Almost lost an IRIS today

Was performing a demo today when about half way through the flight I noticed that it didn’t seem to respond to my control inputs. I switched from Stab to Loiter then back to stab and tried to bring IRIS back but it seemed like it was being pulled away from me. I switched to RTL and things seemed to get worse so I went back to Stab as i started to run towards the IRIS thinking it might be signal related.

After switching modes several times while continuing to try and bring it back toward me, I was able to gain some control and bring it down. Not a very good flight or demo :frowning:

I have attached the log from the flight hoping that one of you programmers can make some sense of what might have happened. I have some theories but I don’t want to sway yours.

Any assistance would be appreciated.

So the only thing that jumps out at me is if you map Pitch vs Desired Pitch…

It’s like it doesn’t know what level is with regard to pitch. It looks like you were fighting that the entire flight time.

Your Z vibrations are whack too.

That and you asked for Auto-Mode and it couldn’t give you that. No mission waypoints? I don’t know what causes Err: Flight_Mode:3, other than what the documents say.

10: Flight Mode
ECode 0 ~ 10: the vehicle was unable to enter the desired flight mode
(0=Stabilize, 1=Acro, 2=AltHold, 3=Auto, 4=Guided, 5=Loiter, 6=RTL, 7=Circle, 8=Position, 9=Land, 10=OF_Loiter)[/quote]

Yes the Auto mode was my mistake trying to switch modes and recover. I had no auto points set. After leaving the area, I notice a cell tower near by as well as a radio tower of some sort within a mile of the field were I flew.

I had just demo’d a Phantom Vision which flies on 5.8 ghz with no issues but I did have an issue with the wifi video from the Phantom which relays on 2.4ghz. The signal froze half way through the flight.

I didn’t think much of the Phantom issue until I flew the IRIS with the stock 2.4 ghz radio.

Hi, looking at this log now.

First thing I checked are vibration levels. X and Y seem OK, but Z is… quite extreme. Do you know what’s going on there?

Another thing, is that your #Sats is low, and HDOP is high for the first 1-2 minutes of the flight.

As mdisher mentions, the Pitch vs. Desired Pitch is really pretty bad. I’d almost call it out of control. Do you know why? You mention having a camera on it, is the CG balanced? It looks like you have to keep pulling back on the stick to try to get it to level out, and it’s not doing a good job. So it might be “flying away” simply because it can’t keep the pitch, so it keeps nosing down, and away from you. This would also make auto modes behave really badly.

Your Rate Pitch Imax is at the default of 500. I would try increasing that in steps of 500 until it hovers level with your hand off the stick.


This IRIS flew great the previous night with no issues. The only things that changed where the location and I did have a GoPro mounted on the stock mount on the nose but that was it. Should the IRIS have been re-calibrated some how when a fixed camera or the factory gimbal kit is installed?

This seemed like more of a control issue as it would not return to me no matter what control inputs I gave it.

It probably does need to be retuned when adding a large mass to the front. It does make a difference. Even just increasing the Imax will help a lot, without having to retune the entire PID.

What is the best way to accomplish this?

Just go into the PID tuning screen and increase the Rate Imax to 1000, then 1500, etc. if you need more.