Self-Tuning Adaptive Speed Control of a Pump/Inverter-Controlled Hydraulic Motor System

In a hydrostatic transmission system the speed of the fixed displacement hydraulic motor can be controlled by varying either the pump displacement or the pump speed. The change of pump speed can be achieved via an inverter which governs the speed of an induction motor. In this paper, both the pump-controlled hydraulic motor system and the inverter-controlled hydraulic motor system are studied. A microcomputer-based self-tuning adaptive controller was designed and applied to both systems. A series of simulations and experiments was performed. The results show that both the pump-controlled system and the inverter-controlled system can be regulated to maintain a desired response under different speed commands, load inertias, oil temperatures and an external disturbance.