2PAC: Two Point Attractors for Center Of Mass Trajectories in Multi Contact Scenarios
TimeThursday, 6 December 20185:33pm - 5:59pm
DescriptionSynthesizing motions for legged characters in arbitrary environments is a long-standing problem that has recently received a lot of attention from the computer graphics community.
We tackle this problem with a procedural approach that is generic, fully automatic and independent from motion capture data. The main contribution of this paper is a point-mass-model-based method to synthesize Center Of Mass trajectories. These trajectories are then used to generate the whole-body motion of the character.
The use of a point mass model results in physically inconsistent motions and joint limit violations when mapped back to a fullbody motion. We mitigate these issues through the use of a novel formulation of the kinematic constraints that allows us to generate a quasi-static Center Of Mass trajectory, in a way that is both user-friendly and computationally efficient.
We also show that the quasi-static constraint can be relaxed to generate motions usable for computer animation, at the cost of a moderate violation of the dynamic constraints.
Our method was integrated in our open-source contact planner and tested with different scenarios - some never addressed before- featuring legged characters performing non-gaited motions in cluttered environments. The computational efficiency of our trajectory generation algorithm (under one ms to compute one second of trajectory) enables us to synthesize motions in a few seconds, one order of magnitude faster than state-of-the-art methods. Although our method is empirically able to synthesize collision-free motions, the formal handling of environmental constraints is not part of the proposed method, and left for future work.