Abstract: Planar flexible parallel manipulators, which concentrate the merits of both flexible manipulators and lower-mobility parallel manipulators, have become a hot spot of current researches. A simple and effective self-calibration approach for a planar flexible 3-RRR parallel manipulator is proposed and verified. Based on the error modeling, parameter identification equations are derived by vector chains. Actual poses of the manipulator during applications are measured on line by linear wire encoders, which have been calibrated by instruments through standard positioning holes of the static platform. According to the identification results deduced from the theoretical trajectory of numerical control system, the control model is compensated. As a result, the accuracy of the manipulator is greatly improved, and the study of the self-calibration by linear wire encoders is completed. In view of the great availability of measuring implements and modeling method, as well as the capacity of measuring the actual poses on line, this method is a practical solution to self-calibration of lower-mobility planar flexible parallel manipulators and an available measure for the closed-loop control.

Key words: Error modeling, Flexible parallel manipulator, Self-calibration