Control system for legged mobile robot

• US 5,349,277 A
• Filed: 03/11/1993
• Issued: 09/20/1994
• Est. Priority Date: 03/12/1992
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Takahashi, Hideo, Yoshino, Ryutaro
• Primary Examiner(s): Ip, Paul
• Application Number:
  US08/029,895
• Time in Patent Office: 558 Days
• Field of Search: 318/560-646, 901/1, 901/3, 901/5, 901/7, 901/9, 901/12, 901/13, 901/15-23, 901/48, 395/80-99, 180/8.1-8.7
• US Class Current: 318/568.12
• 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 system for controlling locomotion of a biped walking robot having a body and two articulated legs each connected to the body through a hip joint and having a knee joint and an ankle joint adjacent to a foot portion. The individual joints are provided with servo motors and target angle data is provided to the servo motor in time series at a predetermined interval. The actual inclination angle of the body is detected and is then compared with upper and lower limits. If the detected value is found to be out of either of the limits, a control value of the servo motor for the hip joint of the free leg lifted off of the ground is corrected in such a manner that the free leg lands forward if the robot tilts forward, for example. A control value for the supporting leg is also corrected. Moreover, the ankle joint'"'"'s angle is detected with respect to the direction of gravity and the control value of the ankle joint is corrected in response to the detected value. In addition, when the body'"'"'s inclination angle exceeds either of the limits, the time interval is changed such that the robot'"'"' s leg lands at a time earlier or later than the scheduled time.

Claims

1. A system for controlling locomotion of a biped walking robot having a body and two articulated legs each connected to the body through a hip joint and each having at least an ankle joint, comprising:

servo motor means provided at individual joints of the robot;

first means for establishing a walking pattern of the robot in terms of angles with respect to the direction of gravity;

second means for determining a target angle of each joint from the established walking pattern;

third means for detecting an actual angle of each joint;

fourth means for determining a basic control amount for each joint in response to a deviation between the target angle and the detected actual angle of each joint;

fifth means for detecting a differential of n-th order of an actual inclination angle of the body with respect to the direction of gravity;

sixth means for determining a first control correction amount for at least one of the hip joint and the ankle leg which supports the robot'"'"'s weight in response to the detected differential of n-th order of the actual inclination angle of the body; and

control means for correcting the basic control amount by the first control correction amount to determine a control value for each servo motor means and for providing the determined control value to the servo motor means.

2. A system according to claim 1, wherein said sixth means determines the first control correction amount by multiplying the detected differential of n-th order or the actual inclination of the body by a gain.

3. A system according to claim 1, wherein said sixth means determines the first control correction amount by multiplying the detected inclination angle and angular velocity of the body by a first gain and a second gain.

4. A system according to claim 1, further including;

seventh means for detecting at least one of acting on the ankle joint to determine a second control correction amount by multiplying the detected moment and said control means corrects the control value for the ankle joint by the second control correction amount.

5. A system for controlling locomotion of a biped walking robot having a body and two articulated legs each connected to the body through a hip joint and each having at least an ankle joint comprising:

servo motor means provided at the individual joints of the robot;

first means for establishing a walking pattern in terms of angles with respect to the direction of

second means for determining a target angle of each joint from the established walking pattern;

third means for detecting an actual angle of each joint;

fourth means for determining a basic control amount for each joint in response to a deviation between the target angle and the detected actual angle of each joint;

fifth means for detecting an angle of the ankle joint of a supporting leg which lands on the ground with respect to the direction of gravity; and

said second means correcting the target angle for the ankle joint of the supporting leg in response to the detected angle.

6. A system for controlling locomotion of a biped walking robot having a body and two articulated legs each connected to the body through a hip joint and each having an ankle joint, comprising:

servo motor means provided at the individual joints of the robot;

first means for establishing a walking pattern of the robot in terms of angles with respect to the direction of gravity;

second means for determining a target angle of each from the established walking pattern;

third means for detecting an actual angle of each

fourth means for determining a basic control amount for each joint in response to a deviation between the target angle and the detected actual angle of each joint;

fifth means for detecting a differential of n-th order of an actual inclination angle of the body with respect to the direction of gravity;

sixth means for determining a first control correction amount for at least one of the hip joint and the ankle joint of a leg which supports the robot'"'"'s weight in response to the detected differential of n-th order of the actual inclination angle of the body; and

seventh means for determining a second control correction amount of at least one of the hip joint and an ankle joint of a free leg lifted off the ground in response to the detected differential of n-th order of the actual inclination angle of the body; and

control means for correcting the basic control amount by the first and the second control correction amounts to determine a control value for each servo motor means and for providing the determined control value to the servo motor means.

7. A system according to claim 6, wherein said seventh means compares the detected differential of n-th order of the actual inclination angle of the body with a reference value and determines the second control correction amount in response to the comparison result.

8. A system according to claim 6, wherein said seventh means holds the second control correction amount over a period during which the free leg is landed and then decreases the second control correction amount with respect to time.

9. A system according to claim 6, wherein the joints are assigned priority in the order of the hip joint of the supporting leg, the ankle joint of the supporting leg and the hip joint of the free leg, and said control means determines the control value at least partially following the order.

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

eighth means for detecting an angle of the ankle joint of the supporting leg with respect to the direction of gravity; and

said second means corrects the target angle of the ankle joint in response to the detected angle.

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

ninth means for detecting at least one of moment and force acting on the supporting leg to determine a third control correction amount; and

said control means corrects the control value for the ankle joint of the supporting leg by the third control correction amount.

12. A system for controlling locomotion of a legged walking robot having a body and a plurality of legs connected to the body, including:

servo motor means provided at individual joints of the robot; and

control means for providing a control value in time series at a predetermined interval in accordance with a preestablished walking data to each servo motor means such that the servomotor means drives the associated joint to a target angle;

wherein the improvement comprises;

first means for measuring differential of n-th order of an actual inclination angle of the body with respect to time to detect a posture of the robot; and

said control means changing the predetermined interval when the detected posture is determined to be out of a predetermined posture such that the robot'"'"'s leg lands at a time other than a scheduled time.

13. A system according to claim 12, wherein said first means compares the measured value with a reference value, and determines if the posture is out of the predetermined posture.

14. A system according to claim 13, wherein the reference value is the robot body'"'"'s inclination angle and angular velocity at which the robot is able to keep its posture stable.

15. A system for controlling locomotion of a biped robot having a body and two articulated legs each connected to the body through a hip joint and each having an ankle joint, comprising:

servo motor means provided at the individual joints of the robot;

first means for establishing a walking in terms of angles with respect to the direction of

second means for determining a target angle of each joint from the established walking pattern;

third means for detecting an actual angle of each joint;

fourth means for determining a basic control amount for each joint in response to a deviation between the target detected actual angle of each joint;

fifth means for detecting a differential of n-th order of an actual inclination angle of the body with direction of gravity;

sixth means for determining a first control correction amount for at least one of the hip joint and the ankle joint of a leg which supports the robot'"'"'s weight in response to the detected differential of n-th order of the actual inclination angle;

control means for correcting the basic control amount by the first control correction amount to determine a control value in time series at a predetermined interval for each servo motor means and for providing the determined control value to the servo motor means concerned; and

seventh means for detecting a posture of the robot; and

said control means changing the predetermined interval when the detected posture is determined to be out of a predetermined posture.

16. A system for controlling locomotion of a biped walking robot having a body and two articulated legs each connected to the body through a hip joint and each having an ankle joint, comprising:

servo motor means provided at the individual joints of the robot;

first means for establishing a walking pattern of the robot in terms of absolute angles;

second means for determining a target angle of each joint from the established walking pattern;

third means for detecting an actual angle of each joint;

fourth means for determining a basic control amount for each joint in response to a deviation between the target angle and the detected actual angle of each joint;

fifth means for detecting a differential of n-th order of an actual inclination angle of the body with respect to the direction of gravity;

sixth means for determining a first control correction amount for at least one of the hip joint and the ankle joint and the ankle joint of a leg which supports the robot'"'"'s weight in response to the detected differential of n-th order of the actual inclination angle;

seventh means for determining a second control correction amount of at least one of the hip joint and an ankle free leg lifted off of the ground in response to the detected differential of n-th order of the actual inclination angle;

control means for correcting the basic control amount first and the second control correction amounts to determine a control value for each servo motor means and for providing the determined control value to the servo motor means;

eighth means for detecting an posture of the robot; and

said control means changing the predetermined interval when the detected posture is determined to be out of a predetermined posture such that the robot'"'"'s leg lands at a time other than a scheduled time.

17. A controller of a servo motor for joints of a biped walking robot having a body and two articulated legs, each connected to the body through a hip joint and each having at least an ankle joint, comprising:

a first control loop for determining a velocity command to be applied to the servo motor by obtaining a deviation between a target joint, determined from a walking pattern established in terms of an angle with respect to the direction of gravity, and an actual joint and multiplying it by a gain;

a second control loop provided at an inner side of the first control loop for determining a second velocity command to be added to the first velocity command by detecting at least one of an actual inclination angle or an actual inclination angular velocity of the body with respect to the direction of gravity and by multiplying the actual inclination angle or the actual inclination angle velocity it by a second gain; and

control means for determining a control command to the servo motor from the first and second velocity commands.

18. A controller according to claim 17, further including:

a third control loop provided at the inner side of the first control loop for determining a third velocity command to be added to the first velocity command by detecting at least one of an actual inclination angle and an actual inclination angular velocity of the body with respect to the direction of gravity to obtain a difference from a reference value and by multiplying the difference by a second gain; and

said control means determines the control command to the servo motor from the first, second and third velocity commands.

19. A controller according to claim 17, further including:

a fourth control loop provided at the inner side of the control loop for determining a fourth velocity command to be added to the first and second velocity commands by detecting at least one of moment and force acting on at least one among the joints of the robot; and

said control means determines the control command to the servo motor from the first, second and fourth velocity commands.

20. A controller according to claim 17, further including:

detecting means for detecting an actual angle of an ankle joint with respect to the direction of gravity; and

said first control loop corrects the target angle by the detected actual angle.