Walking robots, passive dynamics, human walking, hopping, brachiation models, rowing mechanics, collision costs in locomotion.

Walking is in some sense non-holonomic, adding to the small list of non-holonomic mechanisms such as rolling and skating that might contribute to passive dynamic stability without dissipation.

The phrase 'rigid body collisions' is an oxymoron; collisional forces depend on deformation. Nonetheless, Chatterjee - now a former student of mine, and I worked out some of the basics of this classical subject.

In my lab, Papadopoulos, Hand, and more recently Schwabb, have worked out interesting details about the passive stability of a moving bicycle. A bit here on pedaling mechanics as well.

With help from the three Jims - Rice, Dieterich and Papadopoulos, as well as former students Horowitz and Goyal, we worked out various things about how solids can and might slide against each other. About fracture, why K?

Sailing downwind, disks and tops, and various other rants and odds and ends.