Patent GB-1203841-A (GB)
Title: Gyroscopic instruments
IPC: G01C21/18
Filed: 1968-01-01
Abstract: 1,203,841. Gyroscopic apparatus. TOKYO KEIKI SEIZOSHO K.K. Jan.1, 1968 [Jan.13, 1967], No.66/68. Heading G1C. A gyroscopic instrument for determining the meridian plane and the latitude at a location comprises a case having a rotar mounted therein for rotation about an axis orthogonal to the plane of the figure, the case 4 being supported with three degrees of freedom and a torquer 17 for applying a control torque to the case 4 about a substantially horizontal axis defined by shafts 7, 7<SP>1</SP> in response a differentiated valve of the inclination of the spin axis to the horizontal, whereby the spin axis will be brought into alignment with the meridian by the normal action of a gyro compass, and the inclination thereof to the horizontal will indicate the latitude. The case 4 is mounted for rotation in bearings B 1 , B 1 <SP>1</SP> in a ring 6, the ring 6 being carried by the shafts 7, 7<SP>1</SP> for rotation in bearings B, B<SP>1</SP> in a container 8 containing a flotation fluid e.g. transformer oil to substantially relieve loading on the bearings B, B<SP>1</SP>, B 1 , B 1 <SP>1</SP>. The container 8 is carried in bearings B 2 , B 2 <SP>1</SP> in a ring 12, this ring being mounted for rotation about an axis normal to the plane of the figure in a vertical follower ring 13, in turn mounted in bearings B 3 , B 3 <SP>1</SP> in a support ring 14 fixed to a base 10. The container 8 is rendered pendulous by the addition of a weight 21 thereto, otherwise the pivot axis defined by the bearings B 2 , B 2  may be disposed above that defined by the shafts 7, 7<SP>1</SP>. A pick-off 18 detects relative displacement between the case 4 and ring 6, and the output of this pickoff controls a servomotor 26 which through gearing 22, 23, 24, 25 rotates the follower ring 13 and thus the ring 6 back into correspondence with the directional reference given by the gyro rotor spin axis. The upper shaft 9<SP>1</SP> of the ring 13 carries a compass card 29 which when read against a pointer 28 indicates the azimuth. A device 16 is mounted for rotation an the shaft 7<SP>1</SP> of the ring 6 and this device contains a gravity reference in the form of an electrolytic switch controlling an electric servomotor which rotates the device 16 to bring the electrolytic switch back to its level position. Thus the device 16 remains stationary whilst the shaft 7<SP>1</SP> rotates due to the action of the electrolytic switch. The output of this switch, and thus the speed of rotation of the associated servomotor, depends on the deviation of the position of the switch from the level, and thus this signal is proportional to the differential of the inclination of the gyro rotor spin axis from the horizontal, and is fed to the torquer 17 to apply the desired control torque to the case 4. A similar torquer connected in parallel with the torquer 17 may be mounted about one of the shafts 5, 5<SP>1</SP> of the case 4 to improve the performance of the instrument. A synchro, or poteniometer may be connected to the servomotor of the device 16 to give a signal indicative of the inclination of the rotor spin axis to the horizontal i.e. the latitude. The use of accelerometers in phase of the electrolytic level in the device 16 is described and in further alternative arrangements the torquer 17 is dispensed with and the device 16 replaced by a weight or pair of inter-connected liquid-filled pots pendulously mounted about the shaft 7<SP>1</SP>.