基于扰动观测器的电液系统压力控制

Disturbance observer based pressure control for electrohydraulic system

针对采用流量阀作为控制元件的电液系统,设计一种基于扰动观测器的非线性鲁棒压力控制器。在该系统中,压力控制性能受到负载流量的不利影响。研究中负载流量被分成时变的未知负载流量与可以建模的泄漏流量2个部分:前者是干扰压力控制的主要因素,为此在建立系统动力学模型的基础上设计非线性扰动观测器以估计未知负载流量;应对后者的方法则是首先建立其解析模型,然后在控制器中对其进行模型补偿。基于上述两点并考虑系统动力学的非线性特性,采用滑模控制技术综合系统压力的非线性鲁棒控制器。实验结果表明:所设计控制器在存在负载流量干扰的情况下实现精确且迅速的压力跟踪控制,表现出良好的性能鲁棒性。

Considering the electrohydraulic systems controlled by flow valves, a disturbance observer based nonlinear robust pressure controller was developed. The proposed method mainly focuses on the disturbance arising from load flow, which can be divided into two parts. One part is unknown and time-varying, named unknown load flow, which significantly affects pressure control in electrohydraulic systems. The other part can be modeled, named leakage flow. To account for the disturbance caused by unknown load flow, a nonlinear disturbance observer was designed to estimate it. The leakage flow was handled by model compensation in the controller. Based on the estimation of unknown load flow and the model of leakage flow, also taking into account nonlinear characteristics associated with the pressure dynamic at the same time, a nonlinear robust controller was synthesized via sliding mode control technology. Theoretically, the controller can achieve guaranteed robust transient performance and steady-state control accuracy. The proposed controller was tested on an experiment set. The experiment results show that using the raised controller, the system achieves fast and precise pressure tracking control, and the control performance is robust to unknown load flow.