Abstract
Linear resonant actuators (LRAs) have been used and studied because of high efficiency. However, the amplitude of LRAs severely decreases when external loads are applied. As a solution to this problem, we have proposed an external load estimation method using two signals of the back-EMF. However, the proposed method was effective only under unipolar drive. This paper proposes load and amplitude estimation method for LRAs using two back-EMF signals under bipolar PWM feedback control. The effectiveness of this method was verified through 2-D FEM analysis of our code.
