Guidance, navigation and control
Guidance, navigation and control
Guidance, navigation and control (abbreviated GNC, GN&C, or G&C) 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.[1][2][3]
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 whilst maintaining vehicle stability.
GNC systems
GNC systems are found in essentially all autonomous or semi-autonomous systems. These include:
Autopilots
Driverless cars, like Mars rovers or those participating in the DARPA Grand Challenge
Guided missiles
Precision-guided airdrop systems
Reaction control systems for spacecraft
Spacecraft launch vehicles
Unmanned aerial vehicles
Auto-steering tractors
See also
Guidance system
Navigation
Control engineering
Aeronautics
Missile guidance
Navigation system
Air navigation
Aircraft flight control system
Flight control surfaces