Machining, Measurement, and Control Laboratory

2 0 0 0    J o u r n a l    P a p e r

Design of linear motor servo systems under the influence of structural vibrations
--Stabilizing controller design based on state feedback--
Atsushi Matsubara
Yoshiaki Kakino
Kazunori Sakurama

Linear motor feed drives are considered as an ideal drive with no transmission, no backlash and smooth motion. However, if they are applied to dynamically complicated machines such as machining centers and cantilever-type XY robots, servo control systems are influenced by structural vibrations. The vibrations inspired by tracking motion aggravate the motion accuracy, which could result in the instability of the servo control loop. This paper presents a design method of stabilizing controllers for linear motor servo drives under the influence of structural vibrations. The feed drive system is modeled and analyzed by taking structural vibrations into account, and then stabilizing controllers are designed based on modern control theories. A reduced-order controller is also designed and compared with classical PI compensators in terms of servo characteristics. Observer-based full-state feedback controller and local state feedback controller are found to achieve preferable performance in numerical simulation and experimentation.

Key words: linear motor, feed drive, stabilizing controller, modern control theoryCrobust servo

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