| 摘要 |
An automatic gate operator includes an electric drive motor coupled by a drive train to a movable gate, and includes provision for measuring the coasting distance which the gate moves after shut off of the drive motor. This coasting distance varies both with the weight and momentum of the gate in comparison to frictional drag of the gate hardware, and the drag provided by the gate operator with the drive motor shut off, and also varies in response to a great number of other variables many of which are unpredictable. These other variables include such factors as wind, weather, temperature, wear, adequacy of lubrication, time interval since last operation of the gate operator, and off-level installation of the gate, for example. However, the coasting distance is measured and recorded, and is subsequently used as a predictor of gate coast on subsequent operation of the gate operator in order to coast the gate to a stop precisely at a selected limit position. The prediction improves with experience, and compensates over time for progressive changes in the operating circumstances and conditions of the gate.
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