[Autopilot] Re: Fixed wing aircraft (Jake McGuire)

[Carstens N <car...@su...>]

Hi Jake.
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Hope this does not come as old news...
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Does this same problem also arise if you try to perform a coordinated
turn in a helicopter with the current system, as opposed to
"stop-yaw-start"?

Yes, i would say. But you seem to understand the basic problem, so i =
will not bore you with detail. But the long and short of it: =
accelerometers measurements can only be used uncorrected to calculate =
pitch and roll angles if there is no acceleration. The Rotomotion / =
source forge autopilot EKF assumes the accelerations are small and of =
short duration - well, in the old code. That is NOT the case during =
coordinated turns. Old story: direction is changing all the time, =
although you might be flying at a constant speed. What is worse is that =
it is very difficult to build a good IMU without GPS or / and good rate =
gyroscopes...=20
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So, the sensors being used to correct your estimates (accelerometers), =
might give you bigger problems!! You are lying to your EKF by using =
accelerometers to correct estimates during accelerated flight. If you =
can find "better measurements" of your pitch and roll angles, use them. =
Not the accelerometers...=20
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Sorry, talking too much.
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Cheers,
Nicol.