Optimal tracking control with observer-based disturbance compensation for a hydrostatic transmission

A decentralised approach is proposed in this paper for an optimal tracking control (OTC) of a hydrostatic transmission, which is commonly used in working machines. An unknown leakage volume flow and a resulting load torque have been taken into account as lumped disturbances. Together with unmeasurable system states, the normalised swashplate and the normalised bent axis angles, the proposed controller is extended by a nonlinear observer and a corresponding disturbance compensation. Thereby, the high tracking accuracy can be achieved for the normalised bent axis angle and the angular velocity of the motor as controlled variables. The efficiency of the proposed controllers is demonstrated by both simulations and experiments.