基于递推最小二乘法的阀控缸液压系统控制策略

Control strategy of valve-controlled cylinder hydraulic system based on recursive least square method

阀控缸液压系统存在建模不准确、动态控制精度较低和控制算法调试困难的问题,为此,提出了一种基于递推最小二乘法(RLS)的反步法动态面控制策略,并采用半实物仿真平台对其控制算法进行了调试验证。首先,建立了阀控缸液压系统非线性状态空间模型,推导了该系统的最小二乘矩阵形式和递推算法公式;然后,基于李雅普诺夫稳定性理论和动态面控制技术,建立了阀控非对称缸系统的控制模型,设计了一种基于RLS的反步法动态面控制器;最后,基于半实物仿真平台,对改造后的Linux操作系统进行了实时性验证,完成了阀控非对称缸系统参数辨识和基于RLS的反步法动态面控制试验任务。试验结果表明:RLS算法不仅能用于准确地估计系统模型参数,更能有效地适应系统模型参数的变化;相比于常规PID控制方法,基于RLS反步法动态面控制策略在阀控非对称缸系统稳定状态和换向的过程中,其动态控制精度分别提高了72.9%和20.3%,可为今后阀控缸液压系统建模及非线性控制策略研究提供较高的理论参考。

There are some problems in the hydraulic system of valve-controlled cylinder,such as inaccurate modeling,low dynamic control accuracy and difficult debugging of control algorithm.Therefore,a backstepping dynamic surface control strategy based on recursive least squares(RLS)was proposed,and its control algorithm was debugged and verified by hardware-in-the-loop simulation platform.The semi-physical simulation platform was used to complete the debugging and verification of the control algorithm.Firstly,the nonlinear state space model of the valve-controlled cylinder hydraulic system was established,and the least squares matrix form and recursive algorithm formula of the system were derived.Then,based on Lyapunov stability theory and dynamic surface control technology,the control model of valve-controlled asymmetric cylinder system was established,and a dynamic surface controller based on RLS backstepping method was designed.Finally,based on the semi-physical simulation platform,the real-time verification of the modified Linux operating system was carried out,and the parameter identification of the valve-controlled asymmetric cylinder system and the dynamic surface control test based on RLS backstepping method were completed.The experimental results show that the RLS algorithm can not only accurately estimate the system model parameters,but also effectively adapt to the changes of the system model parameters.Comparing with the conventional PID control method,the dynamic control accuracy of the dynamic surface control strategy based on RLS backstepping method is improved by 72.9%and 20.3%respectively in the stable state and commutation process of the valve-controlled asymmetric cylinder system,which can provide a high theoretical reference for the modeling of valve-controlled cylinder hydraulic system and the research of nonlinear control strategy in the future.