Linear control of laser scanner driven by voice coil motor

A laser scanner driven by voice coil motor (VCM) was introduced and parameters of the established model were identified. Due to lots of high frequency optical noise in feedback loop, conventional methods, the improved PID control algorithm and the inverse design method based on optimal 2-order property of ideal closed-loop, which usually used for precise tracking of optoelectronic, cannot be employed for this laser scanner. This willl introduce unstablity and oscillates. After analyzing reasons of causing oscillation, a so-called feedforward control method based on the two methods above was used to resolve the contradiction between the oscillation and steady state error. At the same time, a low-pass filter was placed in the feedback loop according to the situation where feedback loop is filled with noise. The proposed method not only stabilizes the laser scanner but also eliminates hysteresis during linear scanning.