Document Type

Article

Publication Date

2008

Publication Title

Journal of Guidance, Control, and Dynamics

Abstract

"Modified linear theory provides reasonable impact predictions at high speeds. However, for typical small UAS mission speeds, less than 20-m/s impact errors were substantial due to large angles of attack and pitch rates. Low-speed linear theory was developed by including higher-order terms involving w and q that modified linear theory neglects. As a result, the angle of attack, pitch, and yaw predictions are significantly improved, leading to accurate impact predictions even at very low speeds. A predictive control scheme was developed to reduce dispersion using control surfaces near the tail. The predictive controller uses low-speed linear theory to rapidly predict the impact error using the current state and control. Based on the estimated impact error, the control is iteratively found to minimize the predicted-impact error. For an example munition, it was shown that the maximum number of iterations during the control solution only impacted the initial control estimates. Limiting the guidance algorithm to a single iteration had little impact on the final accuracy and permitted a rapid solution. It was shown for the example munition that the predictive guidance significantly reduced the CEP from 14.1 to 2.7 and 2.2 m when the maximum iterations were 1 and 10. Furthermore, for a typical high- explosive 40-mm grenade, the percentage of impacts within a lethal radius was increased from 10 to 78% when the maximum iterations were both 1 and 10. In practical applications, errors in the target location must beincluded when considering the probability of impact within a lethal range of a target."

Volume

31

Issue

2

First Page

768

Last Page

774

Comments

Originally published in the Journal of Guidance, Control, and Dynamics, Vol 31, No 3, pp 768-774, 2008.

http://arc.aiaa.org/loi/jgcd

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