A Nonlinear Control Method for Asymmetric Hydraulic Cylinder Based on Incremental Digital Valve Control

In this paper, an output feedback nonlinear control is proposed for an asymmetric hydraulic cylinder based on incremental digital valve control system with unmodeled disturbances and parametric uncertainties. It's composed of a high gain state observer (HGO) and a dynamic surface sliding mode controller. The high gain state observer is designed to estimate the unmeasured system states. The dynamic surface sliding mode controller is designed to stabilize the closed-loop system. The proposed controller accounts for not only the unmodeled disturbances, but also the parametric uncertainties. In theory, the controller guarantees a prescribed tracking transient performance and final tracking accuracy even in the presence of unmodeled disturbances and parametric uncertainties. The effectiveness of the proposed method is verified via simulation.