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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Robust Estimation And Adaptive Guidance For Multiple Uavs' Cooperation

Allen, Randal 01 January 2009 (has links)
In this paper, an innovative cooperative navigation method is proposed for multiple Unmanned Air Vehicles (UAVs) based on online target position measurements. These noisy position measurement signals are used to estimate the target's velocity for non-maneuvering targets or the target's velocity and acceleration for maneuvering targets. The estimator's tracking capability is physically constrained due to the target's kinematic limitations and therefore is potentially improvable by designing a higher performance estimator. An H-infinity filter is implemented to increase the robustness of the estimation accuracy. The performance of the robust estimator is compared to a Kalman filter and the results illustrate more precise estimation of the target's motion in compensating for surrounding noises and disturbances. Furthermore, an adaptive guidance algorithm, based on the seeker's field-of-view and linear region, is used to deliver the pursuer to the maneuvering target. The initial guidance algorithm utilizes the velocity pursuit guidance law because of its insensitivity to target motion; while the terminal guidance algorithm leverages the acceleration estimates (from the H-infinity filter) to augment the proportional navigation guidance law for increased accuracy in engaging maneuvering targets. The main objective of this work is to develop a robust estimator/tracker and an adaptive guidance algorithm which are directly applicable UAVs.
2

Modeling Of A Generic Laser Guided Weapon With Velocity Pursuit Guidance And Its Performance Analysis Using Various Control Strategies

Guner, Dunya Rauf Levent 01 August 2004 (has links) (PDF)
In this thesis, a base for the modeling and analysis of laser guided weapons is constituted. In particular, the effects of several control schemes on the performance of a generic laser guided weapon system are investigated. In this generic model, it is assumed that the velocity pursuit guidance is employed via a velocity aligning seeker as the sole sensor. The laser seeker is modeled experimentally, based on data obtained by conducting a series of tests. The laser reflection is also modeled. Aerodynamic coefficients of the generic geometry are generated by the software Missile Datcom. A nonlinear, six degree of freedom simulation is constructed incorporating 10 Hz laser sensing, velocity pursuit guidance, seeker model, and multiple control schemes. The effects of bang-bang, bang-trail-bang, multiposition and continuous control techniques on weapon performance are investigated for stationary and moving targets under ideal and noisy conditions. Flight characteristics like miss distance, range envelope, impact speed, and time of flight are monitored. Weapon&amp / #8217 / s maneuverability is investigated and the effect of employing a theoretical down sensor on the performance is demonstrated. In the light of simulation results, comparisons between various schemes are carried out, improvements on them and their flight envelopes are emphasized. It is concluded that the multiposition scheme provides a significant performance increase in most delivery types and can be an alternative to the continuous scheme. It is shown that the continuous scheme can achieve longer ranges only if backed up by a down sensor.

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