Patent GB-337828-A (GB)
Title: Improvements relating to gyroscopically stabilised platforms
IPC: G01C21/18
Filed: 1929-08-09
Abstract: 337,828. Sperry Gyroscope Co., Ltd., and Rawlings, A. L. Aug. 9, 1929. Gyroscopic apparatus.-Apparatus for use on a ship for stabilizing a platform in azimuth and in elevation comprises a universally-mounted support constituting the platform to be stabilized and carrying an azimuth indicator and an indicator of the vertical, preferably consisting respectively of a gyro-compass and a freely mounted gyroscope with a vertical axis of rotation. The platform also carries two " slave " or relay gyroscopes which are coupled together so that they can process in opposite directions about their vertical axes, and means are provided to displace weights to alter the balance, of the support when the latter turns in azimuth relatively to the compass gyro, or when the slave gyros precess in opposite directions. Means are also provided for applying a torque about the vertical axis of the platform when the latter tilts relatively to the vertical gyro about one horizontal axis, and for applying torques to the slave gyros about their vertical axes when the platform tilts about its other horizontal axis. The platform 9 is mounted on a pedestal 1 by means of a gimbal ring 4 and a ball bearing 2 so as to be free to turn in azimuth and about horizontal axes 5-6 and 7-8. The compass gyro 11 is provided in the usual way with a follow-up element 15 having an extension carrying trolleys &c. 20 co-operating with contacts on a ring 19 which may be adjusted, e.g. as described in Specification 154,618, so as to be corrected for course and speed errors in order to render the azimuth of the platform independent of these errors. The vertical gyro 25 is supported in neutral equilibrium about an axis 28 in a gimbal ring 26 mounted on a horizontal axis 27 in supports fixed to the platform. To maintain the axis of the gyro 25 vertical, reversible motors 37, 38 are adapted to exert torques about the axes 27, 28, the circuits of these motors being controlled by pendulums 29, 30, at right-angles to each other, carrying contacts 35, 35' co-operating with pairs of contacts 36, 36<1> fixed to the platform 9. The slave gyros 39, 40 are disposed symmetrically with respect to the N-S axis of the platform, Fig. 3, with their horizontal axes of spin equally and oppositely inclined to the said axis and with freedom about vertical axes 41, 42. These gyros are connected by links 44, 45 to opposite ends of a link 46 pivoted about a vertical axis 47, so that they can precess in opposite directions about the axes 41, 42 but can only turn in the same direction about these axes by turning the whole platform in azimuth. The directions of spin of the gyros 39, 40 are such that a torque exerted on the platform about its E-W axis causes them to precess in the same direction while a torque about the N-S axis causes them to precess in opposite directions. Relative movement between the trolley 20 and ring 19 is therefor.e caused to displace a mass 48 in the N-S direction by energizing one or other of the electromagnets 51, 52 so as to produce a torque about the E-W axis to move the. platform in azimuth until the contact between the trolley 20 and ring 19 is interrupted. The movement of the weight 48 may also be made, by means of a contact 54 or 55, to complete the circuit of a reversible motor 53 displacing a weight 57 which is thereby moved to such a position as to compensate for any permanent want of balance of the platform about its E-W axis. Want of balance about the N-S axis causes opposite precessions of the gyros 39, 40 and the consequent movement of the link 46 is caused, by means of a trolley 65 on the link and stationary contacts 66, 67, to displace a weight 48<1> in the E-W direction. This weight may also control a motor 53<1> displacing a mass 57<1>. To annul tilting of the platform about its N-S axis a trolley 59 on the ring 26 co-operates with contacts 60 to control a motor 58 on the axis 47 of the link 46 so as to apply torques in opposite directions about the axes 41, 42 of the gyros 39, 40, the resulting precession about the N-S axis annulling the tilt. Similarly tilting about the E-W axis is caused to complete the circuit of a motor 62 arranged on the vertical axis of the platform and tending to turn the whole apparatus in azimuth. The resulting precession of the gyros 39, 40 about the E-W axis annuls the tilt. A modification is referred to, comprising only one relay gyroscope which has freedom only about its axis of spin relatively to the platform, this form being responsive to displacement of the platform about the vertical axis and about one particular horizontal axis. Specification 15679/11 is referred to.