Wanting to build simple but interesting looking robots, chose an interesting articulated wheel: the Theo Jansen mechanism.
All robots were programmatically generated, composed entirely of individual rigid body physics parts (everything you see) with relative mass, driven only by their motors' torque (angular/rotation force), nothing else.
No manual keyframes; no animation bones or inverse kinematics; only pure physics consequences from simple motor logic, resulting movements are natural behaviours.