Accuracy enhancement of industrial robots by on-line pose correction

This paper presents a novel, cost-effective dynamic pose correction (DPC) strategy to address the issues on the accuracy enhancement of industrial robots. This strategy, also known as visual-servoing, uses a photogrammetry based 6D measurement device to track the position and orientation of the robot's end-effector in real-time. To realize this strategy, we first propose a root mean square (RMS) method to filter the noise from the pose measurements. The estimated pose from the sensor serves as a feedback for visual-servoing system. Next, a DPC controller is designed and integrated with a FANUC robot controller through FANUC's dynamic path modification (DPM) software package. As a result, the robot is guided to the desired pose in real-time and hence the positioning accuracy is enhanced. Extensive experimental tests of the proposed algorithm have been carried out. The experimental results demonstrate that the pose accuracy of the robot (a FANUC M-20iA) for stationary tasks has been improved to 0.050 mm and 0.050° for position and orientation respectively.