http://www.rcgroups.com/forums/showp...87&postcount=4

A collection of links about PIDs and tuning

1) http://www.rcgroups.com/forums/showp...postcount=7460

2) http://www.multiwii.com/software

PID controller involves three separate parameters: the term Proportional, the term Integral and the term Derivative. The variation of each of these parameters alters the effectiveness of the stabilization.

Applied to a multirotor, the coefficients of these parameters can be translated by their behaviour:

Proportional coefficient: alone, it may achieve stabilization. This coefficient determines the importance of action on the engines in relation with the values measured by the gyroscopes. The higher the coefficient, the higher the tricopter seems more “rigid” versus angular deviation. If it is too low, the multicopter will appear soft and will be harder to keep steady. One can “feel” this setting by handling the tricopter and trying to change its orientation: the higher the parameter, the higher the opposition is important. In practice, this parameter must be set alone and increased up to be the limit for obtaining small oscillations. If too high, the system becomes unstable by amplifying the oscillations.

Integral coefficient: this coefficient can increase the precision of the angular position. In practice, when the tricopter is disturbed and its angle changes, the term Integral remembers the disruption and apply a correction to the engines to get the right angle. We can see this term as an heading hold factor. Typically if

...Continue Reading

Frame from http://www.hoverthings.com
Controller from: http://witespyquad.gostorego.com

Some photos
Quad X: http://dl.dropbox.com/u/788548/Quadcopter/IMG_1549.JPG
Quad +: http://dl.dropbox.com/u/788548/Quadcopter/IMG_1560.JPG
Quad + with stacked 11x4.7 and 10x7 APC props on right and left arms: http://dl.dropbox.com/u/788548/Quadc...%2047%20AM.jpg

Some videos
Backyard flying: http://dl.dropbox.com/u/788548/Quadcopter/IMG_1552.MOV
Backyard flying (Quad + with stacked rotors): http://dl.dropbox.com/u/788548/Quadcopter/IMG_1701.MOV
Open field flying: http://dl.dropbox.com/u/788548/Quadcopter/IMG_1553.MOV

I've used these motors on 2 quads (frames from http://www.hoverthings.com) and have been pleased with their performance. I have a third build planned with these motors as well.

http://montorc.com/M2814Shaft.aspx

For those using the Quadrino MultiWii controller from witespy (http://www.rcgroups.com/forums/showthread.php?t=1438619), here is a record of the PID changes I have made for v1.7 (Quad X) and v1.8 (Quad X and Quad +) of the MultiWii software.

https://docs.google.com/spreadsheet/...Xc&output=html

You can get the controller here (2 versions, basic and advanced, are available): http://witespyquad.gostorego.com/

I've used these ESCs in 2 builds (Fyetech FY90Q and Quadrino MultiWii) and have been happy with their performance.

User guide: http://dl.dropbox.com/u/788548/Quadcopter/MayTech.pdf
US Source: http://montorc.com/MT30ABEC.aspx