Enhanced error modeling for a 3-RSS/S parallel mechanism in precision forming

Abstract

This paper proposes a part-oriented kinematic error modeling framework for a 3-RSS/S parallel manipulator used in precision forming. Departing from traditional trajectory-focused methods, the study establishes a direct linear mapping from 63 independent geometric error sources to workpiece surface deviations using small-displacement screw theory. Based on the developed model, the non-uniform error distribution and dominant sensitivity parameters, such as joint offsets, are effectively identified. To verify the rationality of the proposed approach, a set of preset geometric errors was introduced, and the predicted results were compared with numerical reference solutions under identical conditions. The comparison shows a prediction accuracy of 98.2%, demonstrating good consistency and reliability of the model. This approach enables robot calibration via direct part measurement, offering a cost-effective and efficient solution to enhance product consistency in industrial manufacturing.