Crashed when testing RTL / Stabilize mode

Hello,

I just finished building a 250 X quad a few days ago, did some short flight on Stabilize, and today I decided to try the Loiter / RTL mode and crashed it. I am pretty new to this so some help analyzing what I did wrong and/or what failed would be great!

Here's the logs 2017-04-13%2021-55-55.bin 2017-04-13%2021-40-42.bin and output of the loganalyzer:

Vehicletype ArduCopter
Firmware Version V3.5-dev
Firmware Hash 0c1f2ba1
Hardware Type
Free Mem 0
Skipped Lines 0
Test: Autotune = NA -
Test: Brownout = GOOD -
Test: Compass = FAIL - FAIL: Large compass offset in MAG data (X:4095.00, Y:386.00, Z:0.00)
Large change in mag_field (286.83%)
Max mag field length (555.35) > recommended (550.00)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERRs found: FLT_MODE CRASH
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.48, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = WARN - Motor channel averages = [1356, 1404, 1317, 1364]
Average motor output = 1360
Difference between min and max motor averages = 87
Test: Parameters = GOOD -
Test: PM = NA -
Test: Pitch/Roll = NA -
Test: Thrust = NA -
Test: VCC = GOOD -

Thanks!

Replies

Marisela Shaw May 19, 2022 at 1:17pm

Thanks for the info.
Khushal B April 18, 2017 at 4:36am

Michael Burmeister said:

It looks like it was flying good and while in loiter mode you selected RTL. When you select this mode the copter started to gain altitude as the RTL height is set at 15. The thing with a 250 size quad is that its small and seeing it flight up is scary.

Anyway since you were in Loiter mode the throttle was at minimum and when you switched to Stabilize mode as it was climbing it had to cut the motors and began to tumble under the lose of power. It was not able to recover from this fall.

Since the throttle out seems low it looks like it did not have enough time to learn where mid throttle should be which is the case with small over powered units.

I have my small 250 set to Land mode and not RTL since I don't like to see it fly that high being so small. I leave RTL to the big boys that go out on missions.

This is exactly what happened to me on my first flight - panicked seeing my F450 flying up after going into RTL. Setting to Land mode instead of RTL sounds safer, I think I'll do that as well.
Michael Burmeister April 14, 2017 at 10:39am

Right looked at the RCIN for number 3 which is throttle.

Normally when you purchase a flight controller there is just some default code on it. You use Mission Planner to load what you type of device your going to install it on. If it's a ready to fly then it should be loaded from the factor.

You can't backup the firmware. Only load new onto it. I can check to see what version of dev code you have and provide a link to it. Don't know if that was test code to checkout the flight controller or not.

Reading logs takes a little getting use too. There are things I still don't know.
Cash Lo April 14, 2017 at 7:56am

Thanks for the reply!

That's the version the pixhawk comes with, should I update from the mission planner? I really just want a stable quad, no need to cutting edge functions for now. Also, is it hard to backup the firmware? Is it necessary to backup before I update?

I think you are spot-on about what happened, I remember changing throttle and seeing no response so I flipped the mode switch (bad idea), did you figure out from the RCIN graph? Trying to learn how to analyze the log :D

Michael Burmeister said:

First off you are running beta code. 3.5. dev

It looks like it was flying good and while in loiter mode you selected RTL. When you select this mode the copter started to gain altitude as the RTL height is set at 15. The thing with a 250 size quad is that its small and seeing it flight up is scary.

Anyway since you were in Loiter mode the throttle was at minimum and when you switched to Stabilize mode as it was climbing it had to cut the motors and began to tumble under the lose of power. It was not able to recover from this fall.

Since the throttle out seems low it looks like it did not have enough time to learn where mid throttle should be which is the case with small over powered units.

I have my small 250 set to Land mode and not RTL since I don't like to see it fly that high being so small. I leave RTL to the big boys that go out on missions.
Michael Burmeister April 14, 2017 at 3:00am

First off you are running beta code. 3.5. dev

It looks like it was flying good and while in loiter mode you selected RTL. When you select this mode the copter started to gain altitude as the RTL height is set at 15. The thing with a 250 size quad is that its small and seeing it flight up is scary.

Anyway since you were in Loiter mode the throttle was at minimum and when you switched to Stabilize mode as it was climbing it had to cut the motors and began to tumble under the lose of power. It was not able to recover from this fall.

Since the throttle out seems low it looks like it did not have enough time to learn where mid throttle should be which is the case with small over powered units.

I have my small 250 set to Land mode and not RTL since I don't like to see it fly that high being so small. I leave RTL to the big boys that go out on missions.

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Crashed when testing RTL / Stabilize mode

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