Kinematic and geometric error verification and compensation of a three axes vertical machining center

This paper discusses about kinematic and geometric error, which are the basic inaccuracy of the machine tool. For a three axes machine, there are 21 error components (3 linear position errors, 6 straightness errors, 9 angular errors and 3 squareness errors). Each individual error is measured directly by laser interferometer. The derivation of the kinematic and geometric error is based on the assumption of rigid body motions. It utilizes homogenous transformation matrices to create a kinematic and geometric mathematical error model which is useful for identifying all error within the working volume. The developed mathematical error model is used to calculate and predict the error vector to compensate error in each machine movement. The error vector at an intermediate position between the measured point is estimated by back-propagation neural network.