Nonlinear adaptive nonsmooth dynamic surface control of electro-hydraulic systems

This paper discusses the development of an adaptive nonsmooth dynamic surface control (ANDSC) scheme to improve the motion control of SISO electro-hydraulic (EH) systems. A nonlinear EH model is developed for a typical system driven by single-rod actuators. ANDSC takes into account the parameter variations due to change in load inertia, bulk modulus, etc. and improves system robustness to uncertain nonlinearities representing the external disturbances and unmodeled friction forces. The discontinuous projection based adaptation ensures good overall performance. The controller guarantees arbitrarily small bounded tracking error in the presence of model uncertainties. The performance of the proposed approach is analyzed through realistic numerical simulations.