Inertial Navigation System
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Overview
The Inertial Navigation System (INS - not be be confused with Integrated Navigation System) is a "dead-reckoning device", a navigation system that (after initial latitude, longitude, heading and orientation conditions are set in the system) continuously computes the latitude and longitude of the ship by sensing acceleration. This is in contrast to other navigation systems (e.g. LORAN) which fix the ship's position by measuring position relative to some known object.
Basic components
The basic components of an inertial navigation system are:
- accelerometers
- gyroscopes
- servo systems
- computers
How it works
Accelerometers measure changes in speed or direction along the axis in which they lie. Their output is a voltage, or series of pulses (digital), proportional to whatever acceleration is experienced.
The accelerometers are mounted on a gyro-stabilized platform, which is maintained in the horizontal position regardless of the pitch, roll, or yaw of the ship. Ship’s heading changes cause the gyro signals to operate servo system motors, which in turn keep the platform stabilized. High-performance servo systems keep the platform stabilized to the desired accuracy.
Maintaining this accuracy over long periods of time requires that the system be updated periodically. This is done by resetting the system using information from some other navigation means; i.e., electronic, celestial, or dead-reckoning.
Advantages
The inertial navigations system has a major security advantage over other types of navigation systems because it is completely independent of celestial, visual and radio navigation aids. In addition, INS has the following advantages:
- It is self-contained
- It requires mimimal outside information
- It cannot be jammed
- It is unaffected by adverse weather conditions
- It does not radiate energy
- It is not detectable by enemy sensors
