Cheng Y. Lin

Kinematic calibration of manipulators with closed loop actuated joints

A method for performing forward kinematic calibration of manipulators having one or more closed-loop-actuated joints is presented. The technique is an extension of algorithms designed for open-loop jointed manipulators. The calibration is equivalent to minimizing an objective function subject to constraints. The objective function is taken as the integral of end-effector position and orientation error. The constraints arise from the closed-loop mechanisms present in the manipulator.<<ETX>>

Accuracy Test From Kinematic Parameter Errors in a Closed-Loop Robot

As it is impossible to construct a manipulator without any parameter errors during the manufacturing processes, the major objective of this paper is to see the effects of these errors on the accuracy of a closed-loop robot. A simulated robot with a 3D constraint is used in this numerical test. Three types of parameter errors are studied: (1) link length, (2) joint misalignment, and (3) joint encoder offset. In this test, a small variation is added to one of the link parameters, the accuracy is thus obtained by using forward kinematic transformations. A numerical method is proposed to calculate the dependent variables for each set of joint encoders. The results are also compared to an open-loop robot having the same parameter errors.