Inertial navigation system

An inertial navigation system estimates an object's orientation, velocity, and position by integrating measurements from accelerometers and gyroscopes. It operates without external navigation signals, but measurement errors accumulate over time.

Inertial measurement unit: A sensor assembly that measures specific force and angular velocity using accelerometers and gyroscopes. Its sensor measurements supply the raw motion data an inertial navigation system processes.
Accelerometer: A sensor that measures proper acceleration, including effects of motion and gravity. Its measurements provide the specific force that the system integrates to estimate motion.
Aircraft inertial navigation system: An aircraft navigation system that estimates attitude, velocity, and position from onboard inertial sensors. Aircraft use inertial estimates to maintain navigation when radio or satellite signals are unavailable.
Global Positioning System: A satellite-based radio navigation system that provides positioning and timing services worldwide. GPS can correct inertial drift, but its signals may be blocked, jammed, or spoofed.
Gyrocompass: A gyroscopic instrument that indicates true north by exploiting Earth's rotation. The gyrocompass established practical use of gyroscopic sensing for navigation before inertial systems.
Strapdown inertial navigation system: An inertial navigation architecture in which sensors remain fixed to the moving body and computation tracks its orientation. This common architecture replaces mechanically stabilized sensor platforms with continuous calculations.
Gyroscope: A sensor that measures angular velocity about one or more axes. Its measurements track orientation changes needed to resolve acceleration into navigation coordinates.
Submarine navigation: The methods submarines use to determine position and course while operating underwater. Water blocks ordinary satellite reception, making inertial navigation a key source of continuous position estimates.
Inertial navigation system and GPS integration: A navigation architecture that combines inertial measurements with GPS position and velocity estimates. Fusion uses GPS to limit drift while inertial sensors maintain continuity between satellite updates.
Hermann Anschütz-Kaempfe: A German engineer who developed the first practical gyrocompass in the early twentieth century. His gyrocompass work helped establish the stabilized gyroscopic instruments that preceded inertial navigation.

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