A novel miniature hydraulic actuation system and offset to long hose effect

Abstract

For its compact and flexible design, a novel miniature hydraulic actuation scheme is proposed for use in applications especially where both size and power are extremely important. The system works on a volume-controlled method using miniature cylinders. In order to describe the impact of hose deformation on the system, a lumped-parameter hose model is proposed, and coefficients in the model are determined on the basis of experiments with an existing prototype. A position tracking controller with a disturbance observer is designed for a miniature hose-connecting hydraulic actuation system. Tracking control for the target displacement is arranged as an external circuit of pressure compensation to eliminate the tracking error and an inner circuit of pressure compensation which operates by observed disturbances and oil pressure in the hose. Lyapunov theory is employed to verify the stability of the system with the disturbance observer. The disturbance observer-based controller has much better tracking performance than conventional proportional-integral-derivative controllers, which can substantially offset negative effects of the hose.