Difference: ArticulatedSwimming (7 vs. 8)

Revision 82011-12-01 - BenHumberston

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Articulated Swimming Creatures

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Improvements: Even though they did state their main limitation in the paper - the parameterization of the joint space, they didn't really elaborate on how important that is. As I understand, if we presume that the gait is parameterized by one sine function, the motion is 'static', i.e. the optimization cannot take into account any obstacles, other streams in the fluid, etc. - basically, everything that may make the motion uneven.

-- MikhailBessmeltsev - 01 Dec 2011

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Contribution: This paper presents a method for optizing the swimming performance of a variety of creatures in a virtual aquatic environment that simulates the two-way force couping between the fluid and rigid segments of the creatures. Their objective function They utilize Covariance Matrix Adaptation (CMA) for their optimization stage, in addition to two heuristics used to accelerate convergence to a minimum for the objective function.

Evaluation: The authors describe the time necessary to optimize the creature stroke (hours) and to simulate each frame of the fluid environment (seconds) for a variety of creature morphologies. They present qualitative analysis of the resulting swimming styles compared to observed styles of real creatures. Additionally, they qualitatively compare the swimming styles of the creatures using either the sophisticated Navier-Stokes implementation or a simple normal-force fluid model. They particularly note that the computationally expensive NS model is required for creatures that swim by jet propulsion.

Reproducibility: The authors provide sufficient details on their PD controllers and objective functions. The coupled solid-fluid environment is able to be reproduced by referencing the original source paper for the technique. Given the relatively straightforward objective of the paper and the use of techniques described in earlier work in fluid simulation and optimization, the paper certainly provides a reproducible basis.

Improvements:

Clarification: How do the authors choose the period and phase offset values for the reference trajectories sine functions? Does the phase offset vary per degree of freedom for creatures beside the accordion?
Why are only 2 swim cycles used per optimization iteration? Is it possible that irregularities or problems would result for a creature after >2 cycles, especially given the dynamic forces given from the fluid simulation?

-- BenHumberston - 01 Dec 2011

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-- MichielVanDePanne - 27 Nov 2011

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