FORCE CONTROL OF THE REDUNDANT LEG OF A BIPED ROBOT TO PRODUCE LARGE INERTIAL EFFECTS FOR CROSSING OBSTACLES

Abstract

This paper proposes an energy control method for dynamic obstacle crossing by a planar biped. This approach was tested in a simulation where it was found to enable the biped robot to cross obstacles of different heights, due to inertial forces, by leaning with the front foot on the obstacles. The propulsion energy of the system is produced by the rear leg, which is endowed with four actuated degrees-of-freedom (hip, knee, ankle, toes), and is controlled by force control with four degrees-of-freedom in the non-singular case, and three degrees-of-freedom in the singular case. This paper identifies ten geometric, energetic and servo-control parameters necessary for dynamic obstacle crossing. The methodology presented allowed the dynamic crossing of an obstacle up to 20 cm high, at which point the joint torque limit for the propelling ankle was reached.