Arbitrary biped robot foot gaiting based on variate COM height

In this paper, we proposes an approach to generate arbitrary quasi-natural foot gait for the walking biped robot with variate COM height preview control. The arbitrary foot gait planning is generated by zero moment point (ZMP) mapping method and a curve with certain radius. In order to walk smoothly in turning gait, the walking pattern is designed in variate height COM motion. However, this method consumes more time to generate trajectory based on conventional preview control. To reduce time consumption, preview control with particular design of COM height trajectory is proposed. Furthermore, the dynamic model is investigated considering the contact force applied on the system. By using the full body dynamic model, the force control architecture is developed, which is comprised of a local joint controller and a feedback force controller. The feedback force controller takes the COM as the operating point to achieve a compensation of the motion of COM. We have experimentally demonstrated that COM tracking performance is improved and actual ZMP trajectory is stabilized in the safety region using biped robot developed in our Lab.