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الأربعاء، 5 نوفمبر، 2014

Performance Enhancement of Unmanned Aerial Vehicles (UAVs) Guidance Technique

Title: Performance Enhancement of Unmanned Aerial Vehicles (UAVs) Guidance Technique
Author        : Moustafa Mohamed Ahmed
Collection   : M.Sc. Electric 
    Abstract:
 Unmanned aerial vehicles (UAVs) have become one of the most popular and promising means for both military and civilian posts and academic research areas. Localization of the UAVs and persistent tracking of a UAV have vital importance to provide a UAV with navigation information and help to cope with getting lost permanently. Indeed, inertial navigation system (INS) and global positioning system (GPS) seem to be adequate for navigation of UAVs. However, an alternative augmented navigation system for UAVs should be taken into consideration since INS has accumulated errors and GPS always has the possibility of jamming and satellite signal loss. Unmanned air systems (UASs) are playing increasingly prominent roles in defense programs and strategy around the world. For many of applications to develop into maturity, the reliability of UASs will need to increase, their capabilities will need to be extended further, their ease of use will need to be improved, and their cost will have to come down. The position estimation (location) problem of an object is a research subject that has attracted a lot of interest during the recent years. Several applications on location of expensive computer equipment, management of products and transportation are reported in the literature. Localization of UAVs is particularly interesting since they have important industrial applications. In addition, recent advances in electronics have dramatically improved the degree of integration of onboard control systems for UAVs. However, UAV localization is still an issue which requires to be improved. For outdoor applications, GPS provides low errors in location estimation but these errors are significant for UAVs. In addition GPS can only be used outdoor and far enough from buildings or large obstacles otherwise GPS signal become unreliable. Furthermore UAVs require an additional position estimation, to remain operating after GPS failure. GPS outage has been addressed by combining measurements from GPS and an inertial measurement unit (IMU). The inertial data are used as a reference trajectory, and GPS data are applied to update and estimate the state error of such a trajectory. The brain of the UAS is called the flight computer or autopilot. The autopilot, either solely or in combination with other avionics, uses onboard sensors to estimate its current position and orientation, perform flight control by translating flight commands into airframe actuator commands, and in some cases perform payload control such as, pointing a gimbaled camera.


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