Modelling and Simulation of a Hydrostatic Drive in a State Variable Controlled Loop

A dynamical model of a hydrostatic gear is presented and its performance tested with closed-loop measurements using a state-variable controller with full state observer. A "combined" approach to modelling hydrostatic drives is proposed - using physical knowledge, extensive simulations and as few measurements as possible - instead of the classical approach, consisting in exact modelling of each part according to its constructive data. It is shown that this approach leads more easily to a suitable model for controller design, as well as to screening of unnecessary model parts, even some that are usually considered very important. The possibility of further simplifications is briefly discussed at the end of the paper.