Howdy. I am flying a quadcopter with a Pixhawk and am having a very strange problem with the copter losing altitude in Loiter or Auto modes. I have included a link to a log file from some testing this weekend. I started the mission with a short automated flight and then had the craft hover in Loiter to watch its behavior and test out flight time. The hover is quite stable, but occasionally the copter would just have a big drop in altitude then come back up to a hover in Loiter. These can be seen in the flight log is big drops in altitude and also big spikes in roll and pitch. We have had similar experiences flying long auto missions where the copter just suddenly drops a few meters then gets back up and keeps going. It is quite windy where we are flying right now and I don't know if it is affecting the Baro. I've checked vibrations and there isn't really anything out of the ordinary except when the copter drops there is a large spike in Acc-Z, but I think this is a symptom of the big drops and not the cause.
What is interesting is that the logs are reporting that the copter is switching between Loiter and Stabilize as it goes through these drops. Indeed there are also large drops in ThrIn at the same exact time, except that I was doing nothing with the controller when these things were happening and was just sitting about 30m away watching the copter. I had the controller in my hands but was not moving any switches at all.
Not sure what other information is requested with a post, I couldn't find posting instructions. Let me know what else you might want. We have the new EKF turned on. I am going to test out turning it off this morning to see if I get similar performance.
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you can solve? I have the same problem. Follow the LOG file in case someone can help.
Frame: S500
Motor: S3508 700kv
Prop: 12x3.8
Controller: Pixhawk firmware 3.3.3
Battery: 4S 4000mAh
2016-10-25 15-44-32.bin
Nice 35 minute flight. It looks like from the logs that the motors started hitting there maximums and finally it looks like motor 1 failed.
From the log I can see that Desired Pitch and Pitch went in opposite directions. I had to truncate the log so I could focus in on just the last part of the flight.
Looks like you need a new radio. Throughout the log the radio cuts out and this puts all the values to zero and also switches mode back to Stabilize. It's not long enough to signal a failsafe but long enough to mess with the flight.
Thanks, I was wondering about that too and wondered if it might be the radio. I have another identical one and will try that out.
Quick followup. So switching controllers appears to have gotten rid of the problem of the signal cutting out and the altitude dropping, but now it seems that something else went wrong. I was at the very end of a roughly 35 minute practice mission and the thing just decides to drop and crash. No idea why it just gave up. Here is a link for the log from that flight. I am still trying to piece it together myself.
https://dl.dropboxusercontent.com/u/979016/81.BIN