Patent GB-825919-A (GB)
Title: Improvements in and relating to gyroscopic apparatus
IPC: G01C19/38
Filed: 1956-04-19
Abstract: 825,919. Gyroscopic apparatus. ABBEY, A. (American Bosch Arma Corporation). April 19, 1956, No. 40063/57. Divided out of 825,917. Class 97(3) [Also in Group XXXV] Gyroscopic apparatus includes a selfsychronous transmitter having stator windings connected to a Scott-connected auto-transformer. The application described is to a gyro-compass of the kind described in Specification 825,917, which is shown diagrammatically in Fig. 1. Operation is as follows: if the gyro spin axis is displaced from the meridian, its easterly end will apparently rise as the earth rotates, causing gimbal ring 14 to be displaced with respect to the sensitive element 11. This results in a signal generated in the windings of pick-off 43, which are of the "umbrella" type described in U.S.A. Specification 2,677,194, being applied to motor 111, which drives gimbal ring 86, tank 10 and gimbal 14 until ring 14 is again co-axial with the sensitive element. As the tank has been tilted, the pendulum armature 120 is displaced relatively to its pick-off 122, and a signal is generated which is applied to motor 111 to drive the gimbal ring away from the sensitive element, twisting the wires 15, 16 which apply torque to the sensitive element to cause it to precess towards the meridian. By choice of the output polarities of pick-off 43, 122, the compass may be made either pendulous or anti-pendulous, the direction of rotation of the gyro being chosen accordingly. As the sensitive element precesses toward the meridian, follow-up action between a pick-off 44 and motor 105 tends to keep the axis of shaft 87 aligned with the gyro spin axis. A portion of the output signal from pick-off 122 is also applied to motor 105 to produce a slight displacement between tank 10 and sensitive element 11, whereby wires 17, 18 are twisted to apply torque to the sensitive element to precess the gyro axis towards the horizontal, thus applying vertical damping to the gyroscope. As described in U.S.A. Specification 2,677,194, the speed and course error is corrected by applying a torque equal to H/R -S 0  cos C 0  about the vertical axis by means of torsion wires 17, 18, and the latitude error is corrected by applying a torque equal to HW sin # about the horizontal axis by means of torsion wires 15, 16; where H is the angular momentum of the gyro rotor, R is the radius of the earth, S 0 , C 0  are the speed and course respectively of the vehicle carrying the compass, W is the angular velocity of the earth's rotation, and # is the latitude of the vehicle. The speed and course error correction torque is derived as follows. A transmitter 115, Fig. 2, has a rotor 130 connected to the pivot shaft 112 of the frame 100 and energized by a constant alternating voltage, and stator windings 131 connected to the 3-phase terminals of a Scott-connected auto-transformer 132. The output of the auto-transformer is proportional to the cosine of the displacement of frame 100, i.e. to the cosine of the course angle C 0  This signal is multiplied by H/R in voltage divider 136; and by the speed S 0  in variable voltage divider 137, the controlling shaft 138 of which is displaced manually or automatically in accordance with the speed S 0 . The output of voltage divider 138 is thus proportional to H/R S 0  cos C 0 . Specifications 825,918 and 825,920 also are referred to.