Inertial Navigation | Stable Platorm

Question 1

The platform is a gyro-stablised cluster of ___ accelerometers, in __ circular gimbals.

Answer 1

linear 3

Question 2

The 3 accelerometers consist of:

• Two ___ ones in the _ and _ axis, for ___ sensing.
• One in the _ axis

Answer 2

linear X Y LNAV

Z

Question 3

E and I bars may be used as they have ___ friction, otherwise some systems use pendulums

Answer 3

minimal

Question 4

The E and I bars may be used because they are highly ___, so a high flux density in proportion to the inducting field can be provided, with a rapid response to changes.

Answer 4

permeable

Question 5

The central arm is fed with ___ Hz _C, so the outer leg will pick up a secondary induced _C voltage, which is affected by the gap between the bars.

Answer 5

400 AC

Question 6

If there is no acceleration, the legs have the same ___, but with ___ polarity

Answer 6

voltage, opposite

Question 7

As the I bar moves away from the vertical, in the ___ direction __ the acceleration, the secondary induced voltage is amplified, phase detected and rectified to __, so that the torque can try to restore the accelerometer to the null position.

Answer 7

opposite to DC

Question 8

The amount of current involved is ___ proportional to the acceleration experienced

Answer 8

directly

Question 9

Phase detection ensures that the __ is of the right polarity to the I bar can be moved the right way

Answer 9

DC

Question 10

A stable platform keeps the ___ and ___ axes oriented N-S and E-W and the _ axis aligned with local gravity

Answer 10

X and Y, Z

Question 11

The stable platform ensures that the accelerometers do not mistake gravity for ___

Answer 11

acceleration

Question 12

There are _ rate integrating gyros that measure and use changes in aircraft vectors to orient the stable platform

Answer 12

3

Question 13

The output of the rate integrating gyros __creases as a function of their rate of displacement

Answer 13

in

Question 14

Rate integrating gyros provide a much ___er output response for a given input that displacement gyros do

Answer 14

high

Question 15

Rate integrating gyros are surrounded by ___ to eliminate friction and reduce bearing torques, and stop them precessing or toppling, rather than using a spring.

Answer 15

warm oil

Question 16

Rate integrating gyros are mounted inside __ cans

Answer 16

two

Question 17

The outer rate integrating gyro is ___ to the INS platform, and the inner one is ___ within it.

Answer 17

free to rotate

Question 18

When a tilt from the level position occurs, the gyro spin axes remain fixed in space, but their cases move, and an __ signal is measured to find the rate of movement

Answer 18

error

Question 19

The North rate integrating gyro senses the ___ and __ axis

Answer 19

North South

Question 20

The East rate integrating gyro senses the ___ and __ axis

Answer 20

East and West

Question 21

The Azimuth gyro senses the ___ axis

Answer 21

vertical

Question 22

The platform is forced to tilt, by ___ the gyros, in proportion to the Earth’s rate of turn, based on the latitude

Answer 22

torquing

Question 23

___ ___ is the main cause of error with an INS

Answer 23

Gyro drift

Question 24

Integrators convert the acceleration data into ___ and ___ information

Answer 24

velocity and distance

Question 25

The signals from the accelerometers go to the _st stage integrators which produce velocity information by multiplying the acceleration against time

Answer 25

1

Question 26

The _nd stage integrators multiply the resulting velocity against time to work out a distance

Answer 26

2

Question 27

For N/S, each minute is _nm, this is easily converted into change of latitude, which can be added to the start point to find the present latitude.

Answer 27

1

Question 28

The E/W distance has to be calculated with the aid of a ___ unit

Answer 28

secant