Machine tool control systems, as a special class of motion control systems, also have several additional considerations, these of which are particularly noteworthy. THe first consideration is that precise motion must be maintained where large forces are involved. Consequently, the systems are designed to be more physically robust. The control designer must obtain a good model and maintain contouring accuracy despite the system loads, the large masses involved, and the presence of friction. The second consideration is the integration of the machine tool into a larger computing environment. Critical data flows into and out of the machine tool controller. For data coming to the machine tool, the transformation of part geometries into path commands is critical. For data leaving the machine tool, reporting status and error conditions are critical. The third consideration is the accommodation of control modules that actively monitor and adjust the cutting force in order to achieve a high quality surface finish. In such a system, position reference commands passed to the servo axis controllers must be modified in real time. Foe these reasons, the architecture and design of the machine tool controller and the relation of the controller to the low-level servo system is a current research topic, and open architecture controllers have gained popularity in recent years.

Our research in this area hopes to address these issues, both the low-level servo-loop design and the higher-level controller architecture and path generation. (M. Tomizuka, ILP Summary 1996-1997)