ArduPirates Spreadsheet survey

[Helicoblast]

Hi Captains,

I've worked on a spreadsheet with two goals:

1. Allow everyone who want to compare with other setups
2. Help the dev team to set default PID's as better as possible.

The link to the spreadsheet:
https://spreadsheets.google.com/viewform?hl=en&authkey=COzb5NMG&formkey=dFF5NmlCSTNFYlIwS2JRSFBNdW82YXc6MQ#gid=0

The link to the raw data:
https://spreadsheets.google.com/ccc?key=0AksfGpFikpVAdFF5NmlCSTNFYlIwS2JRSFBNdW82YXc&hl=en&authkey=COzb5NMG#gid=0

The link to the summary:
https://spreadsheets.google.com/gform?key=0AksfGpFikpVAdFF5NmlCSTNFYlIwS2JRSFBNdW82YXc&hl=en&authkey=COzb5NMG&gridId=0#chart

Here are some informations that spagoziak, multiwii team member, sent
to me:

"I think PID is influenced by these things:
Boom Length
Symmetry of the frame
RPM (as kv)
Propeller length
Propeller pitch
Propeller weight
Battery discharge rate
Frame rigidity
All-Up-Weight

Some of these things really aren't practical to measure, but there are
certainly a few items that can be easily quantified and understood. I
think there is a very meaningful relationship between boom length,
prop weight, pitch, and rpm. These four aspects really seem to stand
out as the elements that make PID more or less effective.

Boom length (from center to motor) acts as leverage; the greater the
distance from center to motor, the less effort the motor has to make
in order to affect the aircraft's attitude.

The greater the range of RPM a motor has, the greater range of speeds
the motor must cover in order to meet the demands of the PID
controller. For example, if a 1000 kv motor turns at 11,000 RPM @
11.1v, the motor has to travel 5500 rpm in each direction if hover is
around 50%. If a 2200kv motor is used, then the motor must be able to
travel 12,210 rpm in either direction to accomodate the demands of the
PID controller. Something like that would require a very high-torque
motor or a very light propeller. In short, higher RPM's lead to less
responsive copters because the props can't match the thrust
requirements of the PID controller.

As mentioned above, propeller weight would directly affect the motors'
ability to change speeds quickly enough to do as the PID commands.
Also, on CW/CCW quads, weight would affect yaw authority since yaw is
generated from torque of the opposing planes.

Prop Pitch comes into play by determining how much correction the PID
needs out of the motors in order to get what it needs, since thrust is
the PID's only tool in correcting attitude. If a deep pitch prop is
used, the PID can get a tremendous change in thrust without changing
speed too much. Pitch would greatly and directly affect PID tuning.
I feel like there is a proportional relationship waiting to be
discovered between these four elements. Being able to make a
multirotor planner using a formula would be revolutionary, but it's
well beyond my skill!"

[Daniel Saez]

Cool, here we can gather a large amount of usefull info, and it can be
quickly accessed.

nice job!!

2011/2/14 Helicoblast <bati...@yahoo.fr>: