Generic model generation considerations

[iandanforth]

Todo

• Find out of MuJoCo supports cycles, e.g. 4-bar linkage.
• Read up on tracery to see if a tracery grammar would be useful to describe the creature shapes

Description

This ticket is to collect throughts on a high-level API which might be useful for not only replicating existing mujoco models but creating arbitrary creatures, or evolving existing ones.

Body plans

We want to be able to support bodies where are basically biological in shape. Mechanical structures should probably be ruled out.

A general constraint is the hierarchical format of XML. This makes cyclic relationships hard to model.

We also want to be able to describe bodies in a way that is useful to genetic algorithms.