Dynamics compensation and rapid resonance identification in ultrasonic-vibration-assisted microforming system using magnetostrictive actuator

In this paper, a mechatronic system is developed to compensate for the hardware dynamics effect, and to achieve rapid resonance identification for an ultrasonic-vibration-assisted microforming system. Microforming has recently attracted great interests due to the need for miniaturized manufacturing systems in emerging applications. It has been demonstrated that significant benefits, such as the reduction of input energy and the prolongation of tool life, can be gained by introducing ultrasonic vibration into the microforming process, particularly when the vibration is maintained at the resonant frequency of the vibrating workpiece. However, the fundamental mechanism of ultrasonic vibration effect on the microforming process has not yet been understood; the electrical actuators currently used to generate the ultrasonic vibration are bulky and not suitable for miniaturization of the microforming system, and control of the ultrasonic vibration is primitive and far from being optimal. To tackle these challenges, a microforming platform based on a magnetostrictive actuator has been developed. The main contributions of this paper are two-fold: first, the use of a novel iterative learning control technique along with a vibration oscillation regulation circuit to compensate for the effect of the magnetostrictive actuator dynamics on the ultrasonic vibration generation, and thereby, maintain the same vibration amplitude across a large excitation frequency range; and secondly, the use of the Fibonacci search algorithm to achieve rapid online identification of the resonant frequency. Experimental results obtained on the developed magnetostrictive-actuator-based microforming system are presented and discussed to demonstrate the efficacy of the proposed approach.