On-the-machine Measurement System by Calibrating with Sphere (2nd Report) -Multiple Degree-of-Freedom Arm with Passive Joints for Holding a Probe -Katsushi FURUTANI, Kenji IWAMOTO and Naotake MOHRI In order to fabricate three-dimensional profiles with high accuracy, on-the-machine measurement is required. A method for on-the-machine measurement by calibration with spheres used for references has been developed. In this paper, an arm with passive joints for on-the-machine measurement is

more »

... As a prototype of the arm has 4-DOF (degrees of freedom) including 2 passive joints, the probing system totally has 7-DOF including DOF of the machine tool. The angle of the passive joints is changed by driving the NC table and the main axis of the machine tool where the arm is mounted. In order to calculate the optimal posture of the arm for the shape to be measured, a numerically analyzing method of the inverse kinematics is also proposed. The prototype of the arm has enough positioning accuracy to calibrate its posture. Shapes can be automatically measured with the accuracy of micrometers order by the on-the-machine measurement method.