基于改进自适应高阶滑模的液压缸位移跟踪控制

Hydraulic Cylinder Displacement Tracking Control Based on Improved Adaptive High-Order Sliding Mode

电液伺服系统具有高度非线性、模型参数不确定等特点,给液压缸位移跟踪控制造成了困难。高阶滑模是一种变结构非线性控制方法,它可以实现系统的鲁棒控制,同时抑制系统的抖动,非常适用于电液伺服系统的控制。但高阶滑模也存在控制器的参数难以设置、系统响应速度慢的问题。对此,提出在自适应高阶滑模的基础上加入比例反馈的复合控制策略。针对高阶滑模的控制参数难以设置的问题,提出基于时滞控制理论的参数自适应调整算法,既保证了系统稳定又降低了控制信号的抖动幅值。在自适高阶滑模的基础上加入比例控制以提高系统的响应速度。建立了电液伺服系统的仿真模型,仿真结果表明:自适应高阶滑模使控制信号的振幅进一步减小,有效抑制了液压缸的抖动;加入比例控制之后,系统的响应速度大幅提升,位移跟踪误差也显著减小。

Electro-hydraulic servo system has the characteristics of high nonlinearity and model parameter uncertainty,which makes it difficult for hydraulic cylinder displacement tracking control.High-order sliding mode is a variable structure nonlinear control method.Using this method can achieve robust control and attenuate chattering for the system,which is very suitable for the control of electro-hydraulic servo system.However,the high-order sliding mode also has the problems that the parameters of controller are diffi-cult to set and the system response speed is slow.For this reason,a composite control strategy based on adaptive high-order sliding mode and proportional feedback was proposed.An parameter adaptive adjustment algorithm was proposed based on time delay control to solve the problem that the control parameters were dfficult to set.Using this method,the asymptotic stability of the system was ensured and the chattering amplitude of the control signal was reduced.The proportional control was added on the bas is of adaptive high-order sliding mode control to improve the response speed.Finally,the simulation model of electro-hydraulic servo system was established.The simulation results show that the adaptive high-order sliding mode can further reduce the chattering amplitude of control signal,the hydraulic cylinder chattering caused by control signal is effectively suppressed;when the proportional control is added,the response speed of the system is greatly improved,and the displacement tracking error is also significantly reduced.