Sensor-guided manipulation in a manufacturing workcell

The main problem that we address in this paper is how a robot manipulator is able to track and grasp a part placed arbitrarily on a moving disc conveyor aided by a single CCD camera and fusing information from encoders placed on the conveyor and also from encoders on the robot manipulator. The important assumption that distinguishes our work from what has been previously reported in the literature is that the position and orientation of the camera and the base frame of the robot is a priori assumed to be unknown and is 'visually calibrated' during the operation of the manipulator. Moreover the part placed on the conveyor is assumed to be nonplanar, i.e. the feature points observed on the part is assumed to be located arbitrarily in R/sup 3/. The novelties of the proposed approach in this paper includes a (i) multisensor fusion scheme based on complementary data for the purpose of part localization, and (ii) self-calibration between the turntable and the robot manipulator using visual data and feature points on the end-effector. The principle advantages of the proposed scheme are the following. (i) It renders possible to reconfigure a manufacturing workcell without recalibrating the relation between the turntable and the robot. This significantly shortens the setup time of the workcell. (ii) It greatly weakens the requirement on the image processing speed.