|A Nonlinear Model-based Variable Impedance Parameters Control for Position-based Impedance Control System of Hydraulic Drive Unit
Kai-xian Ba, Guo-liang Ma, Bin Yu*, Zheng-guo Jin, Zhi-peng Huang, Jun-xiao Zhang, and Xiang-dong Kong
International Journal of Control, Automation, and Systems, vol. 18, no. 7, pp.1806-1817, 2020
Abstract : In this paper, aimed at the problem of control accuracy when the traditional position-based impedance control is applied in the hydraulic drive unit (HDU) of legged robot, a kind of nonlinear model-based variable impedance parameters controller (MVIPC) is designed. First, the mathematical model of position-based impedance control for HDU is given. Second, the performance of traditional position-based impedance control is tested on the HDU performance test platform under different working conditions, and the experimental results show that the control accuracy of this control method needs to be improved greatly. Thirdly, the control idea of MVIPC is described, and the theoretical derivation is deduced. MVIPC considers the high-order dynamic characteristics of servo valve, pressure-flow nonlinearity of servo valve, oil compressibility and load characteristics. Finally, the control performance of MVIPC is verified on the HDU performance test platform. The experimental results show that MVIPC can significantly improve the performance of traditional position-based impedance control, and have an excellent adaptability under different working conditions. This research can provide an underlying control method of hydraulic systems during the robot locomotion.
Hydraulic drive unit (HDU), legged robot, model-based variable impedance parameters compensator (MVIPC), position-based impedance control