GB500652A - Improvements relating to follow-up systems for sensitive indicators - Google Patents

Abstract

500,652. Electric signalling systems. systems. SPERRY GYROSCOPE CO., Ltd., HARDING, W. G., and NISBET, R. H, June 14, 1937, No. 16487. [Class 40 (i)] A repeater or other object is driven by a servomotor controlled in part by an instrument the position of which is to be reproduced, and in part by a follow-back from the servomotor, corrections for errors in the indications of the instrument being introduced in the follow-back. In Fig. 2, the follow-up member of a gyro - compass operates a selsyn transmitter 2. The signals are applied to the rotor of a selsyn receiver 5<1> and the voltages induced in the stator control a servomotor 34 which drives the shafts 6<1> and 6 so that the shaft 6 carrying the rotor of 5<1> follows the transmitter. A worm on the shaft 6<1> drives a compass card 12 associated with which is a device for automatically determining the Northsteaming error and moving a rack 20 a vertical distance in proportion to the error. The rack 20 engages a differential 33 connecting the shafts 6 and 6<1> so that the movements of shaft 6 and rack 20 are added. A reversing gear 85 enables both the shafts 6 and 6<1> to turn in the same direction. An amplifier 37 suitable for connection between the receiver 5<1> and the servomotor 34 is described in Specification 417,995. A synchronizing device 38 is also provided to enable the indications of the follow-up member and the uncorrected indications of the compass card 12 to be brought into agreement initially. A fixed pointer 13 and a moving pointer 29 give corrected and uncorrected readings respectively. In the modification shown in Fig. 4, the servomotor is controlled as in Fig. 2, but the correction is introduced in the follow-back by arranging the shafts 6 and 61 on different axes so that compass cards 12 and 12<1> are eccentric. A lever 57 can be adjusted relative to the card 12 by a screw 58 and carries a pin 56 which engages a radial slot in the compass card 12<1>. The correction introduced for " damping error " is controlled by the screw 58. Ships' speed and latitude are allowed for by moving the receiver 5<1> in slides 66 and 67 to vary the eccentricity of the connection between cards 12 and 12<1>. In a modification, similar to that shown in Fig. 4, the transmitter 2 and receiver 5<1> are of the step-by-step type and the pin 56 and slot arrangement are replaced by electrical contacts which cause current to pass in one direction or the other through the servomotor 34 according to the direction of rotational displacement of card 12 relative to card 12<1>. Correction for North-steaming error may be applied as described in Specification 461,424, [Group XX]. Specifications 500,647 and 500,648, also are referred to.