| 摘要 |
A positioning device positions a driving unit of which a torque constant fluctuates depending on a position, whereby a proper quantization error is obtained even when a maximum current value in a movable range changes. The positioning device includes a position detector for detecting a present position of the drive unit, a control circuit for generating a digital drive command value corresponding to a positional error between a command position and a present position, a D/A converter for converting the digital drive command value into an analog voltage, and a driver, having a plurality of gains, for converting the analog voltage into the analog drive current with a selected gain. The control circuit selects the gain of the driver in accordance with the present position. The gain of the driver (voltage/current converting amplifier) is made variable and controlled corresponding to the position, and hence there is no necessity for covering the maximum current range with the digital command value. Therefore, the proper quantization error is obtained in the entire movable range, and the maximum current value needed in the position is obtained.
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