MAE Seminar: Inertial Navigation Systems and Aiding

McDonnell Douglas Engineering Auditorium (MDEA)
Michael S. Braasch

Professor of Electrical Engineering, Ohio University

Abstract: Inertial navigation systems (INS) are modern technologically sophisticated implementations of the age-old concept of dead reckoning. The basic philosophy is to begin with a knowledge of initial position, keep track of speed and direction, and thus be able to determine position continually as time progresses. Perhaps surprisingly, the rise of GNSS has actually expanded the need for inertial-based systems. Accelerometers and gyroscopes are the basic sensors utilized and since INS are essentially self-contained, they do not suffer from interference or unavailability that can affect radio-based systems such as GNSS. Furthermore, INS are highly complementary to GNSS since they provide high data rates, low data latencies and attitude-determination along with position and velocity. This lecture will highlight the basic principles of operation and describe key error characteristics along with their impact.

For more than five decades, the Kalman filter has been the primary tool used to reduce inertial drift through the integration of various sensors. Specifically, aiding sources (e.g., stellar, Doppler, GPS, etc) are used by the filter to estimate the errors in the free inertial processing. Thus, the heart of any aided-inertial Kalman filter is the inertial error model including, specifically, sensor errors. We will discuss these models and explain how aiding source observations are then used by the filter, in conjunction with the models, to estimate the inertial errors. For example, a given aiding source may provide an independent measurement of position, yet somehow the filter is able to use this in order to estimate gyro biases in the inertial system.  Join us as we unravel these mysteries.

Bio: Michael Braasch holds the Thomas Professorship in the Ohio University School of Electrical Engineering and Computer Science, is a principal investigator with the Ohio University Avionics Engineering Center (AEC) and is a Distinguished Lecturer for IEEE AESS. He has been performing navigation system research for over 30 years and has served as a technical advisor both to the U.S. FAA and the International Civil Aviation Organization (ICAO). He has taught inertial navigation systems and aiding at all three U.S. manufacturers of navigation-grade inertial systems: Honeywell, Kearfott and Northrop Grumman. Braasch is also recognized as a leading authority in the characterization and mitigation of GNSS multipath and in the mid-1990s led the Ohio University research group that pioneered the GNSS software-defined receiver. He has extensive flight-testing experience with Ohio University’s fleet of research aircraft, has served as a visiting scientist at the Delft University of Technology in The Netherlands and has lectured for NATO AGARD in Russia, Turkey and Ukraine.  He has also given invited talks in Australia, Canada, China, France and New Zealand.  Braasch is a member of the GNSS-Inertial working group (WG-2C) of RTCA SC-159, serves on the Board of Governors of the IEEE AESS and is the founding chair of the AESS Navigation Systems Panel, as well as a Fellow of the Institute of Navigation and an instrument-rated commercial pilot.