Guidance, navigation and control (abbreviated GNC, GN&C, or G&C and within the context of NASA operations, often pronounced 'Gintsee' or (IPA) ʤɪnsiː) is a branch of engineering dealing with the design of systems to control the movement of vehicles, especially, automobiles, ships, aircraft, and spacecraft. In many cases these functions can be performed by trained humans. However, because of the speed of, for example, a rocket's dynamics, human reaction time is too slow to control this movement. Therefore, systems—now almost exclusively digital electronic—are used for such control. Even in cases where humans can perform these functions, it is often the case that GNC systems provide benefits such as alleviating operator work load, smoothing turbulence, fuel savings, etc. In addition, sophisticated applications of GNC enable automatic or remote control.
Guidance refers to the determination of the desired path of travel (the "trajectory") from the vehicle's current location to a designated target, as well as desired changes in velocity, rotation and acceleration for following that path.
Navigation refers to the determination, at a given time, of the vehicle's location and velocity (the "state vector") as well as its attitude.
Control refers to the manipulation of the forces, by way of steering controls, thrusters, etc., needed to execute guidance commands while maintaining vehicle stability.
GNC systems are found in essentially all autonomous or semi-autonomous systems. These include:
^Grewal, Mohinder S.; Weill, Lawrence R.; Andrews, Angus P. (2007). Global Positioning Systems, Inertial Navigation, and Integration (2nd ed.). Hoboken, New Jersey, USA: Wiley-Interscience, John Wiley & Sons, Inc. p. 21. ISBN 978-0-470-04190-1.
^Farrell, Jay A. (2008). Aided Navigation: GPS with High Rate Sensors. USA: The McGraw-Hill Companies. pp. 5 et seq. ISBN 978-0-07-164266-8.
Draper, C. S.; Wrigley, W.; Hoag, G.; Battin, R. H.; Miller, E.; Koso, A.; Hopkins, A. L.; Vander Velde, W. E. (June 1965). Apollo Guidance and Navigation (PDF) (Report). Massachusetts: Massachusetts Institute of Technology, Instrumentation Laboratory. pp. I-3 et seqq. Retrieved October 12, 2014.
AIAA GNC Conference (annual)
Academic Earth: Aircraft Systems Engineering: Lecture 16 GNC. Phil Hattis - MIT
Georgia Tech: GNC: Theory and Applications
NASA Shuttle Technology: GNC
Boeing: Defense, Space & Security: International Space Station: GNC
Princeton Satellite Systems: GNC of High-Altitude Airships. Joseph Mueller