"An inertial navigation system (INS) is a navigation aid that uses a computer, motion sensors (accelerometers), rotation sensors (gyroscopes), and occasionally magnetic sensors (magnetometers) to continuously calculate by dead reckoning the position, the orientation, and the velocity (direction and speed of movement) of a moving object without the need for external references.[1] It is used on vehicles such as ships, aircraft, submarines, guided missiles, and spacecraft."

https://en.wikipedia.org/wiki/Inertial_navigation_system