AS 11 - Inertial Navigation Flashcards
Review Questions
If unable to tune the HF radio, what are the troubleshooting procedures?
Change the volume setting, put it back to mid range and try again
Recycle power
Have another station take control of HF, then take control back
Have pilots take control of the HF, then take it back after 1-2 mins
Define Inertial Navigation System
A navigation aid that uses computer and motion sensors (accelerometers) to continuously calculate via dead reckoning the position, orientation and velocity of a moving object without the need for external references.
What are the advantages of INS?
Self contained Does not radiate Unjammable All weather operation World wide operation Relatively accurate position, very accurate attitude information
What are the generic INS components?
Accelerometers
Computers
Stable platform
Control and display unit
Explain the Law of Inertia
A body at rest tends to stay at rest, a body in motion remains in uniform motion with constant speed in a straight line unless acted on by an unbalanced external force.
Describe Newton’s 2nd law
Law of Motion
Acceleration produced by a particular force acting on a body is directly proportional to the magnitude of the force, and inversely proportional to the mass of the body.
Using measured acceleration: Integrate acceleration as a function of _____ to get _______.
Time & velocity
Using measured acceleration: Integrate velocity as a function of _____ to get _______.
Time & Displacement
True of false
Displacement equates to distance travelled.
True
How can we determine where we are now?
If we know where we started from and if we can measure acceleration in three dimensions.
Where we are = __________ + __________
Where we started + how far and in which direction we went
Y Axis or N/S = ____
X Axis or E/W = _____
Z Axis or U/D = _____
Roll
Pitch
Yaw
How does a Ring Laser Gyro work?
Lasers are fired simultaneously and travels in opposite directions around a cavity
The phase relationship between the two beams when they arrive at the detector determines motion of the AC.
If the RLG is stationary, how do the beams behave?
They complete the trip around the block at the same time since the optical path is the same.
The phase’s of both beam are the same when they arrive at the detector.
If an angular or azimuthal displacement (rotation) exists, the path length within a RLG will be?
Unequal
If a phase difference is measured within a RLG, what is implied?
A time difference between both beams arriving at the same point.
Explain the Differential Path Length Error. How is it eliminated?
If there exists a temperature difference between CERVIT cavities by even a fraction of a degree, there will be a time/ phase difference.
Eliminated by using one CERVIT cavity for both lasers
Explain the RLG Lock In error.
Non perfect optics within the cavity and mirrors will cause a certain amount of backscattering.
Backscattering tends to reinforce the beam in the traveling in the opposite direction.