Apparatus and appertaining method for upfinding in spinning projectiles using a phase-lock-loop or correlator mechanism
AssigneeHoneywell International Inc.
InventorsErik Lindquist, Ruth D. Kreichauf
Life of this patent
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Abstract
The invention relates to the field of gun-launched guidance systems and to a navigation system based on inertial sensors mounted in a spinning projectile using at least one rotation sensing device with input components perpendicular to the spinning body's longitudinal axis, and an appertaining method for upfinding. The phase of the sinusoidal angular rate as detected by a phase-locked loop or correlator is used to determine the local vertical orientation. This invention may be used to align the inertial navigation system in spinning projectiles in ballistic trajectories, which can include artillery shells, satellites or underwater torpedoes.
Claims19
An apparatus for estimating a rotation angle in a spinning projectile, comprising:
- an inertial sensor comprising a signal output that outputs a rotation signal related to a rate of rotation about the longitudinal axis;
- a phase detector comprising an input connected to the signal output of the inertial sensor, the phase detector further comprising an output at which a phase error between the rotation signal and a test signal, the test signal being derived by the phase detector, is provided, the phase detector being configured to reduce the phase error to zero via a feedback path;
- and
- an output connected to the output of the phase detector at which an estimated rotation angle is provided.
A method for estimating a roll angle in a spinning projectile, comprising:
- providing an inertial sensor on the projectile;
- launching the projectile in a ballistic trajectory, causing the projectile to spin about a longitudinal axis of the projectile;
- producing a rotation signal by the inertial sensor in response to the spin;
- inputting the rotation signal to a phase detector;
- producing a phase error between the rotation signal and a test signal with the phase detector;
- reducing the phase error to zero by providing a phase correction via a feedback path for the phase error;
- and
- outputting an estimated roll angle to an external system output.
The method according to 12, wherein outputting the estimated roll angle to an external system output further comprises:
- outputting the estimated roll angle to a complementary filter;
- enhancing the estimated roll angle with the complementary filter to dampen at least one of precession or nutation effects and smoothen the estimated roll angle;
- and
- outputting the enhanced estimated roll angle to the external system output.
Dependencies are inferred from the claim text.