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IRU - integrating accelerations?

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IRU - integrating accelerations?

Postby legoboyvdlp » Sun Nov 03, 2019 6:34 pm

Hi there,

Has anyone any experience with creating the IR part of an ADIRU unit. I've successfully created the ADR part (calculating computed airspeed, true air temperature, mach from the dynamic / static pressure as well as the static temperature output by the environment subsystem; angle of attack and barometric altitude come directly from the generic properties); next up is the IR part.

Details of the system:
- the A320 has a so-called "strap-down" laser gyro as well as accelerometers.
- the laser gyros provide inertial rotation data for each rotation axis; the accelerometers provide linear acceleration in each plane
- This is fed into a gimbal computer which takes roll, pitch, and yaw and the acceleration to output acceleration vectors for each plane
- From this, heading, attitude, position, velocity, acceleration, and rotation rates are calculated and sent to the other components.

Some thoughts:
- displacement is the integral of velocity which is the integral of acceleration, so we should be able to calculate position from an initial position. Is this correct?
- it appears that jsbsim already has a gyro component - along with a drift rate! Is this good enough to use - that is, feed in a drift value calculated elsewhere into?
- there is also an accelerometer component; but it does require knowing where the ADIRU are. I think they are in the avionics bay, but am not quite certain.

The part numbers are HG 1050 inertial reference system and HG1150 integrated air-data/inertial-reference system (ADIRS); I'll try and find more details.

I'm fairly sure the Shuttle has all this already, I'll be taking a look, but are there any other examples?
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