Patent GB-917168-A (GB)
Title: Gyroscopic reference apparatus
IPC: G05D1/08
Filed: 1959-09-25
Abstract: 917,168. Measuring electrically. SPERRY RAND CORPORATION. Sept. 25, 1959 [Oct. 13, 1958], No. 32708/59. Class 40 (1). [Also in Group XXXV] In gyroscopic apparatus two gyroscopes defining an azimuthal reference direction are maintained with their spin axes mutually at rightangles, any tendency of either gyroscope to deviate from the required configuration being detected and processing torques applied to both gyros to precess them in opposite directions to reduce the deviation to zero. The gyros spin axes are maintained horizontal by conventional level sensor end torque motor arrangements and roll and pitch signals derived from transducers attached to the gyro gimbals, the transducer outputs being fed through a resolver adjusted according to the azimuth heading of the craft in order to obtain the roll and pitch of the craft in terms of the craft co-ordinates rather than space co-ordinates. Gyro arrangement, Fig. 1. Gyro rotors 29 and 37 are each mounted via two pairs of gimbals on the aircraft frame 13. Gyro rotors 29 and 37 are mounted in inner gimbals 27 and 35 and these gimbals are maintained horizontal by means of level sensors 46 and 48 feeding torque motors 47 and 49. In order to maintain the spin axes of the gyros at right-angles, gimbals 25 and 33 are attached to the rotors of synchros 60 and 61 whose stators are attached to gimbals 24 and 32, respectively. Deviations of the spin axes of the gyros from the required 90 degrees configuration result in a signal output from the rotor of synchro 61 which is fed via amplifier 62 to torque motors 63 and 64 to precess both gyros in opposite directions to reduce the deviation to zero. In addition the common stator signal of synchros 60 and 61 is fed, as the azimuth signal to a resolver 65, the output of which drives motor 66 via amplifier 67 to align the rotor of the resolver 65, and hence the compass card 72 and resolver 51 to the azimuthal heading, feed-back over the motor-amplifier combination being provided by rate signal generator 71. Synchro transmitters 50 and 53 give output signals corresponding to the components of the tilt of the axes 20 and 26 of the gimbals 24 in the directions of the spin axes of the two gyros, these signals are fed via amplifiers 52 and 54 to resolver 51 from which the pitch and roll error signals are derived and fed via amplifiers 73 and 83 to motors 74 and 82 which drive gimbals 14 and gimbals 24 and 32 to eliminate the error signals from synchros 50 and 53. Motor 74 driving gimbal 14, and synchro transmitter 80, until the gimbal is horizontal, in which position synchro transmitter 80 gives a signal corresponding to the roll output, and motor 82 driving gimbals 24 and 32, which are mechanically coupled together and to synchro 86, until they are vertical, in which condition synchro 86 produces a pitch output signal. Also coupled to the vertical gimbals 24 and 32 is a potentiometer 88 from which is derived a pitch correction signal to feed the roll amplifier 73. Feed-back is provided on both motors 74 and 82 via rate generators 75 and 84, the output from which are fed to the respective amplifiers. Specification 917,169 is referred to.