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I was wondering if someone could explain the alignment issues associated with a tri-axial accelerometer. It measures acceleration in terms of $g$. I have read some literature but I am unsure about the alignment issues involved.

Qmechanic
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branny12000
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  • Please, you that downvoted the question, explain why you did so. – stathisk Sep 01 '14 at 11:08
  • @Zet I'm not the downvoter but I'd guess it's that the question seems to not be about physics at all. – Jim Sep 01 '14 at 15:28
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    I voted to reopen. I know exactly what this question is asking, and it is about physics. Experimental physicists who don't pay attention to their instrumentation will get all kinds of whacked results, the most famous recent example being the FTL neutrinos. (Which of course weren't FTL at all; it was just a lousy connection.) – David Hammen Sep 01 '14 at 16:48
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    @DavidHammen Consider editting the question to make it clear. – Bernhard Sep 01 '14 at 20:09
  • @Bernhard - I don't know how to edit the question to make it clearer. It is already crystal clear to me, and most likely is to anyone who has had to deal with or model accelerometers on a spacecraft. Addressing accelerometer misalignment issues is one of the myriad of challenges confronted by spacecraft guidance, navigation, and control. – David Hammen Sep 01 '14 at 21:30
  • There are two main classes of misalignment problems. One is that the accelerometer's axes are supposed to be orthogonal to one another. That's never exactly the case. The other is that even if they were orthogonal, the orientation of the accelerometers with respect to the accelerometer housing, the orientation of the housing with respect to the IMU, and the orientation of the IMU with respect to the vehicle are never perfect. Blindly assuming orthogonality leads to one class of errors. Blinding assuming perfect alignment leads to another class of errors. – David Hammen Sep 01 '14 at 22:01
  • Key meta questions here include: http://meta.physics.stackexchange.com/q/4535/520 http://meta.physics.stackexchange.com/q/2948/ and perhaps http://meta.physics.stackexchange.com/q/5553/520 . The upshot is that the context matters. If Branny would like to say a few words about his (or her) need for this it might help resolve the issue. – dmckee --- ex-moderator kitten Sep 01 '14 at 23:12

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