Articulated Swimming Creatures

Contribution:
Evaluation:
Reproducibility:
Improvements:

Contribution: The paper presents a simulation environment for articulated virtual creatures swimming in a fluid environment, and an optimization method to find viable swimming "gaits" for any given creature morphology. The simulator uses a voxelization approach along with standard Navier-Stokes equations to simulate the interaction between a creature and its fluid environment. Covariance Matrix Adaptation is then used to optimize control of a given creature as it swims. The results tend to resemble real-world creature movement due to the accurate simulation and effective objective function used in optimization.

Evaluation: The system is evaluated by testing it on models of several different real-world swimming creatures, including a fish, eel, frog and manta ray. Success is measured as how well the resulting motion approximates real motion observed in nature, in addition to how well the creatures can follow a path. Finally the same test is run on a creature morphology that does not exist in nature, with subjective observations on plausibility of the motion made instead of comparison to (non-existent) real-world motion. They also ran the same set of experiments using a much simpler fluid solver and compared the results.

Reproducible: The paper is reproducible due to the high level of detail presented on both how their simulator works and how their optimization routine functions. Almost all of the equations used in simulation are presented. The optimization is not presented in quite as much detail, but the gaps should be fairly easy to fill in by reading about the Covariance Matrix Adaptation method.

Improvement: I have no complaints about this paper. It is very well-organized, well-written and extremely thorough, making it relatively easy to understand the concepts presented within. It is also very thorough in its evaluation and testing of the system.

-- Main.cdoran - 01 Dec 2011

Contribution: The authors attempt to animate swimming creatures while seeking some measure of physical accuracy. To do so, they create a variety of virtual articulated creatures (both based on real animals and purely invented) and optimize control strategies while also simulating fluid dynamics.

Evaluation: Their ambitious goal is hard to evaluate from the onset, and sure enough their results are of "oh, look how pretty it looks" variety. Some of the remarks do make sense, like the fact that the opmitized control strategies ressemble those of real creatures, so in that sense it seems obvious that their approach is reasonable.

Reproducibility: As usual with these papers, the equations seem to be worked out in sufficient details. Not too much detail is given on the experiments, and in particular not too much is mentioned on how the optimization was carried out, which means it could have been either extremely easy or extremely hard.

Improvements: They mention themselves that the voxelization approach is not ideal, and can be improved upon. But all in all, they seem to have succeeded in their goal (which is why their suggested future work doesn't really make sense, swimming at the surface of the water seems like quite a different problem).

-- Main.ginestra - 01 Dec 2011

-- MichielVanDePanne - 27 Nov 2011