| 摘要 |
PURPOSE:To maintain the stable levitation state of a conveyor by converting photodetection amounts from a plurality of optical gap sensors into air gap length signals, and determining an exciting current on the basis of the smallest air gap length signal thereof. CONSTITUTION:Even if one gap sensor 34a arrives at the seam of guide rails 12a (12b) in the moving process of a conveying vehicle, the other gap sensor 34b is disposed at a position separated from the seam. Thus, the two sensors 34a, 34b are not simultaneously affected by the influence of the seam. Since the detection signal of the sensor 34a which is not affected by the influence of the seam is selectively introduced by a selector 66 to a calculator 67, an electromagnet 51 is not energized more than required. Thus, even when the vehicle passes the seam of the guide rails, it can obtain a stable magnetic levitation state.
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