Identification and Multi-Model PI Control of a Hydro-Motor under Variable Frictional Load

In this paper, identification and multi-model control of velocity in a rotary servo hydraulic system are carried out under variable frictional loads. Identification is performed in frequency domain, under five constant load conditions, and five linear models are obtained correspondingly. Afterwards, five PI controllers are designed using W-plane method, based on the identified models. A switching algorithm is then applied to properly determine the best model and select its corresponding controller, in any load condition. Experiments are carried out under full range variation of load and results indicate highly improved performances compared to the results of a fixed PI controller.