Examination of Vibration Control of Linear Oscillatory Actuator

Abstract

Linear oscillatory actuators (LOAs) are widely used in linear-motor shavers, electric toothbrushes and mobile phone vibrators as high-speed oscillatory driving devices. The maximum amplitude of the mover is obtained at a resonance frequency that is determined from the spring constant and the mass of the mover. However there is a problem with these actuators: the amplitude decreases sharply when the driving frequency differs from the resonance frequency in a mechanical vibration system with small damping. In this paper we propose a control of resonance frequency in which the thrust, which shows the characteristics of a spring, is generated based on the displacement of the mover and damping factor in which the thrust, which shows the characteristics of a damping, is generated based on the velocity of the mover. The proposed method ensures that the resonance frequency always corresponds to the driving frequency and that rapid changes in the amplitude are avoided.