Experimental tolerance design of robot manipulators accounting for positioning accuracy reliability

Abstract

A new tolerance design method based on experimental design and positioning accuracy reliability is presented to deal with uncertainties of robot manipulators resulting from manufacturing and assembly processes. Initially, the performance function of positioning accuracy is established according to the kinematic model and response surface technique. An analytical algorithm for positioning accuracy reliability calculation is developed based on eigen-decomposition and saddlepoint approximation methodologies. Inner orthogonal arrays of kinematic parameter tolerances along with the outer uniform arrays of joint variables are then constructed to analyze significant tolerances that affect the positioning accuracy reliability within the entire workspace. Finally, the applicability and performance of the proposed method are verified by case studies of a two-link planar manipulator and a six-degree-of-freedom robot manipulator. The results confirmed that the proposed method can efficiently and accurately analyze the positioning accuracy reliability, and the method recognizes the impact of kinematic parameters on the motion performance which is able to guide the tolerance range selection of robot manipulators.