Legged robot and its control method

• US 8,386,076 B2
• Filed: 09/12/2008
• Issued: 02/26/2013
• Est. Priority Date: 09/12/2007
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Honda, Daisaku, Suga, Keisuke, Tajima, Ryosuke
• Primary Examiner(s): Black, Thomas
• Assistant Examiner(s): LOUIE, WAE LENNY
• Application Number:
  US12/209,444
• Publication Number:
  US 20090069941A1
• Time in Patent Office: 1,628 Days
• Field of Search: 700/258, 700/245, 700/251, 700/253, 700/260, 700/261, 318/568.12, 318/568.16, 180/8.5, 180/8.6
• US Class Current: 700/245
• 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

There is provided a legged robot that performs motion by changing a joint angle, which includes a trajectory generating section to calculate a center-of-gravity trajectory in designated stepping motion from the stepping motion including at least one of walking motion, running motion and stopping motion, and generate a center-of-gravity trajectory by superimposing a designated travel velocity onto a travel velocity of a center of gravity in the calculated center-of-gravity trajectory in stepping motion, and a trajectory updating section to store the generated center-of-gravity trajectory and update all the stored center-of-gravity trajectories so as to be continuous, and a trajectory reproducing section to calculate time-varying data of a target value of the joint angle based on the updated center-of-gravity trajectory, and a joint driving section to rotate a joint of the legged robot based on the calculated time-varying data of a target value of the joint angle.

Claims

1. A legged robot comprising:

trajectory generating means to generate a center-of-gravity trajectory in stepping motion to achieve stable stepping, the stepping motion including at least one of walking motion, running motion, and stopping motion by setting a periodic boundary condition and a given target ZMP to a trinomial equation obtained by discretizing a ZMP equation, and obtain a center-of-gravity velocity in the center-of-gravity trajectory from the generated center-of-gravity trajectory in the stepping motion;

trajectory updating means to determine a velocity condition based on the center-of-gravity velocity obtained by the trajectory generating means and a given travel velocity, and generate a center-of-gravity trajectory to achieve at least one of walking motion, running motion, and stopping motion by setting the velocity condition and the given target ZMP to the trinomial equation;

trajectory reproducing means to calculate time-varying data of a target value of the joint angle based on the center-of-gravity trajectory generated by the trajectory updating means; and

joint driving means to rotate the joint based on the time-varying data of the target value of the joint angle calculated by the trajectory reproducing means.

2. The legged robot according to claim 1, wherein the trajectory generating section generates the center-of-gravity trajectory by acquiring a designated portion of the calculated center-of-gravity trajectory in stepping motion and superimposing the designated travel velocity onto a travel velocity of a center of gravity in the acquired trajectory.

3. The legged robot according to claim 2, wherein the designated portion of the stepping trajectory is a one-step trajectory of the legged robot.

4. The legged robot according to claim 1, wherein each motion included in the stepping motion contains data that includes at least one of a target ZMP trajectory, a period of motion, a sequence of lifting a foot, and a grounding position of a foot tip.

5. The legged robot according to claim 1, wherein the trajectory generating section calculates a center-of-gravity trajectory in stepping motion by solving simultaneous equations established among a matrix containing a coefficient calculated based on a vertical center-of-gravity trajectory, a column of horizontal center-of-gravity trajectory, and a column of target ZMP.

6. The legged robot according to claim 5, wherein the matrix is a matrix containing the coefficient calculated based on the vertical trajectory so that an equation related to a first element in the column of target ZMP involves a last element in the column of center-of-gravity trajectory, and an equation related to a last element in the column of target ZMP involves a first element in the column of center-of-gravity trajectory.

7. The legged robot according to claim 1, wherein the trajectory updating section calculates a center-of-gravity trajectory by solving simultaneous equations established among a tridiagonal matrix containing a coefficient calculated based on a vertical center-of-gravity trajectory, a column of horizontal center-of-gravity trajectory, and a column of distance calculated from a target ZMP and a travel velocity.

8. The legged robot according to claim 1, wherein if a center-of-gravity trajectory stored in the trajectory reproducing section becomes equal to or less than a predetermined time interval, the trajectory reproducing section requests a center-of-gravity trajectory to the trajectory updating section, the trajectory updating section stores a center-of-gravity trajectory of a plurality of number of steps and, if the stored center-of-gravity trajectory becomes equal to or less than a predetermined time interval, the trajectory updating section requests generation of a center-of-gravity trajectory to the trajectory generating section, and if the trajectory generating section receives a request for generation of a center-of-gravity from the trajectory updating section, the trajectory generating section generates a center-of-gravity trajectory in stepping motion.

9. A control method of a legged robot that performs motion by changing a joint angle, comprising:

generating a center-of-gravity trajectory in stepping motion to achieve stable stepping, the stepping motion including at least one of walking motion, running motion, and stopping motion by setting a periodic boundary condition and a given target ZMP to a trinomial equation obtained by discretizing a ZMP equation, and obtaining a center-of-gravity velocity in the center-of-gravity trajectory from the generated center-of-gravity trajectory in the stepping motion;

determining a velocity condition based on generated the center-of-gravity velocity and given travel velocity, and generating a center-of-gravity trajectory to achieve at least one of walking motion, running motion, and stopping motion by setting the velocity condition and the given target ZMP to the trinomial equation;

calculating time-varying data of a target value of the joint angle based on the generated center-of-gravity trajectory; and

rotating the joint based on the calculated time-varying data of the target value of the joint angle.

10. The control method of the legged robot according to claim 9, comprising:

generating the center-of-gravity trajectory by acquiring a designated portion of the calculated center-of-gravity trajectory in stepping motion and superimposing the designated travel velocity onto a travel velocity of a center of gravity in the acquired trajectory.

11. The control method of the legged robot according to claim 10, comprising:

the designated portion of the stepping trajectory is a one-step trajectory of the legged robot.

12. The control method of the legged robot according to claim 9, comprising:

each motion included in the stepping motion contains data that includes at least one of a target ZMP trajectory, a period of motion, a sequence of lifting a foot, and a grounding position of a foot tip.