Control Authority of a Projectile Equipped With an Internal Unbalanced Part

[+] Author and Article Information
Geoffrey Frost, Mark Costello

Department of Mechanical Engineering, Oregon State University, Corvallis, OR 97331

J. Dyn. Sys., Meas., Control 128(4), 1005-1012 (Jan 08, 2006) (8 pages) doi:10.1115/1.2363205 History: Received September 11, 2004; Revised January 08, 2006

A key technical challenge for smart weapon developers is the design of appropriate control mechanisms that provide sufficient control authority to enable correction of typical trajectory errors while not excessively burdening the overall weapon design. The work reported here considers a rotating mass unbalance control mechanism, created by radial orientation of an internal part. To investigate the potential of this control mechanism, a seven degree-of-freedom flight dynamic model of a projectile, equipped with an internal part is defined. Using this dynamic model it is shown that by holding the internal part fixed with respect to a nonrolling reference frame, predictable trajectory changes are generated including predictable impact point changes. As expected, when unbalance-offset distance, or mass is increased, control authority increases proportionally. This control mechanism creates impact point changes that are the same order of magnitude as dispersion caused by errors induced at launch and in flight. Control authority is significantly altered with changing projectile characteristics, such as, the mass center location, pitch inertia, yaw inertia, aerodynamic drag, and aerodynamic normal force.

Copyright © 2006 by American Society of Mechanical Engineers
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Figure 1

Example system configuration

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Figure 2

Fin-stabilized system part roll angle time histories

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Figure 3

Fin-stabilized system control torque

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Figure 4

Control authority of fin stabilized projectile (launch angle=3deg)

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Figure 5

Fin-stabilized dispersion and average station line distance versus average velocity

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Figure 6

Control authority of spin stabilized projectile (launch angle=30deg)

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Figure 7

Control authority for nominal spin stabilized system (launch angle=15deg, 30deg, and 45deg)

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Figure 8

Part mass removal configuration

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Figure 9

Control authority versus part mass times part mass center offset

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Figure 10

Spin-stabilized dispersion versus time of part reformation




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