Abstract
This thesis presents the development of a six-DOFs motion measurement system (MMS). The motion measurement device (MMD) is applied on multi-axis machine tools for the measurement of errors. The necessary measuring procedures are proposed for the measurement of positioning errors of linear and rotary axes of a machine tool and for the measurement of dynamic contour errors of simultaneously driven axes. Furthermore, a long distance measurement method is proposed to overcome the limitation of the measuring workspace of the MMD. This measurement system can identify the actual axis from the measured data, build the ideal reference coordinate of the machine tool, and construct the coordinate transformation between the MMD coordinate system and the ideal reference coordinate system. By entering the machine tool’s nominal design data, the MMS can identify all geometric errors of the tested machine tool. For three-axis CNC machine tool, this includes three squareness errors between three machine axes and six motion errors of each machine axis, or totally 21 geometric errors. For five-axis CNC machine tool, this includes three squareness errors between three linear axes, six motion errors of each machine axis, eight link errors of the two rotary axes, five assembly errors of the main spindle and six motion errors of each machine axis, or totally 46 geometric errors. The proposed measurement methods and the data processing program are tested and results are compared with these of a laser interferometer measuring system. The experimental items include the evaluation of the linear and rotary errors by positioning of a linear axis, and the dynamic responses of the step inputs. The results prove the correctness of the developed system. The most significant feature of the developed measurement system is that the errors of a CNC machine tool can be measured in one single reference coordinate system, including the geometric errors at static positioning and the dynamic contour errors of a continuous circular motion and of a non-continuous corner motion.