Enhancing Kinematic Calibration Accuracy for Parallel Manipulators Based on Truncated Total Least Square Regularization

This paper proposes a novel kinematic calibration method to address the ill-conditioned identification matrix problem and enhance the accuracy of Parallel Manipulators (PMs). The kinematic calibration method applies the Truncated Total Least Squares (T-TLS) regularization method to the inverse kinematic calibration of PMs and doesn't have the unit inconsistency issue and configuration selection issue. The performance of the T-TLS method in the inverse kinematic calibration of PMs that have the ill-conditioned identification matrix problem is compared to that of classical regularization methods, including the Truncated Singular Value Decomposition (TSVD) method and Tikhonov method, in simulations. Then, the kinematic calibration method is applied to a 3- PSS/S spherical PM prototype in the real world. For the 3- PSS/S spherical PM prototype, the kinematic calibration method can reduce the absolute angular errors of the end-effector from over 1.0 deg before calibration to less than 0.1 deg after calibration.