Apple Inc.
Closed-loop control of linear resonant actuator using back EMF and inertial compensation

Abstract:

A system for providing closed-loop control of a linear resonant actuator using Back Electromotive Force (EMF) and inertial compensation is disclosed. In an embodiment, one or more inertial sensors are used to estimate low frequency motion of a haptic engine moving mass and compensate for the motion using a feedforward model, thus providing a more robust closed-loop control system for controlling the moving mass when subjected to low frequency disturbances by a user, for example, shaking or swinging the device.