Kinematic Calibration of the 3-DOF Module of a 5-DOF Reconfigurable Hybrid Robot using a Double-Ball-Bar System

This paper deals with the kinematic calibration of a 3-DOF parallel mechanism using a double-ball-bar (DBB) system. The mechanism forms the main body of a 5-DOF reconfigurable hybrid robot named TriVariant that is a modified version of the Tricept, achieved by integrating one of its three active limbs into the passive one. The first order error mapping function is formulated to link the measured data and the geometric source errors affecting the compensatable pose accuracy. Issues to enhance the accuracy and efficiency of the calibration are investigated. The results are employed to a prototype machine calibration