Geometrical Error Compensation

Abstract

In automated positioning machines such as Co-ordinate Measuring Machines (CMM) and machine tools, the relative position errors between the end-effector of the machine and the workpiece directly affect the quality of the final product or the process of concern. These positioning inaccuracies arise from various sources, including static/quasi-static sources such as geometrical errors from the structural elements, tooling and fixturing errors, thermally induced and load induced errors, and also dynamic ones due to the kinematics of the machine (Hayati 1983; Zhang et al. 1985; Duffie and Maimberg 1987; Weekers and Schellekens 1995). These errors may be generally classified under two main categories:

• Systematic errors which are completely repeatible and reproducible, and

• Apparently random errors which vary under apparently similar operating conditions.