Inertial guidance, method by which a vehicle is guided without contact with a ground base. Used primarily to guide missiles, airplanes, and submarines, inertial guidance provides navigation information through use of an inertial navigator. This device consists of a gyroscope, which indicates direction, and an accelerometer, which measures changes in speed and direction. Then a computer processes this information to calculate the vehicle's position and guide it. The inertial guidance system is based upon the ancient navigational technique by which speed and direction were used to calculate a vehicle's direction.
See also: Navigation.