Humanoid robots walking on grass, sands and rocks

Up to now humanoid robots have been designed primarily for walking on flat surfaces. In the future, humanoid robots are required to replace human beings to operate in natural or damaged man-engineered environments. In such environments, the robots may have to walk on rough surfaces such as grass, sands or rocks, which all impose great challenges to the stability of biped locomotion due to uncertainties and deformations of these surfaces. We investigate how humanoid robots can walk on these surfaces, using the Hubo 2+humanoid robot as the target of study. We will first introduce the overall structure of Hubo 2+, and model the deformation characteristics these surfaces. Then new walking patterns, a "step-over" gait and a ski-type gait, are proposed as a global approach to maintain stability while compliant motion is used to solve the robust foot-holding problem. Simulation and experimental results are presented to verify the new approaches.