RADAR Based Collision Avoidance for Unmanned Aircraft Systems

Unmanned Aircraft Systems (UAS) have become increasingly prevalent and will represent an increasing percentage of all aviation. These unmanned aircraft are available in a wide range of sizes and capabilities and can be used for a multitude of civilian and military applications. However, as the number of UAS increases so does the risk of mid-air collisions involving unmanned aircraft. This dissertation aims present one possible solution for addressing the mid-air collision problem in addition to increasing the levels of autonomy of UAS beyond waypoint navigation to include preemptive sensor-based collision avoidance. The presented research goes beyond the current state of the art by demonstrating the feasibility and providing an example of a scalable, self-contained, RADAR-based, collision avoidance system. The technology described herein can be made suitable for use on a miniature (Maximum Takeoff Weight \u3c 10kg) UAS platform. This is of paramount importance as the miniature UAS field has the lowest barriers to entry (acquisition and operating costs) and consequently represents the most rapidly increasing class of UAS

The applications of satellites to communications, navigation and surveillance for aircraft operating over the contiguous United States. Volume 1 - Technical report

Satellite applications to aircraft communications, navigation, and surveillance over US including synthesized satellite network and aircraft equipment for air traffic contro

Wideband Wilkinson Power Divider For Uav Phased Array Radar

The purpose of this project is to design a wideband Wilkinson power divider as part of an active phased array radar system for use in Unmanned Aerial Vehicle (UAV) applications. In order to comply with the entire system, the power divider was restricted in size, operating frequency, and bandwidth. The proposed power divider was integrated into a 10 GHz phased array system for future development in a transmitting and receiving system. The Wilkinson power divider was designed to provide 2 GHz bandwidth centered at 10 GHz. In order to provide the bandwidth, a 4&ndashstage Wilkinson power divider was designed and fabricated. It was then tested thoroughly to provide Printed Circuit Board (PCB) characteristics for integration within the system. Port isolation, phase error, and PCB power losses were found for the power divider and recorded to provide better integration into the radar system. The experimental results compared well with the simulated models created in the design phase. The final modularly designed phased array radar consisted of a Vivaldi antenna array, phase shifter and amplifier module, and control module. The focus of the work presented is the Wilkinson power divider that was designed to meet stringent design requirements for space, operating frequency, and phase error. The result is a fabricated Wilkinson power divider that met all the requirements and the module functions within the phased array system

Navigation and guidance requirements for commercial VTOL operations

The NASA Langley Research Center (LaRC) has undertaken a research program to develop the navigation, guidance, control, and flight management technology base needed by Government and industry in establishing systems design concepts and operating procedures for VTOL short-haul transportation systems in the 1980s time period. The VALT (VTOL Automatic Landing Technology) Program encompasses the investigation of operating systems and piloting techniques associated with VTOL operations under all-weather conditions from downtown vertiports; the definition of terminal air traffic and airspace requirements; and the development of avionics including navigation, guidance, controls, and displays for automated takeoff, cruise, and landing operations. The program includes requirements analyses, design studies, systems development, ground simulation, and flight validation efforts

Coverage of Continuous Regions in Euclidean Space Using Homogeneous Resources with Application to the Allocation of the Phased Array Radar Systems

Air surveillance of United States territory is an essential Department of Defense function. In the event of an incoming aerial attack on North America, the DoD, Department of Homeland Security, and Federal Aviation Administration surveillance capabilities are critical to discovering and tracking the threat so that it can be eliminated. Many of the currently used surveillance radar will reach the end of their design life within ten to twenty years. By replacing the current radar network with a single integrated network of Multifunction Phased Array Radar (MPAR) units, surveillance capabilities can be enhanced and life cycle cost can be reduced. The problem of determining the location of required MPAR units to provide sufficient air surveillance of a given area is a large problem that could require a prohibitively long time to solve. By representing the area of surveillance as a polygon and the MPAR units as guards with a defined circle of detection, this problem as well as similar surveillance or coverage problems can be expressed with easily adjustable parameters. The problem of covering the interior and exterior of a polygon region with a minimal number of guards with homogeneous capabilities is not well researched. There are no methods for determining the minimal number of guards required to cover the interior and exterior of a polygon at a desired coverage level less than 100 percent. This paper describes an iterative method for determining a small number and location of guards required to cover a convex polygon both fully and at a specified percentage coverage less than 100 percent. Results are presented to show that the developed methodology produces a smaller number of required MPAR units using less time than a comparable method presented in the literature. A goodness measure of the method is presented with respect to a lower bound for over 1000 test cases. Results for the United States Northern Command MPAR instance of this problem are presented to provide full and partial coverage of the Continental United States and 25 key cities of interest. The methodology developed in this thesis can be used to provide minimal cost surveillance recommendations over key areas or events, placement of communications resources, or other limited range resource

Safety‐oriented discrete event model for airport A‐SMGCS reliability assessment

A detailed analysis of State of the Art Technologies and Procedures into Airport Advanced-Surface Movement Guidance and Control Systems has been provided in this thesis, together with the review ofStatistical Monte Carlo Analysis, Reliability Assessment and Petri Nets theories. This practical and theoretical background has lead the author to the conclusion that there is a lack of linkage in between these fields. At the same of time the rapid increasing of Air Traffic all over the world, has brought in evidence the urgent need of practical instruments able to identify and quantify the risks connected with Aircraft operations on the ground, since the Airport has shown to be the actual ‘bottle neck’ of the entire Air Transport System. Therefore, the only winning approach to such a critical matter has to be multi-disciplinary, sewing together apparently different subjects, coming from the most disparate areas of interest and trying to fulfil the gap. The result of this thesis work has come to a start towards the end, when a Timed Coloured Petri Net (TCPN) model of a ‘sample’ Airport A-SMGCS has been developed, that is capable of taking into account different orders of questions arisen during these recent years and tries to give them some good answers. The A-SMGCS Airport model is, in the end, a parametric tool relying on Discrete Event System theory, able to perform a Reliability Analysis of the system itself, that: • uses a Monte Carlo Analysis applied to a Timed Coloured Petri Net, whose purpose is to evaluate the Safety Level of Surface Movements along an Airport • lets the user to analyse the impact of Procedures and Reliability Indexes of Systems such as Surface Movement Radars, Automatic Dependent Surveillance-Broadcast, Airport Lighting Systems, Microwave Sensors, and so on… onto the Safety Level of Airport Aircraft Transport System • not only is a valid instrument in the Design Phase, but it is useful also into the Certifying Activities an in monitoring the Safety Level of the above mentioned System with respect to changes to Technologies and different Procedures.This TCPN model has been verified against qualitative engineering expectations by using simulation experiments and occupancy time schedules generated a priori. Simulation times are good, and since the model has been written into Simulink/Stateflow programming language, it can be compiled to run real-time in C language (Real-time workshop and Stateflow Coder), thus relying on portable code, able to run virtually on any platform, giving even better performances in terms of execution time. One of the most interesting applications of this work is the estimate, for an Airport, of the kind of A-SMGCS level of implementation needed (Technical/Economical convenience evaluation). As a matter of fact, starting from the Traffic Volume and choosing the kind of Ground Equipment to be installed, one can make predictions about the Safety Level of the System: if the value is compliant with the TLS required by ICAO, the A-SMGCS level of Implementation is sufficiently adequate. Nevertheless, even if the Level of Safety has been satisfied, some delays due to reduced or simplified performances (even if Safety is compliant) of some of the equipment (e.g. with reference to False Alarm Rates) can lead to previously unexpected economical consequences, thus requiring more accurate systems to be installed, in order to meet also Airport economical constraints. Work in progress includes the analysis of the effect of weather conditions and re-sequencing of a given schedule. The effect of re-sequencing a given schedule is not yet enough realistic since the model does not apply inter arrival and departure separations. However, the model might show some effect on different sequences based on runway occupancy times. A further developed model containing wake turbulence separation conditions would be more sensitive for this case. Hence, further work will be directed towards: • The development of On-Line Re-Scheduling based on the available actual runway/taxiway configuration and weather conditions. • The Engineering Safety Assessment of some small Italian Airport A-SMGCSs (Model validation with real data). • The application of Stochastic Differential Equations systems in order to evaluate the collision risk on the ground inside the Place alone on the Petri Net, in the event of a Short Term Conflict Alert (STCA), by adopting Reich Collision Risk Model. • Optimal Air Traffic Control Algorithms Synthesis (Adaptive look-ahead Optimization), by Dynamically Timed Coloured Petri Nets, together with the implementation of Error-Recovery Strategies and Diagnosis Functions

Interferometric modification of the Lockheed Martin PSTAR system to facilitate three dimensional airspace surveillance

Thesis (M.S.) University of Alaska Fairbanks, 2011The Lockheed Martin PSTAR is a monostatic radar system that provides range, azimuth, and radial velocity information of detected targets. While this system is useful for airspace surveillance in remote locations due to its portability and durability, it lacks the ability to record target information and the ability to estimate target elevation angle, resulting in a vertical arc of possible target locations. Due to a desire to use the PSTAR for applications that require logging three-dimensional target information, a spatial interferometric modification has been implemented. The PSTAR estimates range from pulse propagation delay and azimuth angle from the orientation of the antenna on a rotating pedestal. Two PSTAR antennas were removed from their housings and mounted, vertically separated, in a custom enclosure allowing for the estimation of elevation angle through spatial interferometry. The reflected signal is received by both antennas, mixed to baseband, and then the two pairs of I/Q channels are simultaneously sampled at 1 MS/s. Target elevation angle is estimated by determining the phase difference of the target's reflection received by the two vertically spaced antennas. Range, azimuth, and radial velocity are also estimated. All data collection was implemented in LabVIEW and data post-processing was implemented in MATLAB.1. Introduction -- 1.1. Unmanned aerial vehicles -- 1.2. FAA requirements -- 1.3. PFRR requirements -- 1.4. Thesis overview -- 2. Description of PSTAR -- 2.1. PSTAR hardware -- 2.2. PSTAR testing -- 2.3. Internal PSTAR communications -- 2.4. Beam pattern -- 3. Estimation of target parameters -- 3.1. Radar fundamentals -- 3.1.1. Power -- 3.1.1.1. Radar equation -- 3.1.1.2. Noise -- 3.1.1.3. Signal to noise ratio -- 3.1.2. Azimuth -- 3.1.3. Range -- 3.1.3.1. Range ambiguity -- 3.1.4. Doppler velocity -- 3.1.4.1. Doppler velocity ambiguity -- 3.2. 3D Target location -- 3.2.1. Triangulation -- 3.2.2. Interferometry -- 3.2.2.1. Elevation ambiguity -- 4. Data collection -- 4.1. Azimuth data -- 4.1.1. Digital data from pedestal -- 4.1.2. Resolver -- 4.1.3. Hall effect sensor -- 4.2. I/Q data -- 4.2.1. Analog to digital converter -- 4.2.2. Dual antenna -- 4.2.3. PXI system -- 4.3. Modified PSTAR system -- 4.4. Data collection program -- 4.4.1. North alignment -- 4.4.2. I/Q data -- 4.4.2.1. Calibration data -- 4.4.2.2. Operational data -- 5. Data processing -- 5.1. Overview -- 5.2. Calibration -- 5.3. Signal conditioning -- 5.3.1. Data packaging -- 5.3.2. Removal of voltage discontinuities -- 5.4. Target detection -- 5.4.1. Azimuth -- 5.4.2. Range -- 5.4.2.1. Matched filter -- 5.4.2.2. Moving target indicator -- 5.4.2.3. Oversampled point target detection filter -- 5.4.3. Doppler velocity -- 5.4.4. Elevation angle -- 5.5. Processing demand -- 6. Testing and verification -- 6.1. Simulated data -- 6.2. Cooperative target tests -- 7. Conclusions and future improvements -- 7.1. Unused algorithms -- 7.1.1. Detailed calibration -- 7.1.2. Cluttermap -- 7.2. North alignment -- 7.3. FPGA based data collection -- 7.4. Replace PSTAR components -- Bibliography -- Appendix

General aviation weather avoidance sensor study

General aviation weather avoidance sensor stud

Vision based strategies for implementing Sense and Avoid capabilities onboard Unmanned Aerial Systems

Current research activities are worked out to develop fully autonomous unmanned platform systems, provided with Sense and Avoid technologies in order to achieve the access to the National Airspace System (NAS), flying with manned airplanes. The TECVOl project is set in this framework, aiming at developing an autonomous prototypal Unmanned Aerial Vehicle which performs Detect Sense and Avoid functionalities, by means of an integrated sensors package, composed by a pulsed radar and four electro-optical cameras, two visible and two Infra-Red. This project is carried out by the Italian Aerospace Research Center in collaboration with the Department of Aerospace Engineering of the University of Naples “Federico II”, which has been involved in the developing of the Obstacle Detection and IDentification system. Thus, this thesis concerns the image processing technique customized for the Sense and Avoid applications in the TECVOL project, where the EO system has an auxiliary role to radar, which is the main sensor. In particular, the panchromatic camera performs the aiding function of object detection, in order to increase accuracy and data rate performance of radar system. Therefore, the thesis describes the implemented steps to evaluate the most suitable panchromatic camera image processing technique for our applications, the test strategies adopted to study its performance and the analysis conducted to optimize it in terms of false alarms, missed detections and detection range. Finally, results from the tests will be explained, and they will demonstrate that the Electro-Optical sensor is beneficial to the overall Detect Sense and Avoid system; in fact it is able to improve upon it, in terms of object detection and tracking performance