Automatic micromanipulation using multiscale visual servoing

The paper deals with the manipulation of silicon microcomponents in order to assembly automatically. The size of the components vary from 600 mum times 400 mum times 100 mum to 300 mum times 300 mum times 100 mum with a notch of 100 mum thickness on every side. The microassembly process is split up into elementary tasks (aligning component, positioning component, centering component, opening gripper, ...) where every one is achieved by visual servoing. The control laws are of the type exponential or polynomial decrease of error according to the task. The performing of the latter has required the implementation of an effective tracking algorithm in combination with a depth-from-focus technique in order to maintain the target in focus and to recover the distance between the gripper and the component. The process includes the adaptation of the video microscope magnification to the required resolution (coarse to fine servoings). A multiple scale modelling and calibration of the photon video microscope is performed. The picking and placing of above components were achieved : the errors of positioning are respectively 1.4 mum in x and y and 0.5 degree in orientation.