Guidance, Navigation and Control
Encyclopedia
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 a rocket's dynamics, human reaction time is too slow to control this movement. Therefore, systems—now almost exclusively based around digital electronics—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. In general,
Examples for GNC systems include:
Engineering
Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...
dealing with the design of systems to control the movement of vehicles, especially, automobiles
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
, ships
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...
, aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
, and spacecraft
Spacecraft
A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....
. In many cases these functions can be performed by trained humans. However, because of the speed of a rocket's dynamics, human reaction time is too slow to control this movement. Therefore, systems—now almost exclusively based around digital electronics—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
Autonomous robot
Autonomous robots are robots that can perform desired tasks in unstructured environments without continuous human guidance. Many kinds of robots have some degree of autonomy. Different robots can be autonomous in different ways...
or remote
Telerobotics
Telerobotics is the area of robotics concerned with the control of robots from a distance, chiefly using wireless connections , "tethered" connections, or the Internet...
control. In general,
- Navigation refers to the determination, at a given time, of the vehicle's location and velocity (the "state vectorState vector*A state vector in general control systems describes the observed states of an object in state space, e.g. in variables of the degrees of freedom for motion *A state vector in general control systems describes the observed states of an object in state space, e.g. in variables of the degrees of...
") as well as its attitudeAttitude-Science and engineering:* Attitude as orientation of a geometric figure, such as a line, plane or rigid body* Attitude as strike or dip of a layer of rock in geology* Attitude of a wing or aircraft relative to airflow...
, - Guidance refers to the determination of the desired path of travel (the "trajectoryTrajectoryA trajectory is the path that a moving object follows through space as a function of time. The object might be a projectile or a satellite, for example. It thus includes the meaning of orbit—the path of a planet, an asteroid or a comet as it travels around a central mass...
") from the vehicle's current location to a designated targetTargetingTargeting is to make a thing or group of things a target, to select it or them to be acted upon.* Targeting , to select objects or installations to be attacked, taken, or destroyed...
, as well as desired changes in velocity, rotation and acceleration for following that path, and - Control refers to the manipulation of the forces, by way of steering controls, thrusters, etc., needed to track guidance commands while maintaining vehicle stabilityDirectional stabilityDirectional stability is stability of a moving body or vehicle about an axis which is perpendicular to its direction of motion. Stability of a vehicle concerns itself with the tendency of a vehicle to return to its original direction in relation to the oncoming medium when disturbed away from...
.
Examples for GNC systems include:
- AutopilotAutopilotAn autopilot is a mechanical, electrical, or hydraulic system used to guide a vehicle without assistance from a human being. An autopilot can refer specifically to aircraft, self-steering gear for boats, or auto guidance of space craft and missiles...
s - Driverless carDriverless carAn autonomous car, also known as robotic or informally as driverless, is an autonomous vehicle capable of fulfilling the human transportation capabilities of a traditional car. As an autonomous vehicle, it is capable of sensing its environment and navigating on its own...
s, like Mars roverMars RoverA Mars rover is an automated motor vehicle which propels itself across the surface of the planet Mars after landing.Rovers have several advantages over stationary landers: they examine more territory, they can be directed to interesting features, they can place themselves in sunny positions to...
s or those participating in the DARPA Grand ChallengeDARPA Grand ChallengeThe DARPA Grand Challenge is a prize competition for driverless vehicles, funded by the Defense Advanced Research Projects Agency, the most prominent research organization of the United States Department of Defense... - Guided missileGuided MissileGuided Missile is a London based independent record label set up by Paul Kearney in 1994.Guided Missile has always focused on 'the underground', preferring to put out a steady flow of releases and developing the numerous GM events around London and beyond....
s - precision-guided airdropAirdropAn airdrop is a type of airlift, developed during World War II to resupply otherwise inaccessible troops, who themselves may have been airborne forces. In some cases, it is used to refer to the airborne assault itself. Early airdrops were conducted by dropping or pushing padded bundles from...
systems - SpacecraftSpacecraftA spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....
launch vehicleLaunch vehicleIn spaceflight, a launch vehicle or carrier rocket is a rocket used to carry a payload from the Earth's surface into outer space. A launch system includes the launch vehicle, the launch pad and other infrastructure....
s