Method for generating a motion of a human type link system

• US 7,136,722 B2
• Filed: 02/10/2003
• Issued: 11/14/2006
• Est. Priority Date: 02/12/2002
• Status: Expired due to Fees

• Current Assignee: University of Tokyo
• Original Assignee: University of Tokyo
• Inventors: Tange, Manabu, Yamane, Katsu, Nakamura, Yoshihiko
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): Marc, McDieunel
• Application Number:
  US10/360,873
• Publication Number:
  US 20030220714A1
• Time in Patent Office: 1,373 Days
• Field of Search: 700/245, 700257-260, 700263-264, 318/568.1, 318/568.11, 318/568.16, 318/568.53, 318/568.24, 901/6, 901/9, 901/29, 901/34, 200/341
• US Class Current: 700/245
• CPC Class Codes: B25J 9/1633 compliant, force, torque control, e.g. combined with position control
• CPC Class Codes: G05B 2219/39323 Force and motion control
• CPC Class Codes: G05B 2219/40316 Simulation of human-like robot joint, restricted 3-D motion
• CPC Class Codes: G05B 2219/40517 Constraint motion planning, variational dynamic programming
• CPC Class Codes: G06T 13/40 of characters, e.g. humans, animals or virtual beings

Abstract

A human-type link system, such as a humanoid robot having a dynamically feasible motion of the link system that is generated when a reference joint acceleration that is only calculated from a kinematical constraint condition is determined not feasible by an evaluation of external force computed based on an inverse dynamics calculation, or is generated by calculating from a dynamic constraint condition and a kinematical constraint condition simultaneously, the dynamic constraint condition is formulated by using an actuation space inverse inertial matrix that represents the relation of force acting on the link system and the acceleration of the link system caused by the force.

Claims

1. A method for generating a motion in a link system of a mechanical model of human or humanoid motion or a virtual model of human or humanoid motion, comprising,

(a) a step of calculating a reference joint acceleration of the link system only from a kinematic constraint condition;

(b) a step of calculating external force that is needed for generating the reference joint acceleration, by inverse dynamic calculation from the reference joint acceleration derived from step (a);

(c) a step of evaluating a feasibility of the reference joint acceleration, by checking whether the external force calculated in step (b) is valid as a contact force;

(d) a step of employing directly the reference joint acceleration as a joint acceleration of the link system when the external force is determined to be valid as a reaction force in step (c);

(e) a step of recalculating, when the external force is determined to be invalid as a reaction force in step (c), the external force to derive a new valid value of the external force, then, executing the steps (a) to (c) to add a new constraint condition so that the value of the external force substitutes to the new valid value;

wherein steps (a) to (e) are exerted by a computer; and

the new valid value of the external force is calculated in step (e) by;

setting the external force zero, when the vertical direction force has direction to pull the link;

setting the nearest point in a convex hull of a contact region of the link system as a new pressure center point, when a pressure center point of the external force exists out of the convex hull;

setting a maximum static frictional force as a new frictional force by the external force, when a frictional force by the external force is larger than the maximum static frictional allowed in the same direction as the frictional force.

2. The method of claim 1, wherein the external force is computed based on an inverse dynamics calculation.

6. A robot having a link system of a mechanical model of human or humanoid motion, the robot comprising:

a motion generating engine, wherein the engine generates motion according to the method of claim 1.

7. The robot of claim 6, wherein the engine generates dynamically feasible motion by determining a value of a dynamic constraint condition and determining a value of a kinematical constraint condition.

8. The robot of claim 7, wherein the dynamic constraint condition is formulated by using an actuation space inverse inertial matrix.

9. The robot of claim 8, wherein the actuation space inverse inertial matrix represents the relationship of the force acting on the link system and the acceleration of the link system caused by the force.

3. A method for generating a motion in a link system of a mechanical model of human or humanoid motion or a virtual model of human or humanoid motion, comprising,

a. a step of calculating an actuation space inverse inertial matrix which represents a relation between contact force acted on a reference link of the link system and a link acceleration of the reference link;

b. a step of calculating a matrix which represents a relation between a joint acceleration and an acceleration of a constraint point when a contact is not taken into account;

c. a step of calculating contact force from a contact point assuming a spring and a dumper exists in the contact point;

d. a step of deriving, using two matrices calculated at step (a) and step (b) and the contact force calculated at step (c), an equation which represents a relation of a joint acceleration and a link acceleration of a link given its trajectory and a link constrained at its absolute position;

e. a step of resolving simultaneous equation of the equation in step (d) and equations of another dynamic constraint condition to derive the joint acceleration; and

f. a step of determining joint angle and joint velocity from integral calculation of the joint acceleration which is derived in step (e);

wherein steps (a) to (f) are exerted by a computer.

4. The method of claim 3 wherein the another dynamic constraint condition is formulated by using an actuation space inverse inertial matrix.

5. The method of claim 4, wherein the actuation space inverse inertial matrix represents a relationship of a force acting on the link system and an acceleration of the link system caused by the force.