Overview
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Intelligent Machining: Overview.
The machine tool industry is also benefiting from some of the
factors that are leading to advances in motion control in general. The
need for high-speed and high-accuracy operation is
paramount. Furthermore, the machine tool must maintain this high level
of performance in spite of changes in materials, cutting conditions,
payload, and environmental conditions such as temperature.
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)
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