A unified approach to the accuracy analysis of planar parallel manipulators both with input uncertainties and joint clearance

This paper presents a unified approach to predict the accuracy performance of the general planar parallel manipulators (PPMs) both due to the input uncertainties and the joint clearance. Based on the theory of envelope, a geometric method is employed to uniformly construct the indeterminate influences of these two error sources on the pose (position and orientation) deviation of the manipulators. According to the generalized kinematic mapping of constrained plane motions, the end-effector's exact output error bound for a specified configuration can then be obtained as an accurate and complete description for the manipulator's accuracy performance, from which not only the maximal position and orientation errors but also their coupling relationship can be derived. The planar 3-RPR manipulator is intensively studied as a numerical example and several numerical simulations are provided to demonstrate the correctness and effectiveness the proposed approach.

► A unified approach is presented for the accuracy analysis of the general PPMs.
► Both effects of the input uncertainty and the joint clearance are taken into account.
► The generalized kinematic mapping is used to set up the models of the error sources.
► The numerical results have verified the effectiveness of the proposed approach.