GB1259787A - Phase actuated position determining device - Google Patents

Abstract

1,259,787. Measuring displacement electrically NATIONAL RESEARCH DEVELOPMENT CORP. Oct.8, 1969 [Nov.26, 1968J, No.55949/68. Heading G1Nx. [Also in Division G3] Three flat zig-zag windings 2, Fig.2, are symmetrically interleaved and connected to a 3-phase A.C. supply R, Y, B to produce a linearly developed 3-phase magnetic field which is sensed by a pick-up coil 1. The phase of the voltage signal in coil 1 is determined at 5 by reference to the voltage between the RY phases and is indicative of the position of coil 1 within one pitch of six conductors of the 3-phase winding 2. The particular pitch is determined by counting zero phase positions as coil 1 is moved from one end of winding 2, or a further single pitch 3-phase winding 10, spread over the total range of movement at an angle and having its own pick-up coil 9, enables the pitch position to be determined. The position signals may be compared with signals from a demand device 12, representing a desired position, any difference causing a motor 11 to move coils 1, 9 until the difference is eliminated. The 3-phase winding 21 may be circular in form, Fig.4 (not shown) to measure angular displacement. The 3-phase winding 26, Fig. 3 may be preformed to a shape to be followed by a work tool on a slide 25, attached to the pick-up coil 20. The slide is traversed longitudinally in the direction 22, and the phase of the pick-up signal is compared at 21 with a desired phase, any difference being fed to a motor 23 to move the slide transversely in the direction 24. Alternatively Fig. 5 (not shown), the pick-up coil 41 is traversed longitudinally and the phase of the pick-up signal compared at 42 with that in the rotor of selsyn 46, any difference being fed to a motor 44 to rotate the rotor and a tool attached to shaft 47 until balance is restored.