Troubleshooting Tips for Motors/ESCs/Instability Issue?


At the start of an AUTO flight today IRIS took-off and didn’t sound or look stable at all. There was a 5-10Hz whoop-whoop propellor-ish noise (technical definition); it was nearly like a prop was loose or an ESC was playing up. The little guy got all of 2-4m into the air when he flipped upside down and tried to burrow his way back to Mexico. One tarot gimbal and a couple of props: required.

Something a little strange though: Now when IRIS is armed, the props don’t spin. A little RC throttle causes one of the props to spin up, a little more causes maybe another two, and finally the last, however they’re all over the shop. Sometimes different props will spin at different rates, and there’s no way it could take off without flipping over.

We’re going to have a look at the ESC board tomorrow, and assuming no obvious physical damage we’ll try recalibrating the ESCs. If that doesn’t help we’ll flash the firmware and the parameters and go from there.

What seems strange to me though, is it’s like the parameters file, or esc calibration, or similar, has changed. (We had a perfectly normal (short) RC flight only minutes before). I know you can turn the ‘props-spin-when-armed’ down or off, but I was under the impression that settings and parameters don’t respond to physical encouragement. Can ESC calibration be ‘knocked’ out of sync!?

I’m in a bit of a rush what with thesis due dates looming, so I’m posting this sans-logs for now. I’ll do what I can to get a hold of the logs first thing tomorrow. There’s also a video from the GoPro onboard that I might be able swing this way.

For now - any troubleshooting tips for issues like this would be super appreciated!

Hi explode,

The ESC calibration should fix the motors spin when armed issue. A crash can’t change the parameter but as a reference the default parameter value is this MOT_SPIN_ARMED,90

regarding the “5-10Hz whoop-whoop propellor-ish noise”, I would recommend you to check the propeller fasteners (like these ones: … stener-kit) are firmly assembled to the motors, and the motors to the arms.

Thanks Rogelio.

The ESC recalibration did the trick. Back in the air first thing this morning. Gimbal seems ok too, just needs a lot of glue.

We couldn’t see any physical damage to the ESC board or anything else internal. Motors are still firmly secured to the arms.

Could well have been a faulty prop / fastener - our pre flight checks definitely cover tightening props but from now on we’ll also do a manual throttle check to make sure there’s no significant oscillation prior to auto take-offs. I don’t really see how this could change the ESC calibration, unless something went strange with power on impact.

Unfortunately the mission planner logs stop prior to this flight, and IRIS was flashed to 3.1.3 before I had a chance to get at the onboard ones.

Here’s the video anyway.