Robust tracking of a two-fingered micromanipulation system working through the focus of an optical beam

This paper presents a study of the control problem of a laser beam illuminating and focusing a microobject subjected to dynamic disturbances using light intensity for feedback only. The main idea is to guide and track the beam with a hybrid micro/nanomanipulator which is driven by a control signal generated by processing the beam intensity sensed by a four-quadrant photodiode. Since the pointing location of the beam depends on real-time control issues related to temperature variation, vibrations, output intensity control, and collimation of the light output, the 2-D beam location to the photodiode sensor measurement output is estimated in real-time. To overcome this problem, the Particle Filter (PF) algorithm is used to estimate the position of laser beam. The dual manipulators are controlled by combining different performance dynamics (micro and nano manipulators) in order to track a laser beam with very-high precision in a dynamics operating mode.