Indirect Adaptive Control of an Electrohydraulic Servo System Based on Nonlinear Backstepping

This paper studies the real-time position control of an electrohydraulic system using indirect adaptive backstepping. Electrohydraulic systems are known to be highly nonlinear and nondifferentiable. Backstepping is used for being a powerful, nonlinear control strategy and for its ability to ensure an asymptotic stability of the controlled system without canceling useful nonlinearities. On the other hand, hydraulic parameters are prone to variations; it is, therefore, useful to employ an adaptive control strategy in order to update the controller with the parameters variation. In such a case, indirect adaptive control is highly recommended, among other adaptive controller types, as it has the benefit of identifying the real system parameters value. Since not much literature is available for the indirect method as applied to the hydraulic systems, because of its implementation complexity, this paper shows how efficiently this method can handle the parameter estimates.