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Design of a Six-DOF Motion Tracking System based on a Stewart Platform and Ball-and-Socket Joints



Yong Sik Kim, Shi Hongliang, Nicholas G. Dagalakis, Jeremy A. Marvel, Geraldine S. Cheok


Performance evaluation of industrial robots has been an interesting topic since the 1990s. For this, it is necessary to monitor the motions or activities of industrial robots continuously and correct them subsequently. In this case, an appropriate motion tracking system becomes important. In this paper, an affordable six degree-of-freedom (DOF) motion tracking system is described. The proposed system is designed based on a Stewart platform and able to continuously track six DOF motions of the target through six displacement sensors installed on the Stewart platform. The six sensors are calibrated with a laser tracking system. A modeling of the hexapod mechanism is developed based on forward kinematics and the Newton-Ralph method for real-time monitoring. Experimental results with a laser radar system demonstrate that the hexapod motion tracking system has a root mean square (RMS) position error of less than 2.89 mm, and RMS angle errors of 0.25 degrees. The proposed system is also tested with a commercial robot, showing that it monitors its six DOF motions and visualizes them in real-time.
Journal of Mechanism and Machine Theory


Motion tracking, linear potentiometer, Stewart platform, parallel mechanism, forward kinematics
Created March 1, 2019, Updated November 28, 2018