A self-tuning adaptive feed-forward control for a retrofit milling machine

✍ Scribed by Shiuh-Jer Huang; Chuen-Chung Chen

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 690 KB
• Volume: 4
• Category: Article
• ISSN: 0957-4158
• DOI: 10.1016/0957-4158(94)90025-6

✦ Synopsis

A traditional manually operated milling machine with a lead screw transmission system is retrofitted to an A.C. servo motor control. This obsolescent milling machine has nonlinear time-varying behavior due to obvious backlash and irregular coulomb friction of the sliding surfaces. If a traditional digital controller is employed, its gain values have to be adjusted corresponding to the system parameters' change by trial and error. In addition, this approach cannot assure the required stability and accuracy of a closed loop system under the enviromental variation of machining operations. Hence, a self-tuning control strategy is proposed for this nonlinear system by introducing an on-line estimator of system parameters to adjust the feedback gains for the desired dynamic characteristics. The conce'pt of Iced-forward control is employed to improve the accuracy of the trajectory tracking control. The experimental results show that this control method achieves satisfactory perh~rmance of stability, transient response, tracking and robustness under the influence of al'~ut 11.4 mm backlash on each axis and large stick friction.