GB629104A - Improvements in or relating to electrical control systems - Google Patents

Abstract

629,104. Automatic electric control systems. SPERRY GYROSCOPE CO., Inc. Aug. 19, 1942, No. 11671. Convention date, Aug. 19, 1941. [Class 38 (iv)] [Also in Groups XXXVIII and XL (c)] In a position control system, a displacement signal from a controlling member is passed to an amplifier, the D.C. output of which influences the excitation of an opposed field generator supplying power to a servomotor. In the embodiment described the controlling device comprises an electromagnetic pick-off 101 having a central pole supplied with A.C. which is variably coupled, by a suitably-shaped movable member 161, with the outer limbs carrying opposed windings so that the output from the latter windings varies in magnitude and phase with the displacement of the member 161 from the central position. Such a device forms the subject of Specification 629,150. The output is brought into phase with the supply 137 by a phase-shifter 106 and applied to a transformer 105, whose secondary winding 109 feeds the opposed halves of valve 121. According to the phase of the input, one half of this valve passes current on successive half-waves of the supply and, .after smoothing by a tuned circuit 145, 147 the output appears across resistor 141, 143 as a voltage proportional to the displacement of the member 161. The changes in this output pass through condenser 165, 169 and appear as a velocity derivative across resistor 167, 171 which are each further connected through a condenser 173, 181 to give an acceleration derivative output across resistor 175, 183. To this voltage are added controllable amounts of velocity derivative, by resistors 179, 185 and of displacement voltage, by potentiometers 187, 189, and the resultant is applied to a duplex amplifying valve 177. The resultant voltage appears across a resistor 205, 207 directly coupled to duplex triode 223 but, since this is connected to the A.C. supply in the opposite sense, the voltage is made to persist during each subsequent half-wave by charging condenser 217. The final output flows through the appropriate one of the opposed field windings 237, 239 of generator 241, of which the armature is driven at constant speed, by motor 242, to give an output proportional to the excitation. This drives the servomotor 247 which may restore the element 161 by a follow-up action and position any controlled object such as a rudder 251. Specification 539,995 also is referred to.