Artifact Calibration of Parallel Mechanism (1st Report)

Calibration of a parallel mechanism using a specified artifact is effective method. However, there are strong correlations between each parameter in an artifact calibration of a parallel mechanism. Therefore, it is difficult to identify all kinematic parameters included in a kinematic model of the parallel mechanism from measuring data. In this research, we propose to use a priori knowledge of the kinematic parameters and to improve mathematical condition of Jacobian matrix. Using the priori knowledge, all kinematic parameters of the parallel mechanism are identified in the artifact calibration with the least squares method. Firstly, the least squares method with the priori knowledge is formulated. Secondly, design values and tolerances of the kinematic parameters are used as the priori knowledge in the least squares method. Finally, the artifact calibration for the parallel mechanism with the priori knowledge is demonstrated. Using this method, all kinematic parameters are converged to adequate values. The simulation for this method directly implies that the kinematic calibration with a priori knowledge for artifact calibration of parallel mechanism in this research is useful to calibrate all kinematic parameters without divergence in the least squares method.