GB599826A - Improvements in or relating to means for controlling the orientation of gyroscopes and other rotating masses - Google Patents

Abstract

599,826. Automatic control systems for gyroscopes. PHILPOT, J. ST. L., and MITCHELL, J. H. June 2, 1945, No. 13923. [Class 38 (iv)] [Also in Group XX] The signals produced in pick-off devices associated with a gyroscopic body mounted upon the rotary member of a gyroscope to spin therewith are responsive to oscillations set up in said body when the spin axis is deflected relative to space axes (see Group XX), and provide forces which precess the rotary member to counteract wander of the spin axis away from said space axes or to feed back energy to the oscillating body to vary artificially the damping of the oscillations of the body so as to produce signals which are indicative of the magnitude of the deflection. As shown in Fig. 11, the gyroscopic body 112 is a bar of rectangular section mounted to rotate with rotor 111 of a gyroscope and is associated with two capacity type pick-off devices 113, the signals from which being fed to the input of an alternating current bridge circuit 115 energized from an oscillator 116 at a carrier frequency, e.g. 5 kc./sec. The bridge is balanced when the body 112 does not oscillate, but on oscillation the bridge 115 will be repeatedly unbalanced at the oscillation frequency resulting in an output from the bridge 115 of the carrier frequency modulated at the oscillation frequency which is adjusted to be the .same as the spin frequency. This output is treated in amplifier 117 and demodulator 118 to provide an output at oscillation frequency which is applied to precess the gyroscope about inner and outer gimbal axes respectively, e.g. the output is applied to one of the phases of two torque motors 119, 120 of two-phase excitation type. The second phase of the excitation of motors 119, 120 is obtained from a generator 121 driven at a speed proportional to or at the same speed as rotor 111, amplified in 122 and phase adjusted in 123. In Fig. 6, a bar of magnetic material is used as the gyroscopic body 62, the rotor carrying beneath one end of the bar a capacitative pick-off device 63 and beneath the other end an electromagnet 64. Signal output from 63 is fed via slip ring 65 to an oscillatoramplifier 66 which is responsive to capacity change at its input and its output is fed back in proper phase to the body 62 via electromagnet 64 to reduce even to a negative value the effective damping according to the gain of amplifier 66. In a modification (Group XX), employing an annular disc as the gyroscopic body, the pick-off devices or pick-off devices and electromagnets arranged alternately are stationary and disposed around the spin axis on the gyroscope rotor casing. A suitable bridge circuit for 115, Fig. 11, is shown in Fig. 3 (Prov.), wherein the pick-off capacities 113, Fig. 11, are balanced against each other in the first arm 8 of the bridge 3, 9, 10, 11 fed with A.C. from source 116. Capacities 113 are connected respectively to opposing primary coils 14, 15 of transformer 16. The second arm 9 comprises a balancing capacity 17 and the third and fourth arms 10, 11 are connected to coils 18, 19 of a voltage regulation transformer having a third coil 20..The effect of capacity changes in arm 8 is balanced against fixed capacity 17 resulting in a signal in coil 20 which is treated in the same manner as the output from 115, Fig. 11.