Computing Reviews
Today's Issue Hot Topics Search Browse Recommended My Account Log In
Review Help
Search
Multi-contact locomotion using a contact graph with feasibility predictors
Kang C., Lee S. ACM Transactions on Graphics (TOG)36 (2):1-14,2017.Type:Article
Date Reviewed: Aug 10 2017

A method to compose multi-contact locomotion for characters in complex environments is proposed in this paper. This is accomplished through a two-step process, where existing motion data is first pre-processed into a contact graph, after which an online process can generate the feasible motion for the environment.

During the pre-processing step, the original motion data is segmented into a series of contact motion clips, which describe the various contact states of the characters (for example, whether the hands and feet are in contact or not). Each clip is further annotated by a contact space, which uses motion deformation along with feasibility constraints in order to estimate the exact space that the contact points will make. Finally, an occupancy estimator is created for the character, given its sequence of contact spaces. Such estimators allow the method during the online process to quickly estimate whether a contact will result in a collision with the environment.

During the online process, the environment is processed into a signed distance field (SDF). Then, the method performs contact planning, which uses covariance matrix adaption evolution strategy (CMA-ES) over the SDF in order to produce an optimal set of contact points for the end-effectors. Once this sequence of contact points is computed, the method uses Laplacian motion deformation (from the pre-processing phase) to find the full body motion in an iterative process, during which at each step the joint that has the largest penetrating collision is fixed. Finally, inverse kinematics is used to obtain the actual movement of the character once a collision-free path has been obtained.

The experiments show that the method successfully adapted multi-contact locomotion to a variety of complex environments, some of which included some difficult narrow passages, which are common failure points of local planners. Furthermore, the experiments indicate that this method reduces the amount of time the local planner spends verifying that the solution is valid (that is, collision-free and kinematically feasible). Finally, due to the optimization processes used in the method (Levenberg-Marquardt, CMA-ES), the contact points chosen by the method for end-effector placements should be optimal, which in turn allow for smooth motion generation.

Some immediate future work that could be done would be to apply the method to other types of motions. It would also be interesting to see if this work could be extended to work with multiple characters, for instance, two characters carrying an object together, or several characters performing maneuvers (that is, standing on a pyramid formation) with one another. Currently, the method does not take the physical feasibility of the motion into account. Such dynamic constraints could be factored into the contact space, and be used to improve the success rate of the local planner in finding physically feasible solutions.

This work could also be considered for use in robotics applications, such as grasp planning (which similarly relies on contact planning), where the local planner often takes the majority of the processing time. In such situations, the notion of the contact graph and occupancy estimator could improve both the speed and success rate of the local planner.

Reviewers:  Mubbasir KapadiaAndrew Kimmel Review #: CR145477 (1710-0688)
Bookmark and Share
 
Animation (I.3.7 ... )
 
Would you recommend this review?
yes
no
Other reviews under "Animation": Date
Making them move
Badler N., Barsky B., Zeltzer D., Morgan Kaufmann Publishers Inc., San Francisco, CA, 1991. Type: Book (9781558601062)
Jul 1 1992
Computer animation primer
Fox D., Waite M., McGraw-Hill, Inc., New York, NY, 1984. Type: Book (9789780070217423)
Mar 1 1985
High speed animation and simulation for microcomputers
Adams L., TAB Books, Blue Ridge Summit, PA, 1987. Type: Book (9789780830628599)
Aug 1 1988
more...

E-Mail This Printer-Friendly
Send Your Comments
Contact Us
Reproduction in whole or in part without permission is prohibited.   Copyright 1999-2024 ThinkLoud®
Terms of Use
| Privacy Policy