Development of a wire draw encoder based measurement system for robot calibration

Abstract

Industrial Robot sales are at an all-time high with wages offshore rising, robot prices down and performance up. And manufactures are adopting more automation than ever before. Meanwhile the automated automation is becoming more and more popular since it can improve the efficiency and reduce the labor cost. As well known, Industrial Robots have higher repeatability than accuracy. However, automated automation requires high absolute accuracy rather than repeatability. Fortunately, Kinematic Calibration can effectively improve the absolute accuracy of a Robot Manipulator. But most of the measurement systems for Robot Calibration are extremely expensive and this is a serious problem since seldom Robot System Integrators can afford the measurement system to calibrate their robots. So it becomes a rigid demand for developing a cost-effective measurement system for robot calibration. In this thesis, we proposed and developed a wire draw encoder based measurement system which compromises good accuracy, measurement range, operability and cost. Meanwhile the calibration algorithm based on Wire Draw Encoder Measurement System using POE Theory with the Adjoint Error Model was introduced. In order to overcome the draw backs of traditional wire draw encoder measurement system, we redesigned the structure and added additional sensors for compensation. With 4 generations' development of iteration, this Wire Draw Encoder based performs well under experiments and tests. Finally, we conducted calibration experiments on a 6-DOF Industrial Robot RA10L from Kawasaki and a SCARA Robot from QKM to validate the performance of this cost-effective measurement system.

Date of Award	2015
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology