比例阀控电液系统抗扰换向滞后补偿反步控制

Switch delay compensation and disturbance rejection control for proportional valve controlled electro-hydraulic system with backstepping method

针对比例阀存在换向滞后,电液系统受到的外部干扰,液压油弹性模量随渗入的空气变化、未建模动态,这些因素增加了设计电液位置控制器的难度,本文使用线性扩张状态观测器(LESO)对比例阀控电液系统的内部扰动、外部扰动、未建模动态进行估计,将虚拟控制量的非线性函数纳入抗扰反步控制器设计,实现比例阀控电液系统换向滞后补偿.分析了闭环系统的稳定性,证明当扰动导数有界时,观测误差和跟踪误差都有界,调整控制器增益与非线性项参数可使跟踪误差收敛到原点附近,仿真和实验表明,本文设计的控制器能显著缩短比例阀换向滞后、提高电液位置控制系统的跟踪速度、精度与抗扰能力.

It is difficult to design the controller for the electro-hydraulic system regulated by the proportional valve,because there are the switch delay,the external disturbance,the nonlinear friction,and the unmodeled dynamics as well as oil effective bulk modulus variation due to the entrained air.The linear extended state observer(LESO)is used to estimate the generalized disturbance including internal disturbance,the external disturbance and the unmodeled dynamics.Furthermore,the nonlinear function is designed in the disturbance rejection backstepping controller to compensate the dead-zone so that the load can follow the desired trajectory precisely.The stability of the system is analyzed,and it has been proven that both the estimation error and the tracking error are bounded when the derivative of the disturbance is bounded;moreover,the tracking error can converge to the neighborhood of the origin by adjusting controller gain and parameters of the nonlinear term.Simulations and experiments show that the switch delay can be reduced and the load can track the desired trajectory quickly and accurately under the external disturbance.