Hysteresis compensation in electromagnetic actuators through Preisach model inversion

In this paper, the classical Preisach independent domain model is used to capture the essential characteristics of hysteresis nonlinearity in electromagnetic actuators made of soft ferromagnetic material. Experimental results convincingly demonstrate its ability to accurately model electromagnetic hysteresis for variations in input current, airgap, and orientation, The Preisach model is then inverted and incorporated in an open-loop control strategy that regulates the electromagnetic actuator and compensates for hysteretic effects. While evaluating the performance of this compensation strategy experimentally, hysteresis-free regulation of the electromagnetic actuator is obtained, for variations in input current, airgap, and orientation. Hysteresis is also effectively compensated for desired force trajectories of frequencies up to 100 Hz. Thus, the experimental results demonstrate consistent performance of the open-loop control strategy based on Preisach model inversion, in satisfactorily regulating the output of the electromagnetic actuator to the desired trajectories. Compensation of faster variations may be possible, but could not be experimentally verified due to limitations in implementable sampling and control rates for the instrumentation.