Planning and control in reconfigurable manufacturing workcell

Abstract

The main problem that we address in this paper is how a robot manipulator is able to manipulate a part in a reconfigurable workcell which consists of a moving disc conveyor; a single CCD camera and a 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 apriori assumed to be unknown; which is a common case in reconfigurable workcell and is `visually calibrated' during the operation of the manipulator. Moreover the part placed on the conveyor is assumed to be non-planar; i.e. the feature points observed on the part is assumed to be located arbitrarily in R3. The novelties of the proposed approach in this paper includes a (i) multi-sensor 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 re-calibrating 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.