Patent GB-619960-A (GB)
Title: Improvements in or relating to gyro-verticals
IPC: G01C19/44
Filed: 1946-03-13
Abstract: 619,960. Automatic control systems for gyroscopes. STEVENS, A. H. (Sperry Gyroscope Co., Inc.). March 13, 1946, No. 7914. [Class 38 (iv)] [Also in Group XX] Relates to gyro verticals having gravitycontrolled erection devices of the type in which the magnitude of the erecting torque is substantially independent of the relative displacement between the gyro and the gravity controller and having the axis of total angular momentum directed at a small angle to the vertical to correct for acceleration errors during turning. To correct the turn errors for all rates of turn, means is provided for adjusting the relationship between the horizontal component of angular momentum and the control effect exerted by the erection device while the gyrovertical is in operation. Preferably a rate of turn gyroscope is arranged to vary the control effects exerted by the erection device, the rate of spin of the rotor of the gyro-vertical or of an auxiliary rotor mounted on the gyro casing, or the tilt of the gyro-vertical. In the form shown in Fig. 1 the gyro is erected into a position in which its spin axis makes a constant angle a with the vertical in the fore-and-aft plane by torque motors 14, 15, controlled by the amplified outputs of transformer pick-offs 9<SP>1</SP>, 101, associated with pendulums 9, 10 pivoting about fore-and-aft and transverse axes respectively on the rotor casing 1. The pendulums 9, 10 are allowed to swing freely through, say 2 degrees, the erecting torques being then proportional to the displacements of the pendulums. Thereafter the pendulum movement is limited by one or other of the stops 12<SP>1</SP>, 12<SP>11</SP>, and the erecting torques are constant. The erection rate of the torque motor 14 is varied in accordance with the rate of turn of the craft by a rate of turn gyroscope 16, which operates through a cam 19 and follower 23 to move a contact 21 and thereby alter the amount of resistance 22 included in the supply circuit to the transformer 9<SP>1</SP>. When the rate of turn corresponds to an angle of bank of less than, say, 2 degrees, the contact 21 moves on a conducting strip 22<SP>1</SP> and no adjustment is effected. In a modification in which the speed of rotation of a single tilted rotor is varied, the resistance controlled by the rate of turn gyroscope is in circuit with the shunt field of a D.C. motor, so that the latter rotates at a speed inversely proportional to the rate of turn. The D.C. motor drives a threephase A.C. generator which, in turn, drives the motor incorporated in the gyro rotor. In order that variations in the resistance may not take place for rates of turn less than a predetermined amount, the follower 23 is arranged to be out of contact with the cam 19 near the latter's zero position. The predetermined amount may be varied in accordance with the linear speed of the craft by an adjustment in the position of the resistance. When the horizontal component of angular momentum is provided by an auxiliary gyroscope, the rate of spin of the latter may be varied in a similar manner. In a further modification in which the tilt α of a single gyro is varied inversely with the rate of turn, the signal from a pick-off of the type shown at 101 is combined with a separate signal controlled by an automatically varied resistance such as that at 22, the effect being to shift the point of zero resultant signal and to adjust the settling point of the gyro accordingly. A pitch index to co-operate with the lines 7 is displaced by linkage connected to the follower 23 to compensate for the variations in the tilt of the sphere 5. A similar correction is applied to a transmitter on the transverse trunnion of the .gyro by adjusting the position of the stator of the transmitter by a motor which repeats the movements of a shaft suitably geared to the follower 23. Specification 619,939, [Group XX], is referred to.