joebarteam's blog archive for October, 2011 - RC Groups
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Archive for October, 2011
Posted by joebarteam | Oct 13, 2011 @ 09:31 AM | 31,762 Views
In this mini 'how to' I try to show how to tune the behavior of a MegaPirate multicopter. This 'how to' is based on the excellent OpenPilot instructions.

Because the MegaPirate is suitable for a wide selection of frames, controllers and multi sensor the defaults in the code needs to be tuned for your specific platform.

Most MegaPirate users, or (it's parent code) the ArduCopter users concentrate on the stable mode only. I tend to take another approach because of the nature of the PId loop.
First the inner loop or rate is used and when in stable the outer loop will kick in. In this picture you can see the structure.

Because of that, I like to tune the rate (acro mode) and make it as flyable and stable as possible. It will however not level, thats the stable mode.

Rate (acro) mode tuning
Rate will only use the gyro.
In the first step, concentrate solely on the rate 'P', 'P' is the rotation value to counter external rotation effects caused by influences like wind for example. The gyro will detect such rotations and feed the control loop.

High frequency oscillations will occur when 'P' is to high, if is feels to sluggish or it is not flyable at all (see vid) it is to low.

The rate 'I' value is normally not used, but as I explained, I like to tune the rate as good as possible so the next step is tuning the rate 'I'
The 'I' in rate is used for angle hold, if it is 0 or close to 0 the copter will never hold an angle and swing around it's axis. Increase...Continue Reading