Reduced Order Model Based Output Feedback Control for Hydraulic Quadruped Robot Single Leg

An output feedback control method is introduced to the displacement tracking control of the hydraulic drive system of a hydraulic quadruped robot in this paper, only the motion displacement is required for the control implementation, achieving high performance tracking control of hydraulic quadruped robot foot trajectory. By using singular perturbation theory to simplify system model, the unknown dynamics are lumped as one term, solving the problem of mechanical/hydraulic double dynamics coupling system with mismatched uncertain disturbances. Then the extended state observer(ESO) is designed to estimate the velocity and unknown dynamics of the hydraulic drive system. The control law is designed based on reduced order model and extended state observer, and the stability of the system is proved theoretically. Extensive comparative co-simulations and experiment based on a hydraulic quadruped robot single leg are conducted. From the comparison of co-simulation results, it can be seen that the control effect of the proposed method is significantly improved, and the experimental results verify the effectiveness of the proposed control method.