Patent GB-545694-A (GB)
Title: Improvements in or relating to gyroscopes
IPC: G01C19/38
Filed: 1940-04-02
Abstract: 545,694. Automatic control systems for gyro. scopes. STEVENS, A. H. (Sperry Gyroscope Co., Inc.). April 2, 1940, No. 5878. [Classes 38 (ii) and 38 (iv)] [Also in Group XX] Alignment. - Deviation of the axis of a gyroscope frame alignment with a controlling body, e.g. a pendulum, is eliminated by applying a correcting torque controlled from deviation detecting means and causing precession towards the alignment desired, at least a part of the torque being under the control of an integrating device so as to be proportional to the time integral of the deviation. Any permanent torque disturbing the gyroscope is thus neutralized. Fig. 2 shows an air-borne gyroscope rotor 1 and a gimballed frame 5 carrying the driving stator G which is maintained in corresponding alignment with the axis of the rotor 1 by precession produced by two follow-up motors acting about two horizontal axes and controlled, e.g. by an inductive controller 13, such as is described in Specifications 360,428 and 417,995, [Group XXXVII]. A free pendulum 28 is journalled on an additional gimbal ring on an axis at 45 degrees to both the horizontal axes referred to. Any tilt of the gyro axis with reference to the true vertical is detected by the relative displacement between a round steel armature 29 on the pendulum and the four poles of a cruciform transformer 30 carried by the frame 5. This transformer has a control core with primary winding; secondary windings on each pair of opposite holes are connected in opposition in the respective input circuits of amplifiers 41, 42 so that the outputs are proportional respectively to the tilt components of the gyro-vertical in fore-and-aft and athwartship co-ordinates of the craft on which it is mounted. The outputs of these amplifiers are resolved into corresponding components in N-S and E-W coordinates so that they may be independent of ship's heading e.g. by means of a transformer 45 in which a resultant field, due to crossed coils 44, 46 fed from the respective amplifiers is adjusted by a compass repeater 71 with reference to coils 47, 48 fixed on axes set at 90 degrees to each other. The resulting currents, representing tilt components of the gyro in the two terrestial planes, are amplified and rectified to energize the fields of two integrating D.C. motors 53, 54, having constant solar energization and speeds proportional to field strength. Potentiometer sliders 59, 60 are thereby adjusted from their zero positions to produce an A.C. voltage which in sense and magnitude corresponds with the time integral of each tilt component. These are resolved again into corresponding components in the ship's co-ordinate system by a transformer 65, also adjusted by the compass repeater and each is combined with the related component from the amplifiers 42, 41 through transformers 90, 91. The resultant alternating currents are amplified, rectified and fed to fore and aft and athwartship coils 39, 391 and 38, 38<SP>1</SP> on an erector magnet 34 (Figs. 2 and 5). This magnet is carried by the frame 5 by which its centre pole 35 is maintained aligned with the axis of rotation of the gyro so that the energization of the outer poles will exert a lateral braking torque which will cause the gyro to precess in the plane of the tilt e.g. in the vertical direction required to maintain its axis aligned with the true vertical. To prevent overshorting and continual oscillation of the gyro axis the speeds of motors 53, 54 are so close that the rate of change of potentiometer potential is lower than the rate of change of gyro tilt. In operation the displacement of the potentiometer sliders persists and changes automatically with latitude to cause the magnet 34 always to exert such control as is required to give complete latitude correction. The slider 59 may carry a pointer registering with a scale to give latitude indications. Correction for ship's speed error is also obtained. A switch may be interposed at 82, 83 and operated by an acceleration indicator so that during longitudinal or centrifugal acceleration the tilt detector is ineffective; the movements of the transformer 65 cause the requisite rotation of the braking torque vector whilst the ship is turning. The invention may control the position of any gyroscope irrespective of the orientation of its axis. The Specification describes (Fig. 1, not shown) a system for maintaining horizontal the spin axis of a gyroscope wherein a follow-up ring surrounding the gyroscope is mounted on a vertical axis and maintained co-planar with a ring carrying the gimbals in which the gyroscope is mounted by electrical servomotor controlled in known manner. These parts are mounted in a pendulous casing providing gravitational control of the gyroscope. An inductive controller of the kind described in Specifications 360,428 and 417,995, the two parts of which are mounted respectively on the rotor case and the gimbal carrying ring furnishes an A.C. voltage which is a measurer of the tilt of the gyro casing. This voltage is rectified, amplified and applied to an integrating motor actuating a potentiometer which furnishes a D.C. voltage proportional to the time integral of the tilt and is compounded with the output from the amplifier proportional to the tilt to energize a solenoid co-operating with a magnet to produce a correcting precession torque. The solenoid and magnet are mounted respectively on the follow-up ring and the gimbal carrying ring. In a modified form of gyro-vertical (Fig. 4, not shown) a fixed button on the end of the gyro casing co-operates with the cores of the inductive tilt detector, and the erecting magnet acts upon a spherical surface on an extension of the rotor shaft or rotated independently e.g. a motor on the rotor casing. Other types of controller, e.g. electrolytic or pneumatic, may be used.