title: Digital current regulator for proportional electro-hydraulic valves with unknown disturbance rejection.
abstract: Solenoid current regulation is well-known and standard in any proportional electro-hydraulic valve. The goal is to provide a wide-band transfer function from the reference to the measured current, thus making the solenoid a fast and ideal force actuator within the limits of the power supplier. The power supplier is usually a Pulse Width Modulation (PWM) amplifier fixing the voltage bound and the Nyquist frequency of the regulator. Typical analog regulators include three main terms: a feedforward channel, a proportional feedback channel and the electromotive force compensation. The latter compensation may be accomplished by integrative feedback. Here the problem is faced through a model-based design (Embedded Model Control), on the basis of a wide-band embedded model of the solenoid which includes the effect of eddy currents. To this end model parameters must be identified. The embedded model includes a stochastic disturbance dynamics capable of estimating and correcting the electromotive contribution together with parametric uncertainty, variability and state dependence. The embedded model which is fed by the measured current and the supplied voltage becomes a state predictor of the controllable and disturbance dynamics. The control law combines reference generator, state feedback and disturbance rejection to dispatch the PWM amplifier with the appropriate duty cycle. Modeling, identification and control design are outlined together with experimental result. Comparison with an existing analog regulator is also provided.
authors.affiliation: Politecnico di Torino, Dipartimento di Automatica e Informatica, Corso Duca degli Abruzzi 24, 10129 Torino, Italy. Electronic address: enrico.canuto@polito.it.
authors.forename: Enrico
authors.initials: E
authors.lastname: Canuto
authors.affiliation: Atos SpA, Via alla Piana 57, 21018, Sesto Calende, Italy. Electronic address: wilber.acunabravo@polito.it.
authors.forename: Wilber
authors.initials: W
authors.lastname: Acuña-Bravo
authors.affiliation: Atos SpA, Via alla Piana 57, 21018, Sesto Calende, Italy. Electronic address: magostani@atos.com.
authors.forename: Marco
authors.initials: M
authors.lastname: Agostani
authors.affiliation: Atos SpA, Via alla Piana 57, 21018, Sesto Calende, Italy. Electronic address: mbonadei@atos.com.
authors.forename: Marco
authors.initials: M
authors.lastname: Bonadei
keywords: Current regulator; Disturbance rejection; Identification; Model-based control; Solenoid