Optimizing Walking Controllers

Contribution:
Evaluation:
Reproducibility:
Improvements:

-- MichielVanDePanne - 24 Nov 2011

Contribution
The study describes a controller for physically simulated characters. The goal of the study is to create an automatic method to define controllers for 3D human-like characters to walk more like humans. Their method does not use any motion capture data nor any reference trajectories. It also produces reasonable results for characters with different mass distributions. The authors achieve these results by parametrizing the controller, and optimizing those parameters with respect to a high-level objective function. Previous studies have used optimization on lower dimensional spaces, but 3D walking is a difficult problem since it involves high-dimensional state space, nonlinear dynamics, and a discontinuous search space due to ground contact. Hence, One of their main contributions is, given a carefully a chosen objective function and a good control parameterization, they show that their method can work for 3D human-like walking.

Evaluation
The results are evaluated based on the computed motions, for several iterations. They also compare their output animations to the related studies, such as their own implementation of SIMBICON, as well as to the mocap data. Hence, their result is compared visually

Reproducibility
The method being implemented can be reproduced since all the functions and the constraints related to optimization, i.e. objective function, gait, head, and body constraints, etc. are given. Moreover, the simulation parameters, and the initial simulation state, as well as the PD controller parameters are also given.

Improvements
As the authors suggest, more sophisticated controllers and objective functions could be designed and tested with the framefork, since the objective function and the optimizer are independent of the control parameters. Such further experiments would have supported the authors' claim that such optimization methods could be utilized for high-dimensional problem of human motion synthesis and control. In terms of paper writing, the sections are well-organized and the flow of the paper is easy to follow.

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-- Main.ooguz - 24 Nov 2011