Have anyone else noticed that the pitch axis of the M4P is unstable at different speeds with the battery plus on it?
The causes significantly decreased flight time. Is there any way we can change the pitch PIDs?
A changed CoG shouldn't make the pitch axis instable (if the motors doesn't reach max revs)... if heavier in the rear the Flight Controller will command higher revs on the rear motors to generate more thrust to compensate & position the drone in the commanded tilt angle....I figure it was designed around the original battery and the larger batt changes the balance center point.
Maybe.
If you share the flight log from a flight where this happens we can clearer see all that happens.
Go here & upload the log which is stored in the screen device you flew with --> PhantomHelp Log viewer...I’ve never pulled a log, so it’ll be good practice on that for me.
This is similar to behavior seen with an Avata that had been modified with larger motors. I'm assuming your Mini 4 Pro is not modified? Have you replaced some props recently?This happens to me as well, but IMU calibration did not help. It starts oscillating in head wind but it will not stop on its own and I have to reduce throttle or completely stop for it to regain balance.
Here's the flight log: DJI Flight Log Viewer - PhantomHelp.com
Timestamps of the issue:
1:22 - 1:29
6:02 - 6:14
20:07 - 20:10
20:36 - 20:42
Does anyone has any suggestions what could be the issue, other than this unit just being a dud?
You're welcomeThank you for uploading the log. I had the issue again last weeks db have not figured out how to download and lost it from my work IOS setups.
It is a stock, basically new M4P. This started happening from the first flight, it's not something that appeared after prolonged use. Props are undamaged and screws are tight. On this flight I used Plus battery. The same issue also appears with the normal battery, but it is less frequent and less prominent.This is similar to behavior seen with an Avata that had been modified with larger motors. I'm assuming your Mini 4 Pro is not modified? Have you replaced some props recently?
Loss of control after upgrade
Looking at the first example, [82 - 89] secs, it can be seen that both pitch and, to a lesser extent, roll are oscillating at about 2.5 hZ. Further, there is a phase difference of about 90°.
View attachment 173997There are other events where the oscillations weren't as extreme as the ones you cited; e.g. [1213, 1216] secs. The cited events all occurred when flying into the wind while the Mini 4 was close to max pitch forward. It would be interesting to see if this happens flying backwards.
My advice is to contact DJI and return for either repair of replacement. You might want to first check the props; no nicks, no loose screws, etc.
...Does anyone has any suggestions what could be the issue...
This is similar to behavior seen with an Avata that had been modified with larger motors.
My advice is to contact DJI and return...
I think this is a PID tune issue...I also remember this problem from my M4P...So it's a general problem, not just some individual drones.
You could try a PM to one of the moderators on the DJI forum. Also try contacting DJI tech support via email, phone or chat. Per @slup 's post I suspect it's fixable with a firmware update. Good luck.Thank you @BudWalker for the log analysis and thank you @slup for your explanation. Because sending drones back from my region is painful I would like to make sure that this is not a firmware / design issue, and not just my unit. There are at least 4 of us here that are experiencing the same issue. If we attract enough attention on the official forum maybe DJI engineers will take a look at these logs and tell us if it is fixable by a firmware update, or we actually ended up with faulty units. I previously crated this thread on the official DJI forum, but still did not get any response from DJI: Mini 4 pro oscillating
I agree. It might help if others who experience this issue send their logs to the following official DJI forum thread: Mini 4 pro oscillatingIf it's a matter of PID tuning as @slup outlined, and I agree this is 99% likely what the solution is, we'll see this fixed in a future firmware update. Since we know the battery type is detectable, this may simply be a matter of separate PID values for the different batteries.
If this is the problem/solution, any help we can give DJI in reliably reproducing the problem will make a big difference. PID tuning is near impossible if you can't measure the effect.