Natalie

Note: This material is for reference purposes only

Operation
Inertial Navigation System does not have frequency.
Inertial Navigation System (INS) provides the pilot with precision navigation data referenced to Latitude and Longitude. Accelerometers and gyros calculated the linear degrees of freedom, velocity, measured the movement in the three rotational degrees of freedom to form the Inertial Navigation System. There are three linear degrees of freedom of x, y, z to specify position. There are three angular degrees of freedom of pitch, yaw, and roll to measure the attitude.

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Pitch (Nose up and down), yaw (Nose left and right) and roll (Clockwise or counter-clockwise from the cockpit.


axis.gif
Math background of A six degree of freedom where x, y, z implies the linear of freedom and three rotary components.



inertialplatform.gif
There are the gyros which would be mounted on the aircraft for the INS measurement in the three rotational and three linear degrees of freedom.


In 1967, M. Schuler had an idea about if the center of suspension is placed at res at the center of a circle, and the center of oscillation is placed in and restrained to its circumference, then the pendulum is normal to the locally vertical true. In applying this concept to the three-dimensional case of the earth, he did apply his idea with gyrocompass steaming error oscillations. Schuler’s idea and the concept of inertial navigation were the same with respect to the two artificial horizons involved. Inertial navigation systems are used in civil and military aviation, submarines and space technology in the past because it is so expensive to install one in the small aircraft.
It is not necessary to put any location or information equipment, so it is a self-contained or autonomous system. The gyroscopes that mounted in the INS are so expensive and the parts would be affected by the friction so the drift happens. Once the alignment gets disturb, it has to be repeated.
Aircraft Equipments
Inertial Reference Unit
èAccelerometer
èRing Laser or Fibre Optic Gyro
èFlight Management Computer
Ground Equipment
èUsing local vertical and direction of true north
èCompass and sensors
èComputer database
èInertial Measurement Unit
Inputs
Information
èGravity
èEarth’s Rotation
èEarth’s Geometry
Pilot inputs
èPresent position of the aircraft
èHorizontal alignment and heading based on assumptions
Output
Information for the pilot
èLatitude
èLongitude
èTrue heading
èDistance to waypoint
èGround speed
èWind speed
èWind direction
Testing
No Frequency for INS testing
Parameters Testing
èPosition
èVelocity
èAttitude
èSix-degree of freedoms
èAtmospheric effects
èRF interference
èFlight dynamics
èBias instability
Equipment
èInertial Reference Unit
èComputer database
èGPS
èDME
Step by step how to test INS
èUsing local vertical and sensing earth’s rotation allows aircraft to estimate latitude and computer direction of true north.
èPresent position is then entered and aircraft is ready to navigate
èBecause aircraft is referenced to true north, it can establish magnetic heading from a computer database.
èRemote reading compass system is not required
èWith aid of FMC and navigation database IRU becomes INS

References

http://pilotjocky.blogspot.com/2008/09/inertial-navigation-system-ins.html

Instructor Notes

http://www.electronic-engineering.ch/study/ins/ins.html

http://fourier.eng.hmc.edu/e80/inertialnavigation/node4.html