Gait Generation of a 10-Degree-of-Freedom Humanoid Robot on Deformable Terrain Based on Spherical Inverted Pendulum Model

Abstract

Gait generation of a humanoid robot on a deformable terrain is a complex problem as the foot and terrain interaction and terrain deformation have to be included in the dynamics. To simplify the dynamics of walk on deformable terrain, we used a spherical inverted pendulum (SIP) to represent the single support phase, in which the effect of terrain deformation is represented by a spring and damper contact model. The impact model for leg transition is derived from angular momentum conservation. In order to minimize the energy loss due to impact, the double support phase is modeled as a suspended pendulum. Based on the motion of the SIP model, the hip and leg trajectories of a 10-degree-of-freedom (DOF) humanoid robot are generated. The joint trajectories of the robot are obtained from inverse kinematics. The motion of the center of mass is analyzed by inverse dynamics of a floating-base robot. The proposed gait generation method has been experimentally validated using a Kondo KHR-3HV humanoid robot on deformable terrain. The results show that the humanoid can effectively track the trajectories of the SIP model.