Discrete-Time GPI Control of the Hydrostatic Unit in a Hydro-Mechanical Transmission

Hydro-mechanical transmissions are employed in many vehicle applications due to their advantage of a continuously variable transmission ratio. The main issue in their deployment, however, is a precise control of the hydrostatic unit within this system, whose characteristics are highly nonlinear and affected by unknown disturbances. Many control concepts for such transmissions have already been proposed, including both model-based and model-free approaches. In this paper, the design and simulation results are presented for a discrete-time version of Generalized Proportional Integral (GPI) control applied to the hydrostatic unit of a hydro-mechanical transmission. In contrast to previous work, the motor volumetric displacement is constant, which leads to a single-input single output (SISO) control approach. The discrete-time GPI controller can be easily implemented on an electronic control unit (ECU) and outperforms a classical PID control in a comparison. Simulation results using a validated system model from previous research indicate a promising tracking performance.