In this article, the hydraulic drive unit that drives the movement of the joint of a legged robot was researched, aiming at improving the control accuracy of the position-based impedance control system with dual input and single output. The state feedback control containing more state information of the system was adopted to replace the traditional output feedback and proportional-integral-derivative (PID) control, through the real-time calculation of the time-varying parameters of the servo valve flow, the nonlinear state space expression of the system was derived, the state feedback matrix and the input transformation amplifier were obtained and the full-dimensional state observer was designed. The experimental results show that the designed full-dimensional state observer can track the state variables of the actual system better. Compared with the traditional output feedback and PID control, state feedback control performs better in aspects of accuracy and system dynamics for the position-based impedance control system, which can further improve the compliance performance of the robot.

中文翻译：

---

基于全维状态观测器的腿式机器人液压驱动单元状态反馈阻抗控制

本文对驱动腿式机器人关节运动的液压驱动单元进行了研究，旨在提高双输入单输出基于位置的阻抗控制系统的控制精度。采用包含更多系统状态信息的状态反馈控制代替传统的输出反馈和比例积分微分（PID）控制，通过实时计算伺服阀流量的时变参数，非线性推导了系统的状态空间表达式，得到了状态反馈矩阵和输入变换放大器，设计了全维状态观测器。实验结果表明，所设计的全维状态观测器能够更好地跟踪实际系统的状态变量。