GB924093A - Improvements in gyro-stabilized platforms - Google Patents

Abstract

924,093. Automatic control systems for gyroscopic apparatus. LITTON INDUSTRIES Inc. Aug. 19, 1959, No. 28299/59. Class 38 (4). [Also in Group XX] A platform is automatically stabilized in attitude by two two-degree of freedom gyros having one sensitive axis in common, the platform being effectively set to the mean of two positions about this axis demanded by the two gyros when these differ due to drift. In Fig. 1, two gyroscopes A, B (not shown), having their spin axes horizontal and mutually perpendicular, are respectively mounted each for two degrees of freedom in boxes 12, 13 attached to a platform 11 which is rotatable relative to a member 18 supported in gimbals relative to the structure 14 of a moving vehicle. Amplified signals from a pick-off associated with the vertical axis of gyro A control a servomotor 35 which operates to maintain platform 11 fixed in azimuth. Amplified signals from a similar pick-off associated with the vertical axis of gyro B, which may have drifted in azimuth differently from gyro A, are applied to precess gyros A, B in opposite directions towards a common position in azimuth. Signals from pick-offs associated with the other axes of gyros A and B are suitably modified and combined by a resolver 48, operated by movements of the vehicle in azimuth, so that when applied, after amplification, to servomotors 37, 40, platform 11 is maintained fixed in space relative to the roll and pitch axes of the vehicle. Tilt of platform 11 relative to gimbal ring 17 is eliminated by applying amplified signals from a pick-off 49, responsive to such tilt, to a servomotor 42 to move outer gimbal ring 16. Coarse and fine synchros 45, 46 associated with platform 11, synchro 50 associated with gimbal ring 17, and synchro 51 associated with gimbal ring 16 produce signals corresponding to the attitude of the vehicle about the three mutually perpendicular axes defined by platform 11. The outputs of accelerometers 30, 31, 32 measuring accelerations in the directions of the three axes may be integrated to compute velocity and/or position of the vehicle and these signals may be combined with signals representing the velocity of the earth and utilized to torque the gyros so that the platform is maintained fixed relative to the earth vertical as the vehicle moves over the earth's surface.