Six Degree-of-Freedom Hand/Eye Visual Tracking with Uncertain Parameters

Algorithms for full 3D robotic visual tracking of moving targets whose motion is 3D and consists of translational and rotational components are presented. The objective of the system is to track selected features on moving objects and to place their projections on the image plane at desired positions by appropriate camera motion. The most important characteristics of the proposed algorithms are the use of a single camera mounted on the end-effector of a robotic manipulator (eye-in-hand configuration), and the fact that these algorithms do not require accurate knowledge of the relative distance of the target object from the camera frame. The detection of motion is based on a cross-correlation technique known as Sum-of-Squares Differences (SSD) algorithm. The camera model used introduces a number of parameters that are estimated on-line, further reducing the algorithms’ reliance on precise calibration of the system. An adaptive control algorithm compensates for modeling errors, tracking errors, and unavoidable computational delays which result from time-consuming image processing. Experimental results are presented to verify the efficacy of the proposed algorithms and to highlight the limitations of the approach. These experiments were performed using a multi-robotic system consisting of Puma 560 manipulators.