Expanding Control Range of Nonlinear Precision Tracking Systems with a Linear Electric Motor by Means of Adaptive Control

Abstract

This paper considers the mathematical description of a servo drive system with a linear electric motor for the direct valve control system instead of the flapper–nozzle system. The description relies on the physical approach to determining electromagnetic parameters and electromechanical characteristics of electric motors. The obtained nonlinear traction characteristic and the resulting characteristic from the action of electromagnetic force and elasticity of the centering spring are used to determine the motor stroke limitations. The nonlinear action of counter-EMF against a rising electromagnetic time constant is substantiated. The solution proposed for the electrohydraulic tracking system is an adaptive control algorithm with an exomodel synthesized by the Lyapunov method that provides dissipativity of adaptation processes and expands the control range. The results of the practical tests of the adaptive control system are considered by the example of a servo system in the MATLAB/Simulink suite and on physical servo drive models.