Modeling and adaptive control of a coordinate measuring machine

Although traditional measuring instruments can provide excellent solutions for the measurement of length, height, inside and outside diameters, etc., a coordinate measurement machine (CMM), at least in principle, can combine all these requirements in a single versatile instrument. As they can also be fully automated, linked to a CAD system and/or built into the flexible manufacturing cell, CMMs are widely used in today´s industry. The aim of this paper is to design a stable controller for a 3D coordinate measuring machine in the presence of uncertainties and unknown disturbances. To achieve this task, first a simplified model of the CMM is obtained. After this modeling step, different types of adaptive control techniques are applied to get a suitable and efficient control system. The results are discussed in detail in order to give insight to some common problems in controlling CMMs.