RHex is a hexapod with compliant legs and only six actuated degrees of freedom. Its ability to traverse highly fractured and unstable terrain, as well ascend and descend a particular flight of stairs has already been documented. In this paper, we describe an open loop controller that enables our small robot (Length: 51 cm, Width: 20 cm, Height: 12.7 cm. Leg length: 16 cm), to reliably climb a wide range of regular, full-size stairs with no operator input during stair climbing. Experimental data of energy efficiency in the form of specific resistance during stair climbing is given. The results presented in this paper are based on a new half circle leg design that implements a passive, effective leg length change.
E. Z. Moore, D. Campbell, Felix Grimminger, Martin