Simplified strapped down inertial navigation utilizing bang-bang gyro torquing
First Claim
1. A self contained strapped down inertial guidance system combining all axis, all attitude navigation comprising:
- a vehicle in which said inertial system is mounted,two wide angle, two-degree-of-freedom gyros having their cases rigidly mounted to said vehicle said gyros oriented so that their momentum vectors are non-parallel and having a predetermined span of angular freedom between said null and spin axes,means for torquing said gyros at constant rates in a bang-bang torque fashion so that the long term torquing rates of said gyros equal the rotational rate of said vehicle whereby all vehicle restrictions are removed, andmeans for computing corrections for said angular deviation between the null and spin axes by use of the electrical outputs of said gyro pickoffs.
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Abstract
A self-contained, strapped down guidance system combining all axes, all attitude navigation having two wide angle, two-degree-of-freedom gyros which provide attitude angle and angular rate signals along three axes. Accelerometer means provide signals representative of the acceleration along three orthogonally displaced independent axes. A first transformation matrix connected to the attitude angle output of the gyros and to the accelerometers transforms the gyro and accelerometer signals from body coordinates to gyro coordinates. A second transformation matrix connected to the output of the gyros, transforms the gyro coordinates into navigation coordinates. In order to perform navigational computations, computing means compute a transformation from gyro momentum vector (referenced to coordinate frame) to a navigational coordinate frame such as a locally vertical frame wherein the Z axis is always along the local vertical direction.
30 Citations
8 Claims
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1. A self contained strapped down inertial guidance system combining all axis, all attitude navigation comprising:
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a vehicle in which said inertial system is mounted, two wide angle, two-degree-of-freedom gyros having their cases rigidly mounted to said vehicle said gyros oriented so that their momentum vectors are non-parallel and having a predetermined span of angular freedom between said null and spin axes, means for torquing said gyros at constant rates in a bang-bang torque fashion so that the long term torquing rates of said gyros equal the rotational rate of said vehicle whereby all vehicle restrictions are removed, and means for computing corrections for said angular deviation between the null and spin axes by use of the electrical outputs of said gyro pickoffs. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A self-contained strapped down inertial navigation system for determining the attitude, position and velocity of a vehicle in which the navigation system is mounted comprising:
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two wide angle, two-degree-of-freedom gyros having their cases rigidly mounted to said vehicle for providing attitude angles and angular rate signals along three orthogonally displaced axes, accelerometer means for providing signals representative of the acceleration along said three linearly independent axes, a first transformation matrix connected to the output of said gyros and accelerometers for transforming said gyro and accelerometer signals from body coordinates to gyro coordinates, and a second transformation matrix connected to the output of said first matrix and said gyros for transforming said gyro coordinates into navigation coordinates.
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8. The method of determining the attitude, position, and velocity of a vehicle in a self-contained strapped down inertial navigation system comprising:
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torquing two wide angle, two degree of freedom gyros in such a manner so that only the long term torquing rates must equal those of said vehicle and so that all vehicle attitude restrictions are removed, maintaining a predetermined span of angular freedom between the null axes and the spin axes of said gyros, computing corrections for said angular deviation between said null axis and spin axis by use of the electrical output of the gyro pickoffs, computing the overall angular relationship between the body fixed frame and navigation frame by combining the said connection for angular deviation between said null axis and spin axes with said angular relationship between the gyro coordinate frame and navigation frame, measuring the vehicle acceleration by means of a linearly independent triad of accelerometers rigidly mounted to said vehicle, computing vehicle acceleration in navigation coordinates by transforming said vehicle acceleration into navigation coordinates by means of the matrix comprised of said vehicle attitude and augmenting it with local gravitational acceleration, and computing position and velocity by doubly integrating said acceleration in navigation coordinates subject to necessary coordination for rotation of the navigation frame.
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Specification