Impedance control of quadruped robot and its impedance characteristic modulation for trotting on irregular terrain

Trotting on irregular terrain is a difficult task as undesirable impulse force by collision between robot foot and an obstacle makes the robot unstable. To cope with the problem, in this paper, variable impedance control algorithm changing leg impedance parameters according to the change of finite trot states is proposed. The state of quadruped trot is divided into five phases and the impedance parameters are changed to generate adequate response to the contact force in each locomotion phase. Simulation of trotting on irregular terrain with half-ellipsoidal trajectory has been performed with the control groups. The simulation has verified that the proposed control method shows outstanding performance and better stability for trotting on the highly irregular terrain.