Robust control approach for a hydraulic differential cylinder system using a Proportional-Integral-Observer-based backstepping control

Abstract

This paper focuses on the design of an observer-based backstepping controller for systems with model uncertainties and measurement noise in order to assure suitable tracking performance as well as robustness against unknown inputs. System states and unknown inputs, such as model uncertainties and disturbances, are estimated using a high gain Proportional-Integral-Observer. The novelty of this contribution lies in combination of backstepping controller and PI-Observer to improve the tracking performance of the motion behavior and validation of the proposed method experimentally. Detailed examination shows the performance behavior with respect to practical aspects, represented by noisy measurements as well as model uncertainties. The designed control scheme is experimentally validated and compared with the industry standard designed proportional controller and the sliding mode controller as a known practical robust control approach using a hydraulic differential cylinder system. Unknown external forces and model uncertainties are assumed as unknown dynamical inputs acting on the nonlinear system. The closed-loop stability is proven using Lyapunov theory.