Please join us and be a part of the Avionics in the Midwest Lecture Series.
In this Lecture Series, we will explore the accomplishments of those who have made significant contributions to the field of Avionics. Each lecture will focus on a particular Guidance, Navigation, and Control technology, the history and impact of the technology, the professional and personal relationships of those involved in the development of the technology, and the theory behind the technology.
In the field of engineering, our current accomplishments are built on existing technologies and accomplishments of those who came before us. This Lecture Series explores significant technologies developed by engineers who came before us that we use and take for granted today. Further, this Lecture Series explores the technologies developed by engineering graduate students as they test and extend the limits of the current technologies.
The Twin Cities Section of the American Institute of Aeronautics and Astronautics (AIAA) and the North Star Section of the Institute of Navigation (ION) are proud to continue to host a Lecture Series that explores the history and impact of the technology and engineering behind avionics systems.
In this third part of the Lecture Series, the AIAA and ION are pleased to welcome Dr. Wouter Pelgrum of Ohio University and Mr. Hamid Mokhtarzadeh of the University of Minnesota. Dr. Pelgrum is a dynamic speaker with both academic and industrial experience who will share his experiences and thoughts on navigation in GNSS denied environments. Mr. Mokhtarzadeh is a Ph.D. candidate who will discuss the fusion of correlated random vectors which has applications in many real world navigation problems.
Avionics Lecture Schedule:
Date: Wednesday, 11 December 2013
6:00 – 6:30 pm Meet and Greet
6:30 – 7:00 pm Presentation: Mr. Hamid Mokhtarzadeh
7:00 – 8:30 pm Presentation: Dr. Wouter Pelgrum
Aerospace Engineering & Mechanics Hangar
University of Minnesota
110 Union Street SE
Minneapolis, MN 55455-0153
Dinner: Compliments of AIAA and ION
RSVP: Please email us at email@example.com if you plan to attend
Presenter: Dr. Wouter J. Pelgrum
Title: High-Performance Positioning, Navigation, and Timing When GPS is Not Available
Abstract: The American GPS system has made ultra-precise Positioning, Navigation, and Timing (PNT) virtually ubiquitous, affordable, and available worldwide to everyone. And satellite navigation is only getting better with the other existing and upcoming Global Navigation Satellite Systems (GNSS): GLONASS (Russia), Galileo (Europe), Beidou/Compass (China), QZSS (Japan), and IRNSS (India).
The unsurpassed performance of GNSS and its low user cost has fueled a wide range of applications, such as Personal Navigation Devices (PND) in cars, Automatic Identification System (AIS) for shipping, and Automatic Dependent Surveillance – Broadcast (ADS-B) for aviation. And not to forget GNSS time and frequency that is used for the synchronization of, for example, electrical power grids, communication systems, and financial networks.
With the growing number of GNSS-PNT applications there is also an increasing dependency: GNSS has become part of the world’s critical infrastructure, with significant safety, environmental, and economical impact associated with the unavailability or failure of GPS or other GNSS. The low received signal power, intrinsic to satellite systems, makes GNSS vulnerable to jamming and spoofing. Furthermore, solar events can cause significant ionosphere scintillation and thereby hinder acquisition and tracking of the L-band GNSS signals.
Over the past decade, there has been a significant and ongoing effort to improve the robustness of PNT: GNSS receiver and satellite technology have been improved, and GNSS has been integrated with a variety of sensors. Examples of multi-sensor integration are the combination of GNSS with inertial, barometric, vision, LIDAR, radar, and WIFI-based navigation solutions. All these new developments make you almost forget we navigated long before GPS was even conceived. Mariners navigated using celestial methods, and with systems such as Loran, Decca, and Omega.
Aviators used, and often still use, NDB, VOR, DME, and Loran.
This presentation focuses on the legacy radio navigation systems Loran-C (100 kHz) and DME/N (1 GHz), their working principles, performance, past and current usage, and their potential for future applications. Loran-C’s legacy position performance of 0.25 nmi and DME/N’s ranging performance of 0.2 nmi are no match for most of today’s stringent performance requirements, which necessitates system enhancements.
The maritime “Harbor Entrance and Approach” (HEA) procedure, for example, requires 8-20 m 95% positioning accuracy. A completely overhauled Loran-C system called “eLoran” makes this possible with modern solid-state transmitters, DSP receiver technology, novel receiver antenna design, and compensation of propagation-induced errors using differential corrections and ASF correction maps. HEA eLoran measurements in Tampa Bay Florida in 2004 demonstrated better-than 10 meter accuracy. Now, almost a decade later, Great Britain is rolling out eLoran services for all their major harbors. This is one of the examples of eLoran technology and applications that will be presented, together with land-mobile, maritime, and airborne measurement results.
The aviation community faces a challenge similar to that of the maritime community: GPS has enabled enhanced procedures at low cost, but how to protect against GPS outages? FAA’s Alternative Positioning, Navigation, and Time (APNT) program is tasked with that challenge. One of the candidate architectures is the Distance Measuring Equipment (DME) system. The legacy DME/N system is only specified to 0.2 nmi ranging performance, with DME/DME/IRU specified to the RNAV 1 level (approximately 1610m 95% positioning performance). The APNT target performance is RNP 0.3, or 370 m 95%, with integrity. Various techniques are under consideration to improve DME’s performance such as upgraded, state-of-the-art ground-station and avionics equipment. More revolutionary performance enhancements are obtained by novel techniques such as DME carrier phase, beat signal, and pulse modulation and TOA determination techniques. A brief overview of these techniques will be presented accompanied by flight test results and an outlook on the future of the system.
Biography: Dr. Wouter J. Pelgrum is an Assistant Professor of Electrical Engineering at Ohio University where he teaches electronic navigation-related courses. His research programs include GNSS, Inertial, DME, Loran, Time and Frequency transfer, integrated navigation systems, and advanced ground/flight test instrumentation systems. Prior to joining Ohio University in 2009, Wouter worked in private industry where he contributed to the development of an integrated GPS-eLoran receiver and antenna. From 2006 until 2008, Wouter operated his own company specializing in navigation-related research and consulting.
Presenter: Mr. Hamid Mokhtarzadeh
Title: Data Fusion when Correlation Matters
Abstract: The problem of fusing two or more uncertain quantities arises in aerospace applications. When the correlation between the quantities are zero (or known), the Kalman filter (or an alternative formulation) is an effective fusion algorithm. However, some amount of correlation is common, and if left unrestricted, this correlation could lead to filter divergence.
In this talk I describe scenarios where handling correlation is important. This is followed by the presentation of a fusion technique, known as covariance intersection, for handling unknown correlation. Finally, an automotive application simulation is used to demonstrate the performance of the filters.
Biography: Mr. Hamid Mokhtarzadeh is a Ph.D. candidate in the Department of Aerospace Engineering and Mechanics at the University of Minnesota. He earned a B.S. and M.S. in Aerospace Engineering and Mechanics from the University of Minnesota. His M.S. research focused on modeling and control of dynamical systems. Hamid’s current interests include data analysis and visualization, estimation, and integrated navigation systems.