Hierarchical Optimal Force-Position Control of a Turning Process

摘要

Machining process control technologies are currently not well integrated into machine tool controllers and, thus, servo-mechanism dynamics are often ignored when designing and implementing process controllers. In this brief, a hierarchical controller is developed that simultaneously regulates the servomechanism motions and cutting forces in a turning operation. The force process and servomechanism system are separated into high and low levels, respectively, in the hierarchy. The high-level goal is to maintain a constant cutting force to maximize productivity while not violating a spindle power constraint. This goal is systematically propagated to the lower level and combined with the low-level goal to track the reference position. Since the only control signal (i.e., motor voltage) resides at the lower level, a single controller is designed at the bottom level that simultaneously meets both the high-and low-level goals. Simulations are conducted that validate the developed methodology. The results illustrate that the controller can simultaneously achieve the low-level position tracking goal and the high-level force-tracking goal.