Patent GB-804372-A (GB)
Title: Gyroscopic apparatus
Inventor: VACQUIER VICTOR
IPC: G01C19/38
Filed: 1955-06-17
Abstract: 804,372. Automatic control systems for gyroscopes. SPERRY RAND CORPORATION. June 17, 1955, No. 17510/55. Class 38 (4). [Also in Group XX] In a gyro-compass the axis of the rotor is maintained horizontal and North-South by a system in which tilt of the rotor bearing frame about a horizontal axis, as detected by a gravity-responsive device, controls means applying a torque about a horizontal axis to precess the rotor-bearing frame in azimuth, the torque being proportional to tilt for small angles of tilt and constant for larger tilts. As applied to a gyroscopic system producing electrical signals representative of movement of a craft about three mutually perpendicular axes gyros 18, 24, Figs. 1, are suspended with their spin axes horizontal and perpendicular to each other on wires carried by a frame 16 mounted on the craft in gimbal rings 12, 14 to permit movement about three perpendicular axes. The gyros are monitored by gravity-responsive conductive fluidtype level gauges 63, 171, mounted on the rotor cases, which produce electrical signals linearly proportional to tilt up to¢ degree for controlling through amplifiers (not shown) A.C. induction-type torque motors 72, 168 precessing the gyros. To maintain frame 16 fixed in azimuth an electromagnetic E-type pick-off 56 associated with gyro 18 controls, through an amplifier 58, a servomotor 60 rotating the frame. An electrical signal generator 62 driven by servomotor 60 then produces a signal indicative of craft heading. The spin axis of gyro 24 is maintained at right-angles to that of gyro 18 by an electromagnetic pick-off 163, associated with gyro 24, which controls through an amplifier (not shown) a torque motor 164 precessing gyro 24. To maintain frame 16 fixed relative to a horizontal plane, signals from pick-offs 30, 33 associated with gyros 18, 24, respectively, are applied to an electrical resolver unit 42, the rotor of which is coupled to frame 16 so that output signals, properly apportioned according to the heading of the craft, are applied through amplifiers 46, 47 to servomotors 36, 39 adjusting gimbal rings 12, 14. Electrical signal generators 52, 54 driven by motors 36, 39 respectively produce signals indicative of roll and pitch attitude. To obtain a suitably damped period of gyro 18 the signal from level gauge 63 controls through an amplifier (not shown) another torque motor .155 associated with gyro 18. Circuits involving computers of the dynamoelectric machine type are described, Figs. 2A, 2B (not shown), for applying the following corrections to gyro 18:-(a) Correction for the effect on level gauge 63 of northerly acceleration. An electrical signal, proportional to craft speed, derived from a pitot head is applied to a cosine resolver to produce a northerly speed signal which is differentiated and after modification to match the characteristic of the signal from level gauge 63 is applied to the amplifier controlling torque motor 72. (b) Correction for the effect of a constant torque, e.g. unbalance of the rotor case. The electrical signal from level gauge 63 corrected for northerly acceleration as at (a) above is integrated and applied as another signal controlling torque motor 72. The input to the integrator is automatically disconnected when the northerly acceleration exceeds a predetermined value, e.g. due to turning or change in speed. (c) Correction for movement of the craft relative to the earth. The northerly speed signal is added to a manually set northerly drift signal to obtain a signal representative of latitude from which is derived a signal representative of the tangent of latitude. A signal representative of easterly speed is derived from a sine-resolver supplied with the craft speed signal. Finally a signal representative of the product of easterly speed and tangent of latitude is produced and applied as a further signal controlling torque motor 72. (d) Correction for the vertical component of the Earth's rotation. An electrical signal proportional to the Earth's rotational speed is applied to a resolver multiplying by the sine of latitude, the resulting signal being applied as a still further signal controlling torque motor 72. (e) Correction of damping. The northerly acceleration signal and the northerly speed and drift signals are also applied to the control of torque motor 155. The corrections applied to gyro 24 are similar except that easterly speed and acceleration is measured instead of northerly speed and acceleration and the horizontal component of the Earth's rotation is measured instead of the vertical component. Specifications 545,284, [Group XX], 643,749 and 656,291 are referred to.