GB791987A - Navigation aid apparatus - Google Patents

Abstract

791,987. Automatic steering control systems. SPERRY RAND CORPORATION. July 15, 1955 [Aug. 2, 1954], No. 20544/55. Class 38 (4). In a system for steering an aircraft towards and along a radio beam, the ratio of the magnitudes of signals representative of heading deviation and displacement from the beam is increased when displacement from the beam is reduced below a predetermined value. As shown, a visualomni-range radio receiver 10 in an aircraft produces a D.C. signal dependent on lateral displacement of the aircraft from a course having a bearing determined by a selector 12 relative to the transmitting station. This signal, which is converted into an A.C. signal in a modulator 16 and amplified at 18, controls a motor 20 which, by virtue of a follow-up potentiometer 26, takes up a position dependent on the displacement from course, so that a corresponding signal derived from a potentiometer 32 driven by the motor is applied through a potential divider 34 and amplifiers 38, 58 to turn the aircraft towards course by operating on the bank channel of an automatic pilot (not shown). The followup system 14 tends to smooth out transient effects and a control term dependent on rate of change of displacement is introduced from a generator 22, driven by motor 20, through a potential divider 40 to amplifier 38. The magnitude of the signal applied to the bank channel of the automatic pilot is limited by a diode arrangement 56. The course of the aircraft is also corrected by applying a signal from a synchro pick-off 46 associated with a gyrocompass 44 through synchros 48 and 50 to amplifier 38 so that any deviation of the aircraft from a heading determined by the setting of synchro 50 results in course correction. When the aircraft is substantially on course so that motor 20 closes contacts 84, 86 and a relay 90 is de-energized in the absence of course correcting signals, a relay 80 changes over from the position shown so that (a) contacts 36 reduce the course displacement signal from potential divider 34, (b) contacts 42 increase the rate signal from potential divider 40, (c) contacts 64 reduce the bias of diode arrangement 56 so that the limiting value of the bank signal is reduced, (d) contacts 68 apply the displacement signal through an amplifier 72 to operate an integrating motor 74 which positions synchro 48 so that the heading signal is modified by persistent lateral displacement from course to counter the effect of cross-winds. During the time that the aircraft is seeking its proper course, before relay 80 operates, contacts 68 connect the output of a potentiometer 66 driven by motor 74 to the input of amplifier 72 so that synchro 48 is maintained in a zero position. During banking, relay 90 also serves to disable a gyro-vertical of the automatic pilot. A relay 96 switches in the control system automatically during the initial approach. Specification 647,469 is referred to.