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Session 10: UAV Operations and Flight Inspection Applications

Unmanned Aerial System for RFI Localization and GPS Denied Navigation
Adrien Perkins, Yu-Hsuan Chen, Sherman Lo and Per Enge, Stanford University
Location: Regency Ballroom
Date/Time: Thursday, Apr. 19, 8:30 a.m.

Radio frequency interference (RFI) has and continues to be a challenge faced by the aviation industry today. Short transient events, or longer duration interference, often caused by unintentional radiators in the vicinity of airports, all have the possibility to pose a risk to the industry, especially for systems such as GPS. In an effort to minimize the impact RFI sources, an unmanned aerial system (UAS) built on a multirotor platform, known as JAGER (Jammer Acquisition with GPS Exploration and Reconnaissance), is continuing to be developed as a means of autonomously and rapidly localizing GPS RFI.

Three main elements make up the system: sensing and measurement, path planning, and navigation. This paper discusses the continued improvements in the sensing and navigation elements of JAGER. For sensing, a three-element beam steering antenna has been developed to enable electronic rotation replacing the need for physically rotating the vehicle. For navigation, an infrared (IR) vision system has been developed to enable real time velocity measurements of the vehicle.

JAGER’s approach to the problem through using bearing information for localization of a single fixed jammer has been successfully demonstrated using a single directional antenna and the vehicle’s ability to rotate as the sensing system. In order to greatly increase the rate of bearing measurements and remove the need for a physical rotation, a three-element beam steering antenna has been developed, enabling the electronic rotation of the antenna allowing for a near 100x improvement in the observation rate (from about 30 seconds for a rotation to about 0.35 seconds for a rotation). With a near continuous observation of bearing, new techniques for source localization and navigation are enabled. Of great interest is the sensor’s ability to enable simultaneously localizing the source of the RFI and the position of the vehicle in a GPS denied environment. This paper describes the development of the beam steering antenna and the IR vision system that will enable the use of simultaneous localization and mapping techniques to solve the RFI localization and navigation problem. Both systems are tested in several real world environments with commercial GPS jamming equipment and results are discussed.

As the system is intended to localize the source of GPS interference, JAGER needs to be capable of navigating in a GPS denied environment. To augment the information from the RFI source, an infrared (IR) camera system is used to measure the velocity of the vehicle during flight. This paper discusses the use and performance of using optical flow techniques of IR imagery to obtain velocity measurements. Live day and night exercise results are presented and discussed.

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