GB772090A - Improvements in or relating to gyromagnetic compasses - Google Patents

Abstract

772,090. Electric gyro compass systems. SMITH & SONS (ENGLAND), Ltd., S. July 14, 1955 [July 16, 1954], No. 20853/54. Class 40 (1). A compass system comprises a gyro controlling the angular position of a first shaft directly and a second shaft through a differential selsyn link which may be preset for a given craft bearing, the angular position of the second shaft being compared with the bearing as given by a magnetic compass, whereby any discrepancy may be used to process the gyro except when the rate of turn of the craft is excessive, or when the magnetic compass is unreliable. As shown, the heading of a craft as determined by the gyro 1 which positions the rotor of a selsyn device 3, is indicated by a shaft 5 attached to the energized rotor of a further selsyn 6, the stators of selsyns 3 and 6 being connected to a differential selsyn 8 whose windings are manually settable, so that any discrepancy between the angular positions of the rotors of 3 and 6 produces a signal in the rotor of selsyn 3 which is amplified at 9 to energize motor 7 to reposition shaft 5, and the rotor of selsyn 6 to eliminate the error signal. A further shaft 10 is also brought into positional agreement with shaft 5 by a selsyn 11 whose stator is connected to that of selsyn 6, error signals being amplified at 12 to energize motor 13 to drive the shaft 10 and rotor of selsyn 11 to eliminate the error signal. The heading of the craft is also determined by the magnetic detector 14, and is compared at 15 with the angular position of shaft 10, indicating the heading as determined by gyro 1, any discrepancy appearing as a signal, amplified at 16 and energizing torque motor 2 through switches 17, 18 to precess the gyro 1. When the rate of turn in azimuth exceeds a predetermined value, a rotation-sensitive switch 21 on shaft 10 closes contacts to energize relay 22 to open switch 18, and also energizes relay 23 which opens a switch 24 in an alarm circuit. The above system is duplicated at 100 and a selsyn 20 attached to each shaft 5 give a discrepancy signal when they disagree which is amplified at 28 to energize a relay 29 to close switch 30 in the alarm circuit. Switch 17 is manually operable to disconnect the magnetic detector 14 when unreliable, e.g. in polar regions. Specification 586,506 is referred to.