Zero Moment Point based pace reference generation for quadruped robots via preview control

Legged robots have significant advantages over other types of mobile robots when task at hand requires the robot to overcome obstacles. This paper presents a reference trajectory generation method for a quadruped robot for pace gait on a flat surface. The approach is based on the Zero Moment Point (ZMP) stability criterion and the Linear Inverted Pendulum Model (LIPM). ZMP reference trajectories for pace is proposed, from which reference trajectories for the Robot Center of Mass (CoM) references are obtained by applying preview control. The position of leg joints are computed using inverse kinematics according to CoM reference trajectory. Proposed reference trajectory generation synthesis is tested through full-dynamics 3D simulation. A 16-degrees-of-freedom (DOF) quadruped robot model is used in the simulations. Simulation results show the success of the reference generation technique for the pace gait.