Multi-target position servo control of hydractive suspension based on extended state observer

The half suspension model established in this paper fully considers the non-linear characteristics of single-rod hydraulic actuators, and designs a sliding mode adaptive controller based on the existence of uncertain parameters and possible external uncertain disturbances in the system. Considering that some of the state variables required by the controller are not easy to obtain, an extended state observer is designed to observe the wheel vertical movement speed and the pressure of the rod cavity and non-rod pressure of the hydraulic actuator. The controller designed in this paper estimates the uncertain parameters through the adaptive law, and can still effectively adjust the body attitude when the system has a strong external disturbance signal. Through the simulation results, it can be seen that the controller always satisfies the hard constraints such as driving safety and suspension stroke due to the restricted mechanical structure while improving the ride comfort of the vehicle. Because the model takes into account the widely used asymmetric single-rod hydraulic actuators and external non-linear disturbances, and designs state observers for some unmeasured state variables, the controller designed in this paper is closer to reality.

本文所建立的半悬挂模型，充分考虑了单杆液压执行器的非线性特性，并基于系统中存在的参数不确定性和可能的未知外部扰动，设计了一种滑动模式自适应控制器。鉴于控制器所需的部分状态变量难以获取，本研究设计了扩展状态观测器，以监测车轮的垂直运动速度以及液压执行器的杆腔压力和非杆压力。所设计的控制器通过自适应律估计不确定参数，即使在系统遭受强烈的外部扰动信号时，仍能有效地调整车身姿态。仿真结果表明，该控制器在满足严格的约束条件，如驾驶安全性和悬挂行程等由限制性机械结构所设定的硬性限制的同时，还能提升车辆的乘坐舒适性。由于该模型兼顾了广泛应用的非对称单杆液压执行器和外部非线性扰动，并为部分未测量状态变量设计了状态观测器，因此，本文所设计的控制器更贴近实际应用场景。