線性平面步進馬達之運動監控系統

Abstract

線性平面馬達傳統受限於硬體架構，為一Open-Loop的系統。如果沒有位置回授裝置，當動子發生失速與失步的情形時，控制系統會因無法察覺而持續給予命令，進而累積過多的錯誤。這個缺點限制了線性平面馬達的使用與發展，適當的位置感測器及控制技巧可以改進這些缺點。 本文將8051單晶片微處理器控制的超音波感測器裝置於線性平面步進馬達之動子上，利用超音波感測器量測動子至平台邊緣的距離，再透過RS-232界面將值傳入PC，由PC輔以Median Filter及Kalman Filter的訊號處理的方式來提高量測精密度，藉以確定動子在平台上的位置。至於線性平面步進馬達的控制方面，則由PC下的運動命令經由RS-232界面送入8051單晶片微處理器，由8051依運動命令間隔時間送出步進脈波到線性平面步進馬達的驅動器，來控制動子的運動。當運動系統完成運動指令時，可藉由超音波感測之位置，達成監控功能，減少線性平面步進馬達失速之情形。

Traditionally﹐the planar linear motor operates in an open-loop control structure. When the forcer stalls or loses its step command﹐the motion system presents totally inaccurate performance since there is no position feedback. The usage and development of the planar linear motor are thus limited. Such defect can be improved by applying proper position sensors and control. In this study﹐ultrasonic sensors which are controlled by 8051 microcontrollers are set up on the forcer of planar linear motor. The distance between the forcer and the edge of the planar can be then measured and transformed to PC through RS-232.By applying signal process techniques of median filter﹐rectangular window﹐and Kalman filter﹐precision of measurements will be significantly improved and the location of the forcer on the planar could be thus exactly settled.8051 microcontrollers are applied to generate pulse commands to the motor. As the planar linear motor loses its step command﹐the present ultrasonic sensors provide X and Y positions to the control system and necessary modification of command to achieve accurate motion can be thus taken.