Optimizing ergonomic movement of a virtual dummy

• US 20040263531A1
• Filed: 04/27/2004
• Published: 12/30/2004
• Est. Priority Date: 04/28/2003
• Status: Active Grant

• Current Assignee: Safran Aircraft Engine Company
• Original Assignee: Snecma Moteurs
• Inventors: Chedmail, Patrick, Maille, Bruno, Ramstein, Edouard
• Granted Patent: US 7,336,281 B2
• Time in Patent Office: Days
• US Class Current: 345/619
• CPC Class Codes: G05B 2219/31066 Virtual assembly disassembly planning
• CPC Class Codes: G05B 2219/40433 Distributed, trajectory planning for each virtual arm
• CPC Class Codes: G06T 13/40 of characters, e.g. humans, animals or virtual beings
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

The invention relates to a multi-agent method and system for moving a virtual dummy in a virtual environment, the dummy being defined by an overall position and by a plurality of degrees of freedom for joints. The method comprises:

a contribution from an attraction agent acting on the plurality of degrees of freedom of the joints of the dummy to move the dummy towards the target; and

a contribution from an avoider agent acting on the overall position of the dummy as a function of parameters defining the environment in order to avoid collisions between the dummy and said environment.

The method further comprises a contribution from an ergonomy agent acting on the plurality of degrees of freedom of the joints of the dummy in order to correct the posture of the dummy automatically while it is moving towards the target.

Claims

1. A multi-agent method for moving a virtual dummy in a virtual environment, the dummy being defined by an overall position and by a plurality of degrees of freedom for joints, the method comprising:

a step of moving the dummy towards a target by means of an attraction agent acting on the plurality of degrees of freedom of the joints of the dummy; and

a step of avoiding collisions between the dummy and the environment by means of an avoider agent acting on the overall position of the dummy as a function of parameters defining said environment;

the method further comprising a step of automatically correcting the posture of the dummy during its movement towards the target by means of an ergonomy agent acting on the plurality of degrees of freedom for the joints of the dummy, and comprising the following steps;

determining a posture score vector depending on the degrees of freedom of the joints of the dummy;

normalizing said posture score vector in order to form a normalized posture score vector;

weighting said normalized posture score vector in order to form a weighted posture score vector; and

inverting the sign of said weighted posture score vector so as to determine the contribution of the ergonomy agent.

2. A method according to claim 1, further including a step of overall movement towards the target by means of an attraction agent acting on the overall position of the dummy.

3. A method according to claim 1, wherein, for each degree of freedom of the joints of the dummy, a score of zero is allocated to an open interval defined about the position in which the algebraic score changes sign, said interval having a range equal to one joint movement pitch predefined for the degree of freedom under consideration.

4. A method according to claim 1, wherein the normalization step is implemented by dividing all of the components of the posture score vector by the maximum absolute value of said components.

5. A method according to claim 1, wherein the weighting step is implemented by multiplying each component of the normalized posture score vector by the joint movement pitch predefined depending on the type of joint.

6. A method according to claim 5, wherein the joint movement pitch is constant for all of the joints.

7. A method according to claim 5, wherein the joint movement pitch is an angle lying in the range 0.001 rad to 0.1 rad.

8. A method according to claim 1, wherein the step of determining the posture score vector is implemented by transforming a RULA type posture criterion into an algebraic criterion depending on whether each posture score is implemented in the positive direction or the negative direction of the joint.

9. A method according to claim 1, further including an additional step of avoiding collisions between the dummy and the environment by means of an avoider agent acting on the plurality of degrees of freedom of the joints of the dummy as a function of parameters defining said environment.

10. A method according to claim 1, further including a step of an operator moving the dummy in real time by means of at least one operator agent acting on the overall position and/or on the plurality of degrees of freedom of the joints of the dummy.

11. A method according to claim 1, wherein the attraction agents, the avoider agents, the ergonomy agent, and the operator agents interact in a hierarchical manner through shared digital data defining the dummy and its environment.

12. A method according to claim 11, wherein the attraction agents, the avoider agents, the ergonomy agent, and the operator agents are organized hierarchically by giving each of them an activity interval that is steady throughout the movement of the dummy.

13. A method according to claim 12, wherein the activity interval of the avoider agents is the shortest and that of the ergonomy agent is the longest.

14. A method according to claim 12, wherein the activity interval of the avoider agents is an integer in the range 1 or 2, the activity interval of the attraction agents is an integer in the range 2 to 4, the activity interval of the ergonomy agent is an integer in the range 5 to 15, and the activity interval of the operator agents is an integer in the range 2 to 4.

22. A computer program, designed to implement the method according to claim 1 when executed on a computer.

15. A multi-agent system for moving a virtual dummy in a virtual environment, the dummy being defined by an overall position and by a plurality of degrees of freedom for joints, the system comprising:

an attraction agent for acting on the plurality of degrees of freedom of the joints of the dummy to move the dummy towards a target; and

an avoider agent for acting on the overall position of the dummy as a function of parameters defining the environment so as to avoid collisions between the dummy and said environment;

the system further comprising an ergonomy agent for acting on the plurality of degrees of freedom of the joints of the dummy in order to correct the posture of the dummy automatically during its movement towards the target, the ergonomy agent comprising a vector whose components are defined by the negative of the weighted posture scores of the joints.

16. A system according to claim 15, wherein the posture scores are based on an algebraic criterion of a RULA type posture system.

17. A system according to claim 15, wherein each degree of freedom of the plurality of degrees of freedom of the joint is defined by an angular movement pitch lying in the range 0.001 rad to 0.1 rad.

18. A system according to claim 15, further comprising an attraction agent for acting on the overall position of the dummy in order to move it in overall manner towards the target.

19. A system according to claim 15, further comprising an avoider agent for acting on the plurality of degrees of freedom of the joints of the dummy as a function of parameters defining the environment so as to avoid collisions between the dummy and said environment.

20. A system according to claim 15, further comprising at least one operator agent for acting on the overall position and/or on the plurality of degrees of freedom of the joints of the dummy in order to enable an operator to act in real time on the movement of the dummy.

21. A system according to claim 15, wherein the attraction agents, the avoider agents, the ergonomy agent, and the operator agents are designed to interact in hierarchical manner through shared digital data defining the dummy and its environment.