

p. foot rotation amount correcting means for correcting the foot rotation amount based on the calculated floor shape estimation value; and

q. foot position/posture correcting means for correcting the desired position and/or posture of the foot based on the corrected foot rotation amounts such that the position and/or posture of the foot rotates about the determined foot floor reaction force central point or thereabout.

7. A system according to claim 5, wherein the foot position/posture correcting means corrects the desired position and/or posture of the foot based on the corrected foot rotation amounts such that the position and/or posture of the foot rotates about the determined foot floor reaction force central point or thereabout.

8. A system according to any of claims 5 to 7, further including:

r. foot movement amount determining means for calculating at least one of the total floor reaction force'"'"'s moment actually acting on the robot, and a moment obtained by subtracting the moment of the detected actual floor reaction force acting about the calculated foot floor reaction force central point, from the total floor reaction force'"'"'s moment actually acting on the robot, and for determining a foot movement amount for moving the foot based on the calculated moment.

9. A system according to any of claims 5 to 8, wherein the foot position/posture correcting means further corrects the desired position and/or posture of the foot based on an posture error of the robot.

10. A system according to any of claims 5 to 9, wherein a compensating total floor reaction force'"'"'s moment for posture stabilization that is to be added to the desired pattern of the total floor reaction force is determined, and the foot rotation amount determining means and/or the foot movement amount determining means determines the foot rotation amount and/or the foot movement amount based on at least the detected actual floor reaction force and the determined compensating total floor reaction force'"'"'s moment for posture stabilization.

11. A system according to claim 10, wherein the compensating total floor reaction force'"'"'s moment for posture stabilization is determined based on an inclination error of the robot.

12. A system according to claim 10 or 11, wherein the foot rotation amount determining means and/or the foot movement amount determining means determines the foot rotation amount and/or the foot movement amount such that the determined compensating total floor reaction force'"'"'s moment for posture stabilization is distributed to each of the legs.

13. A system according to claim 4, further including:

s. gait generating means for generating gait of the robot including at least a motion pattern of the robot including at least the desired position and/or posture of the foot and a desired trajectory pattern of a total floor reaction force acting on the robot;

t. compensating total floor reaction force calculating means for calculating a compensating total floor reaction force for posture stabilization;

u. actual floor reaction force detecting means for detecting an actual floor reaction force acting on the foot; and

v. floor reaction force distributing means for distributing the total floor reaction force of the generated gait and the compensating total floor reaction force;

wherein the correcting means corrects the desired foot position and/or posture based on the distributed total floor reaction force of the generated gait and the compensating total floor reaction force, the detected actual floor reaction force and the calculated floor shape estimation value.

14. A system according to claim 13, wherein the compensating total floor reaction force for posture stabilization is calculated based on an inclination error of the robot.