Robust Approach for Position Control of Hydraulic Differential Cylinder

The paper introduces a robust nonlinear control approach for the position control of hydraulic differential cylinder. The behavior of a hydraulic differential cylinder is highly nonlinear. A perfect model is usually not available. So nevertheless a robust control is required, to guarantee the performance of the cylinder, usually based on an imperfect model. The presented approach combining the classical feedback linearization approach and an extended Luenberger observer technique is robust to model uncertainties or unknown effects acting to the system, for example as unknown load, and can be applied to single-input single-output (SISO) nonlinear systems. It improves the robustness and extends the application area of feedback linearization control. The approach is implemented and tested on a hydraulic differential cylinder test rig. Theoretical proofs and experimental results are presented.