GB1394663A - Stable platform system - Google Patents

Abstract

1394663 Gyroscopic apparatus U S A NAVY SECRETARY OF 18 Nov 1966 51873/66 Heading G1C A stable reference apparatus positioned with respect to the local vertical in an inertial navigation guidance system using correlated velocity guidance comprises a gyro-stabilized platform having positioned thereon a triad of accelerometers oriented to have their sensing axes each along a different axis of a three-axis mutually perpendicular co-ordinate system, one of the accelerometers having its input or sensitive axis in the direction of the average correlated velocity vector, and gimbaling means operatively attached to rotate the platform about the three axes of the coordinate system. In such an apparatus, the platform 11 is supported by shafts 12, 13 along its vertical axis and carries three single degree-offreedom accelerometers: the SR (slant-range) accelerometer 14, the SV (slant-vertical) accelerometer 15, and the J accelerometer 16. It also carries the inertial reference integrating gyros (IRIG's). Only one of the gyros, the J(IRIG) 17, is shown in Fig. 4. A middle gimbal 19 is supported on bearing surfaces where it intersects the shafts 12, 13, and it has shafts 21, 22 displaced 90 degrees from the shafts 12, 13 and passing through an outer gimbal 23 on bearing surfaces. The outer gimbal 23 is supported by shafts 24, 25 rotatably attached to a missile or vehicle body (not shown). In order to rotate the platform and gimbals about one another and to have indication of the angular difference between the platform, the middle gimbal and the outer gimbal, there are fastened to these components torque motors 27, 29 and 32, respectively, and resolvers 28, 31 and 33, respectively. In operation, the platform 11, in conjunction with the middle gimbal 19 and outer gimbal 23, operates to hold the accelerometers in their respective reference co-ordinates, regardless of the external movements of the vehicle to which it is fastened. As the platform is disturbed, the respective IRIG's generate signals to operate the respective torque motors to bring the platform back to its original orientation. The accelerometers, on the other hand, which indicate the vehicle's velocity at some fixed time after leaving a predetermined point, are used primarily in the navigation process.