Projectile navigation enhancement method
First Claim
1. A method of flight control of a projectile, the method comprising:
- providing the projectile with a microelectromechanical system (MEMS) inertial measurement unit (IMU); and
reducing trajectory errors by rolling the projectile while maintaining a roll reference in the MEMS IMU, thereby ameliorating the effect of inaccuracies in the MEMS IMU by canceling out at least some of the effect of inaccuracies of the MEMS IMU.
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Accused Products
Abstract
A projectile, such as a missile, rolls during at least a portion of its flight, while retaining its roll reference to enable navigation during the rolling period of flight. The roll reference may be retained by using a sensor, such as magnetometer, to periodically check and correct the roll reference. Alternatively or in addition the missile may alternate roll directions, for example varying roll rate in a substantially sinusoidal function. By rolling the missile inaccuracies in an inertial measurement unit (IMU) of the missile may be ameliorated by being to a large extent canceled out by the changes in orientation of the missile as the missile rolls. This enables use of IMUs with lower accuracy than would otherwise be required to obtain accurate flight. Thus accurate flight may be accomplished with less costly IMUs, without sacrificing the ability to navigate.
33 Citations
18 Claims
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1. A method of flight control of a projectile, the method comprising:
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providing the projectile with a microelectromechanical system (MEMS) inertial measurement unit (IMU); and reducing trajectory errors by rolling the projectile while maintaining a roll reference in the MEMS IMU, thereby ameliorating the effect of inaccuracies in the MEMS IMU by canceling out at least some of the effect of inaccuracies of the MEMS IMU. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of flight control of a projectile, the method comprising:
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during flight of the projectile, rolling the projectile periodically using a control system of the projectile, first rolling the projectile in a first direction, then rolling the projectile in a second direction that is opposite the first direction; wherein the rolling includes varying roll rate as a repeating periodic function over time, wherein the function alternates between the first direction and the second direction. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method of operating a projectile, the method comprising:
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providing the projectile with a microelectromechanical system (MEMS) inertial measurement unit (IMU) that maintains performance characteristics through accelerations associated with launching the projectile from a gun; and maneuvering the projectile during flight to reduce the effect of inaccuracies of the MEMS IMU, wherein the maneuvering ameliorates the effect of inaccuracies by canceling out at least some of the effect of inaccuracies. - View Dependent Claims (17, 18)
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Specification