SELF-TUNING GENERALIZED PREDICTIVE CONTROL OF AN ELECTROHYDRAULIC ACTUATOR

This paper deals with the design and implementation of a generalized p redictive controller for the position control of a single vane rotary jack, by mean of an RST regulator. The actuator is represented by an e quivalent fourth-order linear model including integration, first-order , and second-order effects. Significant changes in model parameters ve rsus operating conditions justify dynamic regulator setting by an indi rect adaptive scheme. In particular, the dominant mode varies from the badly damped, low-frequency hydraulic one to the over-damped, high-fr equency servovalve one. The whole regulator design is made by actuator knowledge model simulation. Difficulties are noted, due to real time GPC regulator synthesis at a 2 ms sampling rate and to quantization er rors that produce a ringing control signal. Finally, experiments confi rm the simulated actuator behaviour and validate the regulator paramet er design or selected solutions to the above-mentioned problems. Measu red responses are presented for small amplitude (ADC resolution effect s), medium amplitude, or high amplitude (saturations effects) set poin ts and for load inertia or supply pressure steps, attesting to the sig nificant improvement in actuator precision and dynamics obtained by su ch a control strategy.