Hi Everyone,
There are a couple of people I know who have already faced this in RC5. In 3.0.1 I see that I do not get issues, so posting it as a separate forum.
I am using sonar (XL-EZ0, MB1200) + baro on my APM 2.6. Using 3.0.1 RC5, I have attached the logs for perusal. "This did not happen before" and happens more with slight winds.
Note: There were slight traces of wind, but this Up-Down movement is very consistent. Goes up and down by same distance every time.
The only thing that I can think of is 'Thr`Mid' set at 596 for hovering, which I have tried to vary in earlier tests with similar results.
Can somebody have a look and suggest why this happens, from the log?
IMU: Vibrations controlled fantastically on my setup.
CTUN:
SonAlt Vs BarAlt: Reading correct values as it jumps and tries to correct.
ThrIn Vs ThrOut, you can see sudden dips. ThrIn (red) remains constant. See the green bars dipping? That is the problem.
Something with 3.0.1 RC5?
Replies
This is the test I did of the sonar. Not perfect but seems to work!
I tried -rc7 yesterday and I needed to reduce the SONAR_GAIN to 0.8 but then it worked fine. I'm using a 3dr quad with an Maxbotix MB1260 (aka XL-EZL0) sonar.
It's reaction time is a little slow but that's perhaps better than it was in AC3.0.1 where it was far too fast.
On the bench I am getting accurate readings. In flight up & down with motors cutting out etc.
I've added all the recommended filtering. Tried two different (same model) Sonar modules.
For now the Sonar is unplugged & disabled.
AFAIK, 3.01 main release for sonar was perfect.
Stable release was stable as the name suggests!
I saw your markings on the graph, the copter swung between 0 altitude to some meters above. It was pure oscillation (like overshoot of some P term trying to correct the altitude error). During that time 'Throttle input' was unchanged. Touching the ground might have slowed down the motors just to rise it up again.
I will reduce the sonar gain and test, maybe do you believe that is the cause for this behaviour from the logs?
Btw, the other flights during the same day (over 10 mts) did not bring about this. It was around 5 - 10 meters height that this happened in both Althold and Loiter.
Thanks again,
Shyam
I think the little spikes in the motor out could be caused by the copter hitting the ground. It looks like it was going up and down, was it actually hitting the ground at times?
Shayam,
We did a bunch of work in AC3.1 to improve the sonar altitude hold. I think what's happened is we've got the SONAR_GAIN too high. I think instead of 2.0 it should be much lower like 0.2. It's actually possible to tune it with the channel 6 tuning knob if you have one.
As seen from the log this sudden jump without user input looks abnormal. The jump was constant ~4 meters and that does not seem like correction. Mybaaro is well protected and black foamed.
Hope someone can shed some light.