Abstract
Measurement noise, parametric uncertainties, and external disturbances broadly exist in electro-hydraulic servo systems, which terribly deteriorate the system control performance. To figure out this problem, a novel finite-time output feedback controller with parameter adaptation is proposed for electro-hydraulic servo systems in this paper. First, to avoid using noise-polluted signals and attain active disturbance compensation, a finite-time state observer is adopted to estimate unknown system states and disturbances, which attenuates the impact of measurement noise and external disturbances on tracking performance. Second, by adopting a parameter adaptive law, the parametric uncertainties in the electro-hydraulic servo system can be much lessened, which is beneficial to averting the high-gain feedback in practice. Then, integrating the backstepping framework and the super-twisting sliding mode technique, a synthesized output feedback controller is constructed to achieve high-accuracy tracking performance for electro-hydraulic servo systems. Lyapunov stability analysis demonstrates that the proposed control scheme can acquire finite-time stability. The excellent tracking performance of the designed control law is verified by comparative simulation results.
Highlights
The result of Theorem 1 shows that the proposed finite-time output feedback controller with parameter adaption has finite-time convergence performance
This method ensuring transient performance and final tracking accuracy is very important for precise motion control of hydraulic systems
In order to verify the dynamic tracking performance of the controller proposed in this paper, linear output feedback control with parameter adaptation (LOFC) and PID control method are compared separately
Summary
The electro-hydraulic servo system is a sort of highly non-linear system with various model uncertainties which is mainly manifested in the non-linear pressure and flow of the valve. The model uncertainties of the electro-hydraulic servo system can be divided into parameter uncertainties and uncertain nonlinearities, such as parameter change, external disturbances, nonlinear friction and so on. These problems have always restricted the development of advanced control and the decision-making algorithms for electro-hydraulic servo systems. The modeling uncertainties will seriously deteriorate the performance of the designed controller and lead to cycle oscillations and even instability in the system [6]
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