Control Through Passive Elements

Problem
There are several notable examples of control through passive elements in the robotics literature. McGeer's passively stable walkers were legged mechanisms with knees that walked down slopes without computer control. Raibert took advantage of the passive bouncing behavior of a mass/spring system when he designed his one-legged robot with a passive air spring.

Humans probably also use passive elements to control many of their motions. For example, the swing through of the idle leg in walking is largely passive, much as it was with McGeer's walker. Other examples of passive control have yet to be fully understood.

The moment of inertia of the human body in a layout position indicates that it should be impossible for a person to perform a layout somersault without beginning to tumble out of control. But ski jumpers routinely perform several rotations in a layout position. A thesis by Rob Playter (MIT AI Lab) demonstrated that the somersaulting motion may be stabilized by passive elements that act like springs at the shoulder joints. For this project you should implement a simulated figure (rigid body with shoulder joints) in a commercially available simulation package. Use your simulation to verify his results by finding spring constants that allow the figure to perform stable somersaults in a layout position.

Useful knowledge: You'll want to display the results of your simulation graphically so knowledge of inventor (or a desire to learn) would be useful. The simulation package has a good manual but you'll need some understanding of physics/dynamics.