GB984584A - Improvements in automatic control systems - Google Patents

Abstract

984,584. Automatic control. BENDIX CORPORATION. Nov. 29,1961 [Dec. 1, 1960(2)],No. 42706/61. Heading G3R. In a servomotor control system A.C. and D.C. control signals are applied in series to a demodulator supplied from a source having the same frequency as the A.C. signal and the resulting D.C. output signal is combined with the output of a tachometer generator driven by the servomotor in an interspersed double modulator arrangement which produces an A.C. signal to control the servomotor. Arrangements for the automatic control of ailerons and elevators of an aircraft are described. In Fig. 1 A.C. signals from the roll pick-off 11 of a gyro 10 are combined in series with square wave output signals from a VOR or localiser radio beam receiver 17, and D.C. signals from turn and roll trim potentiometers 13, 14. The combined signals are applied to a switching transistor 21, controlled through a transformer 22 by an A.C. mains source having a frequency equal to that of the A.C. and square wave signals, so that a condenser 25 is charged to a voltage dependent on the combined signals. This direct voltage is converted to pulse form by a switching transistor 26, controlled by the output of a mains transformer 43, and combined with the pulse output of a switching transistor 40 operating on the integrated voltage of a tachometer generator 35 associated with aileron drive 32. Switching transistors 26 and 40 operate 180 degrees out of phase so the two sets of pulses are interspersed and a square wave resultant signal produced corresponding in phase sense and magnitude to the direction and extent of necessary positional correction of the ailerons. This resultant signal is applied through a pushpull high impedance input transistor amplifier 31 to a demodulator 48 which energizes one or other of clutches 67, 68 to move the ailerons in the appropriate direction. A rectifier 51 introduces an amplifier dummy load 50 and rectifiers 63, 65 complete discharge paths for the clutch coils during non-conductive half cycles of demodulator 48. In addition, in a modification, A.C. signals from the pitch pick-off of a gyro are combined with square wave output signals of a glide path radio receiver, and D.C. signals of an automatic pitch trim potentiometer, to control the elevators through a system similar to that controlling the ailerons.