GB1318872A - Stabilized platform - Google Patents

Abstract

1318872 Gyroscopic apparatus SPERRY RAND Ltd 25 June 1970 [26 March 1969] Heading G1C A stabilized platform for providing attitude and heading information in an aircraft comprises two rate gyroscopes 11, 12, each having a rotor acting as a two degree of freedom positional gyro, in a gimbal system with universal freedom, to provide a stable space reference by virtue of its angular momentum, each rotor having sensors to detect rates of deviation of its axis from an initial position, to supply signals which are used to control torque motors mounted on the gimbal system to apply torques to the gyros to counteract said deviations. The gyroscopes are mounted on a frame 15 supported relative to an axis 20 by inner and outer gimbal rings 16, 18, a servo 22 and syncho 22' acting to maintain the ring 18 and the frame 15 aligned to avoid gimbal lock. A chain 57 of resolvers and synchros having a differential drive 61 resolves various signals according to the instantaneous relationship between the gyro axes and the aircraft heading. Synchro/ torquers 33, 33' on the frame 15 sense orientation of the gyros relative to the frame 15 and supply signals via lines D, G and synchro transformers 55, 55' to a summing amplifier 56 which controls a servomotor 61 to move the chain 57 so that the zero points of transformers 55, 55' are adjusted to give zero output, the chain then being adjusted to a correct heading angle derived from the gyros. The outputs of transformers 55, 55' are also applied to summing and difference amplifiers 54, 54' together with azimuth rate signals from the gyros via lines A, C, the modulated outputs being applied through a resolver 50 to torque motors 27, 35 to maintain the gyro axes mutually perpendicular and to correct drift of the gyros axes in azimuth. Tilt of the gyros is sensed by liquid levels 23, 24 whose outputs in lines H, L are combined with an input J (as correction for the angular velocity of the aircraft over the earth's surface) and inputs from a resolver 60 giving correction for the earths rotation, resolved by a resolver 51, and applied to amplifiers 58, 58' together with vertical rate signals in lines B. P. The amplifier outputs 58, 58' are applied via compensation transformers 52, 52' and the synchro resolvers 55, 55' to the torquers 33, 33' to reduce the tilt to zero. A correction for the azimuth component of the earth's rotation is applied to differential 61 to affect only synchros 59, 59', from which synchros heading information is taken for heading indicators or navigation equipment. Synchros 26, 26' on the outer gimbal ring 18 supply pitch and roll information. The gyros are preferably of the type in which the rotor is formed by one or more tubes of fluid with their axes parallel to the spin axis, pressure transducers in the tubes measuring the rate of movement of the spin axis.