On the nonlinear control of hydraulic servo-systems

The control problem of a hydraulic servo-system is addressed. The performance achievable by classical linear controllers, e.g. PD, are usually limited due to the highly nonlinear behavior of the hydraulic dynamics. This paper adopts the backstepping design strategy to develop a Lyapunov-based nonlinear controller for a hydraulic servo-system. Load, hydraulic and valve dynamics are incorporated in the design process. An adaptation law is also proposed to deal with uncertainties in hydraulic parameters. The approach can be further extended to the control of hydraulically driven manipulators. Both simulation and experimental results are provided to show the effectiveness of the proposed method