| 摘要 |
In a screened inductance sensor system having a drive winding (18) energisable to set up an alternating magnetic drive field, a sense winding (20) links the drive field and a screening element (13) modulates the spatial distribution of the drive field, when in the vicinity of the sense winding (20). Variations in voltage induced in the sense winding (20) provide an indication of the relative position of the screening element (13) and the sense winding (20). The drive winding (18) and the sense winding (20) are accommodated in a displaceable portion (15) of the sensor, and the screening element (13) is fixedly located relative to the movable sensor portion (15). Modulation of the spatial distribution of the drive field occurs when the displaceable sensor portion (15) is moved into the vicinity of the screening element (13). In application of the system to control of vehicles (12) following a predetermined path, fixed screening elements (13) may be located at spaced apart intervals along the path, where the vehicles (12) are on tracks, to provide locational signals according as the vehicles (12) pass these fixed screens. The system may also be applied to providing guidance and position information for a steerable vehicle, in which case two sense windings are used, one responsive to sidewise deviation from the intended path of travel, and the other sense winding providing a cycled output signal, which is counted to yield a measure of distance travelled.
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