Abstract: There are various kinds of disturbances in the digital hydraulic cylinder, including uncertain parameters and uncertain nonlinearity. These factors will limit the high precision position control of the digital hydraulic cylinder. Aiming at high precision position control of digital hydraulic cylinder, a control strategy combining backstepping control with nonlinear disturbance observer is proposed to improve the tracking accuracy of position control. Firstly, the nonlinear control model of the digital hydraulic cylinder is established. Based on Lyapunov method, the designed system controller can guarantee the global stability of the system. Finally, the effectiveness of the control strategy is verified by MATLAB/Simulink simulation software. Simulation results show that the control strategy can effectively reduce the position tracking error, phase lag, steady-state limit cycle and low-speed crawling caused by uncertain parameters and uncertain nonlinearity. At the same time, it can improve the response speed of the system, make the system more robust and improve the position tracking quality.

Key words: Nonlinear disturbance observer, backstepping control, Lyapunov method, MATLAB/Simulink; phase lag, steady-state limit cycle, low-speed creeping

摘要： 数字液压缸存在各种类型的扰动，包括参数不确定和不确定非线性，这些因素会限制数字液压缸高精度位置控制。针对数字液压缸高精度位置控制，提出一种反步控制与非线性干扰观测器相结合的控制策略以提高位置控制跟踪精度。首先建立了数字液压缸的非线性控制模型，基于李雅普诺夫方法从理论上证明了所设计的系统控制器能够保证系统全局稳定性，利用MATLAB/Simulink仿真软件验证所设计的控制策略的有效性。仿真结果表明，该控制策略能有效地减小由参数不确定和不确定非线性给系统带来的位置跟踪误差、相位滞后、稳态极限环和低速爬行现象，同时提高了系统的响应速度，使系统具有更强的鲁棒性，改善了位置跟踪品质。

关键词: 非线性干扰观测器, 反步控制, 李雅普诺夫方法, MATLAB/Simulink, 相位滞后, 稳态极限环, 低速爬行