Patent GB-892969-A (GB)
Title: High-accuracy gyroscopic apparatus
Inventor: SEDGFIELD HUGH BROUGHAM
IPC: G01C19/38
Filed: 1952-12-02
Abstract: 892,969. Automatic control systems for gyroscopes. SPERRY GYROSCOPE CO. Ltd. Jan. 27, 1954 [Dec. 2, 1952], No. 30572/52. Class 38 (4). In an aircraft navigational system, of the type described in Specification 826,417, in which the instantaneous craft position on the earth's surface is computed and in which allowance is made for the earth's rotation, a platform is stabilized by means of three gyroscopes mounted thereon. Two of the gyroscopes define the vertical and horizontal axes respectively while the third has its spin axis horizontal and is adapted to permit the direction of rotor rotation to be periodically reversed. The average rate of wander of the reversible gyroscope is zero and it is used as a primary direction-giving instrument for setting and monitoring the first horizontal gyroscope. General operation.-As shown, Fig. 4, the platform 7 is stabilized about the axes GH, EF by the vertical gyroscope 10, horizontal gyroscope 11, and the accelerometers 45, 46, 91. The electrical error signals from the accelerometer outputs are applied to the computer 100, where allowance is made for the earth's rotation. The platform is positioned by servomotors 30, 32, 34, controlled by the gyroscope and accelerometer signals. In order to compensate for wander of gyroscope 11, the rotor of the similar gyroscope 12, carried on 7, is periodically reversed, the relative displacement between 11 and 12 is electrically detected and the resultant signal used to process 11 and neutralize the wander. Operation of reversible gyroscope.-The relative displacement between 11, 12 is detected by the pick-off 6 and 6<SP>1</SP>, the outputs of which are applied differentially to the signal channel separator and storer 104. The input to 104, which is supplied through either switch 105 or 106 according to the direction of spin of the rotor of 12, is integrated during each spin period and stored by 104. Two outputs are provided from 104, viz. the sum and the difference of the stored, integrated inputs. The sum output, a function of the wander rate of 11 is supplied continuously along 107<SP>1</SP> to the torque motor 41. The difference output, a function of the wander rate of 12 is supplied along 112 to torque motor 41<SP>1</SP>. The reversing gyroscope 12 is brought to a predetermined angular position with respect to 11 before beginning of each spin period by the misalignment signal applied through switches 109, 110 to torque motor 41<SP>1</SP>. Storing device,-As shown, Fig. 8, the input signals from the pick-offs 6, 6<SP>1</SP> of gyros 11, 12 cause rotation of motor 132 during the forward spin period of 12 and of motor 133 during the reverse spin period. The motors control the position of wiper arms 137, 138 and the rotationally variable transformers 139, 140 which feed back to the input of amplifier 103. The outputs from 137, 138 are applied to the summing and difference circuit 152. In a modification, not shown, the storing and integrating is effected thermionically. The signals from pick-offs 6 and 6<SP>1</SP> are applied to an amplifier the output of which is a measure of the input voltage plus the time integral of the input voltage and is applied to cathode follower storage circuits. Specifications 732,975, 740,349, 804,847 and 804,849 also are referred to.