Servo Control of Linear Variable Reluctance Actuators Using Augmented Feedback Linearization

Abstract

Solenoids are commonly used in fuel injection systems, in process automation, medical systems, etc. They have numerous advantages: they are fast, reliable, compact and produce a high force output, making them a competitive replacement option for purely mechanical actuators and pneumatic control valves. However, their coil inductance and electromagnetic force vary non linearly as a function of position and hence controlling it can be a significant challenge. It is found that conventional PI, PD, PID controllers fall short of providing acceptable performance. This work aims at developing a position control scheme for the solenoid using an augmented feedback linearization based approach. The augmented controller includes classical current regulation, a reduced-order feedback linearization and error integration. The control scheme is formulated and a multi-rate state feedback motion controller is designed to achieve acceptable performance. The control algorithm is validated using simulations and verified using experimental results.