KINEMATIC CALIBRATION OF THE PARALLEL MECHANISM USING DOUBLE-BALL-BAR SYSTEM

Since that it’s difficult to realize full closed-loop feedback control,kinematic calibration becomes a method to heavily gain economic value and effectively enhance the accuracy of parallel kinematic machine.In general,kinematic calibration consists of four steps,i.e.error modeling,measurement,identification and compensation.A double-ball-bar(DBB) based kinematic calibration of the 5-DOF reconfigurable hybrid robot named TriVariant is prespnted.The first order error mapping function is formulated to link the measured data to the geometric source errors affecting the compensatable pose accuracy.The issue to place a DBB mount is also investigated in order to achieve sufficient robustness of parameter identification.The effectiveness of the proposed approach is verified by both computer simulation and experiments.Some key issues for the further enhancement of the pose accuracy are also addressed by examining the experiment results.