Abstract

Under-actuated bipedal walking robots are an active area of research. Previously, Sangwan and Agrawal (2007) have presented a mechanical design methodology for under-actuated bipeds based on placing center-of-mass of the legs at the hip joint that renders dynamics of a class of planar bipedal walking robots differentially flat. Once this class of under-actuated bipeds is proven to be differentially flat, one can analytically write down a feasible parametrized family of trajectories. Proving flatness results for an n-dof bipedal robot does not guarantee the existence of reasonable walking solutions satisfying the motion constraints. This work demonstrates planning and tracking control of feasible walking trajectories satisfying motion constraints for a higher degree-of-freedom four-link biped with a knee joint in each leg.