Disturbance Response and Force Control of a Magnetic Lead Screw Actuator

Abstract

This paper presents the disturbance response and sensor-less force control of a magnetic lead screw actuator (MLSA) that generates linear motion; it is composed of a magnetic lead screw and a rotary motor. This MLSA exhibits elasticity owing to magnetic spring properties, and it can respond flexibly against disturbances. The implemented magnetic lead screw has a spiral structure composed of arc shape permanent magnets and soft iron teeth instead of a spiral shape permanent magnet. This design advantageously reduces the number of parts and simplifies assembly. In the experiment, both the MLSA and a ball screw actuator undergo forced oscillation induced by a load actuator. Each actuator is controlled to maintain the zero contact force. The root mean squared error of the MLSA was found to be smaller than that of the ball screw actuator, demonstrating superior disturbance response of the MLSA. In addition, the effectiveness of the sensor-less force control method focused on a magnetic phase difference was verified through modeling of thrust and friction characteristics in the experimental results. Control experiments indicate that the MLSA can regulate force without the need for a force sensor.