Using Gyros and Accelerometers for Attitude detection

[andyg]

I know that gyros and accelerometers can measure tilt in a stationary application but how can you use them in planes where a cordinated turn would produce a false reading? I've searched everywhere but all I can find is a bunch of really complicated answers. Could someone please maybe define a system like this in Layman's terms? Thanks


Andy Goessling
andy@riddlehill.net

[Comatose]

A rate gyro will measure attitude accurately for a short period of time regardless of the forces on it, by integrating the signal. An accelerometer will measure attitude indefinitely by measuring gravity, but only when it isn't accelerating like it is during a turn.

To measure bank in a turn, for example, you could use the accelerometer to get an initial attitude, then during the turn switch to using the gyroscope, then once you exit the turn and are flat and level again, go back to the accelerometer.

A more involved method would be to have a reading for velocity. Knowing that and your turning rate, you can calculate the lateral acceleration. Subtract that from your accelerometer reading to get attitude.

Filtering is necessary to get rid of vibrations and wind buffeting, at least a low-pass filter on the accelerometer.

[TimAuton]

I know that gyros and accelerometers can measure tilt in a stationary application but how can you use them in planes where a cordinated turn would produce a false reading? I've searched everywhere but all I can find is a bunch of really complicated answers. Could someone please maybe define a system like this in Layman's terms?
If you turned it on during a turn you would get false readings. The accelerometers and gyros measure changes in attitude; the systen "knows" you are in a coordinated turn because you banked 15 degrees from wings-level and haven't banked back yet.