|Sliding Mode Robust Control of Hydraulic Drive Unit of Hydraulic Quadruped Robot
Zhu Rui, Yang Qingjun*, Liu Yudong, Dong Rizhi, Jiang Chunli, and Song Jiaxing
International Journal of Control, Automation, and Systems, vol. 20, no. 4, pp.1336-1350, 2022
Abstract : This paper focuses on the position control of the quadruped robot hydraulic drive unit (HDU). The proposed control strategy has the advantages of excellent output tracking performance, strong robustness, no chattering and low computational complexity. HDU has the characteristics of nonlinearity and parameter uncertainty, coupled with unpredictable external interference, which makes it difficult to achieve precise position control. In this paper, we first establish the mathematical model of the HDU based on the actual parameters and obtain the state space of the system. Through the pole placement, the simplified system can easily achieve the expected control goal. Then, the state equation of the error system is constructed, and the nonlinearity, parameter uncertainty and external interference of the HDU are summarized as the matched and unmatched uncertainties of the system. The integral sliding mode control (ISMC) is used to derive the control law, and the response characteristics of the system when pole placement and state feedback H∞ control are used for the nominal control are compared. It can be concluded that the system with state feedback H∞ control for nominal control has stronger robustness and can resist the unmatched uncertainties. Finally, the control law of the simplified system is used as feedforward and combined with the ISMC of the error system, the output tracking control framework of the HDU is proposed. Simulations and experiments show that the proposed control method has excellent tracking performance and strong robustness.
"Hydraulic drive unit, integral sliding mode control, output tracking, position control, robust control. "