| 摘要 |
A swivel arm (14), which is operated by a motor (15) driven by a control unit (UC), winds yarn loops forming a weft reserve (RT) on a stationary drum (12). A position detector (20) controls the angular position and the speed of the swivel arm, and comprises an annular permanent magnet (22) which is keyed to the shaft (15a) of the motor and is diametrally magnetized with a sinusoidal distribution of the magnetization. A pair of Hall sensors (24, 26), which are angularly spaced at 90° from each other about the axis of the magnet, are arranged near the magnet for detecting the diametral component of the magnetic field generated by the magnet, and are connected for sending signals to the control unit, which is programmed for calculating the absolute angular position (©) of the motor shaft on the basis of the signals from the Hall sensors. |
