Control design for tracking performance in machine servo systems

Modern motion control systems, such as laser cutting machines, milling machines, and semiconductor manufacturing equipment, are required to achieve high precision and high speed simultaneously. However, the precision of such machines is often limited by the increasing cutting speed.; The research performed for this dissertation evaluates different control design methods, and the resulting controller structures, based on the tracking performance for a linear motor system (LMS) and a gantry style machine system (GSMS). The best control structure for the linear motor system and the gantry style machine system is chosen. Proper design techniques for these structures are described in detail.; The contributions made to control engineering presented herein include a modern interpretation of classical loop shaping control design method, a PID tuning procedure based on this interpretation, a novel feed forward control design method (RCLI), and a comparison between PID loop shaping control design and three feed forward control design techniques.; A classical loop shaping control design method, three feed forward control techniques, and a H_∞ loop shaping design method are presented in the context of tracking control for the linear motor system. The three feed forward controllers are velocity and acceleration (V&A) feed forward controller, the zero phase error tracking (ZPET) controller, and the reduced order closed-loop inverse (RCLI) controller. Laboratory results from the linear motor system demonstrate that with large open loop gains a PID controller, or a V&A controller combined with PID, very good tracking performance can be achieved.; Three types of control are used for the gantry style machine system. They are single linear motor control (SLMC), two linear motor control (TLMC), and master-slave (MS) control. Laboratory results from the gantry style machine system show that TLMC can achieve very good tracking performance just like a linear motor system.; V&A combined with PID is the best controller for tracking performance for the linear motor system and the gantry style machine system. Pure PID with large open loop gains can also achieve good tracking for both systems. These two controllers are robust and simple to implement. The design methods are also applicable to many electromechanical servo actuators other than linear motors.