Uncertainty compensatory sliding-mode control method of hydraulic position servo system

Abstract

The invention discloses an uncertainty compensatory sliding-mode control method of a hydraulic position servo system. The uncertainty compensatory sliding-mode control method comprises the steps of firstly, establishing a mathematic model of the hydraulic position servo system, then respectively designing a mismatching disturbance observer and a matching disturbance observer, designing a sliding-mode controller based on the mismatching disturbance observer and the matching disturbance observer, and finally proving the global asymptotic stability of the system according to a Lyapunov stability principle. By means of the uncertainty compensatory sliding-mode control method, the gain of discontinuous terms of a sliding mode is remarkably reduced, and meanwhile accelerated speed information of the system is not used, so that matching uncertainty nonlinearity and mismatching uncertainty nonlinearity simultaneously exist in the system, asymptotic tracking steady-state performance is obtained, the capacity of resisting to matching and mismatching uncertainty and nonlinearity of the uncertainty compensatory sliding-mode control method applied in the hydraulic position servo system is improved, and good tracking performance is obtained.

Description

technical field [0001] The invention belongs to the technical field of electro-hydraulic servo control, in particular to a sliding mode control method for uncertainty compensation of a hydraulic position servo system. Background technique [0002] The hydraulic servo system has outstanding advantages such as large power-to-weight ratio, fast response and strong anti-load rigidity, and has been widely used in many important fields. Electrohydraulic servo system is a typical nonlinear system, which contains many nonlinear characteristics and modeling uncertainties. Nonlinear characteristics include servo valve flow pressure nonlinearity, friction nonlinearity, etc. Modeling uncertainties include parameter uncertainties and uncertain nonlinearities, among which parameter uncertainties mainly include load mass, viscous friction coefficient of actuator, leakage coefficient, servo valve flow gain, hydraulic oil elastic modulus, etc. Deterministic nonlinearity mainly includes unm...

AI Technical Summary

Problems solved by technology

Although perfect asymptotic tracking performance can be obtained in theory, the model of the actual system cannot be known precisely, and there will always be modeling uncertainty, which will deteriorate the tracking performance obtained by theoretical analysis

Although the adaptive control method can deal with the problem of parameter uncertainty, it can only obtain the steady-state performance of asymptotic tracking under the assumption that there is no external disturbance in the system.

Due to the mismatch uncertainty in the system, the basic idea of ​​the traditional sliding mode control method is to overcome the mismatch and matching uncertainty by increasing the robustness of the controller to reach the sliding mode surface. However, even if the sliding mode After the above, the systematic tracking error still cannot be zero under the interference of mismatch uncertainty, and only a uniformly bounded steady-state tracking error related to the upper bound of mismatch uncertainty can be obtained

Moreover, increasing the robustness of the controller by increasing the gain of the discontinuity item is likely to excite the high-frequency dynamics of the system in practical applications and make the system unstable

Therefore, the traditional sliding mode control method has great engineering limitations

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