Design and Comparison of Active Disturbance Rejection Approaches for the Velocity Tracking Control of Hydrostatic Transmissions

In this paper, two alternative versions of an active disturbance rejection (ADR) scheme, flat-filtering ADR and observer-based ADR, are investigated regarding the achievable tracking performance of a hydrostatic transmission. In the decentralized control structure, the control of the motor bent-axis angle is performed in a feedforward manner, whereas for the tracking control of the motor angular velocity is based on two different implementations of generalized proportional integral (GPI) control taking advantage of the flatness property. The proposed control schemes are evaluated and validated by means of both simulations and experiments on a dedicated test rig at the Chair of Mechatronics, University of Rostock.