Hi all,
I am currently running some tests to around a quadcopter to be used in fire-fighting applications.
for this i need to measure the effect of water ejection off the quad
Is it possible to remove the stabilisation to the extent that the APM will not correct for anything? if so how?
at the moment i have the quad being displaced translationally but the system is corrected about the pitch axis, so determining real effects is difficult. I wish to remove this correction.
any help is greatly appreciated
Replies
I understand you want to test recovery from being hit by a water stream.
Be sure to use propellers that can handle the water stream/spray whithout breaking.
The easiest/best method to *simulate* a situation where the UAV is hit in the air, not too damaged, and thrown out of control, is simply to do this:
Fly in manual mode, during different maneuvers (roll/pitch rate and speed) - suddently bring the throttle to zero, and restore throttle or just switch to alt.hold or loiter after 0.5..2sec. Depending on flight style and what you do, the UAV will assume a unusual position, from which it must recover.
This is a hard test, it will verify the effects of CG, power reserves, ability to spin up stopped or reversed propellers.
A water jet could easily be able to reverse-rotate a propeller, be sure your ESC/motors do not have any sync-issues.
If you do not want to test full stop, only stabilization loss, do the same, but with MOT_SPIN_ARMED set, the motors will not *stop* but will not stabilize, and let the UAV tumble in the air.
Test gradually and at good altitude.
Be warned, the most dangerous test is the one that may appear "safest":
If you just let it hover, then cut throttle it may fall stright down (no tumble), all props can reverse-rotate and gain speeds motors cannot overcome due to bad sync, in such case a hard input until 90degree roll/pitch helps, but it takes time(altitude).
So; loosing control while having a roll or pitch rate is actually to recover from.
Happy testing.
I appreciate your reply,
My initial description was poor.
There is a water cannon on my quadcopter. The waters point of origin is on board.
I wish to gauge disturbance to flight this mass ejection causes.
however the quad alters pitch slightly during firing.
It is important flight controller makes no adjustments as the tests will be useful to build and validate a kinematic model.
oh.
No adjustments, would make it crash (depending on the CG and thrust vectoring) - multirotors adjust thrust distribution "all" the time.
Then I'd suggest that you just hang it (disarmed) and do the measurements while ejecting water.
Also, I think you'd be better off by pitch stabilizing the nozzle, rather than change the airframe stabilization.
Pitch stibilization of the nozzle can be done as easy as camera stabilization.
Finally, you could add a little code that set a certain pitch the moment before water ejects to reduce the "recoil" effect and reduces delay until steady position hold.
Sorry about that
Is here any better?