BALLSCREW PRELOAD DEVICE BASED ON GIANT MAGNETOSTRICTIVE ACTUATOR: DESIGN, MODELLING ANALYSIS AND CONTROL SIMULATION STUDY.

To achieve automatic measurement and control of the ballscrew preload force, a novel preload device with two-end outputs based on giant magnetostrictive actuator (GMA) is designed. The mechanical structure and its working principle are presented and the electromagnetic field simulation is adopted to analyse the reasonability of the output preload force. Based on the above, the mathematical model of the preload device is established according to the piezomagnetic equation and the Newton second law. To improve the dynamic response speed and the steady-state output performance, the fractional-order PID controller (FPID or PIλDμ controller) is designed to form a closed-loop control system. The simulation study on the control performance of the closed-loop system is carried out in this paper. When the PIλDμ controller is adopted, the results demonstrate good control performance with an overshoot of step response of 1.77% and an adjusting time of 2.73 x 10-4 (s). Furthermore, with the proposed control algorithm, the tracking error is less than 4.5 x 10-8 (m) when tracking the sinusoidal displacement input of 3.0 x 10-6 sin wt (m) at low frequencies. [ABSTRACT FROM AUTHOR]