Re: [Paparazzi-devel] Strange throttle behavior

[Eduardo lavratti]

Hey man ... take care with your tests !
This props and motors are very POWER and DANGEROUS !
Take a look at this pictures  http://brquad.blogspot.com/2011/04/little-acident-with-my-big-hexa.html
This accident occurred when i make some tests with my big hexa whit same motors and props.
Never make this tests with children arround.
Well, for the JUMP problem reduce the "guidance_V / hover_KP" and make a test.

Make the same for wooble. Reduce the P & D GAIN parameter for Theta and Phi . You see this values in STABILIZATION_ATTITUDE section.
Reduce P for 300 and make a test.

Stay sure that your props are very well balanced or your lisa board have a good vibration isolation.

When i make my first fly using lisa/m i have similar attitude on me small octo (5"props) and on my quad (8" props)
after i balance the props and make a good vibration isolation all problems are solved.

Regards and sorry for my poor english.

Eduardo Lavratti
Brasilian UAV developer.

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Date: Sun, 18 Dec 2011 20:38:21 +0100
From: address@hidden
To: address@hidden
Subject: [Paparazzi-devel] Strange throttle behavior

Hi

I have been noticing what seemed like a lag in throttle control though I wasn't 100% sure till my first test flight today (octocopter, lisa/l, spektrum satellite receiver). While on the ground I don't seem to notice this effect but when holding it above my head or lifting off strange things start to happen.

When holding it above my head changing the throttle on the sender seems to take a second or two till it happens on the copter. I have also noticed what seems to be a general increase in throttle all of sudden, not just to correct attitude but like a it wants to pull up and away. 

When I tried the first flight today I got a bit of a shock when I wanted to just lift off a bit then set down only to discover it did not want to respond to the fact that I had returned the throttle back to zero and skipped off across the garden. In the end I had to flick the kill switch. Pretty funny after the event. I have a video if you want a laugh here. 

You will see the props rotating at minimum speed (zero throttle on the sender) after arming. I assume this is correct? One of the props isn't rotating properly and I suspect it might have a problem and need swapping with a spare (it has a bit more resistance to the hand when rotating than the others) but I thought it might be OK to try a small hover anyway.

Any ideas what causes this kind of throttle behavior? Pitch and roll seem pretty responsive. Here is the aircraft config.

Thanks

Simon  

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