@xfacta I am expecting a suggestion from you, will you please have a look.
The fact that you have not addressed vibration by any other means than damping the mount suggests that you have not addressed the root cause. As such, I think you are getting somewhat predictable disastrous results. As Shawn and Brandon have stated, over-damping is not the solution here.
In fairness, I did not review the logs, just the overall context of the posts.
There is a lot history in this thread Iâm not going to review but in that last log your Roll input, and Pitch for that matter, set up an increasing oscillation indicative of the Rate P&I values being too low. I would put Rate Roll/Pitch kP on an in-flight tuning pot with the low end at default and the high end double that and do some testing. But, thatâs just how I do things; you need a good handle on manual tuning to proceed down that path. And, itâs time consuming. But if you have been at this for 2 months I suppose you have the timeâŚ
Thank you, but I did manual tuning before proceeding to autotune but in alt hold it was stable when I fly in loiter it started oscillating. Later I did quicktune in loiter mode and followed autotune. As a see I didnât get proper tune even though being run autotune 2 times on each axis .I got PIDs too low later by manual I increased PIDs and made the drone stable. I the second log which I have posted, I have done maneuver for all the axes it was doing good. Later I landed and after Reboot again I tookoff to see performance, in loiter mode slightly I gave roll input at 3m altitude. It started oscillating and toppled and crash. I didnât get when then drone did stable flight test in 2 nd log with the same parameters after reboot it crashed.
I cant see whatâs causing the oscillations in that latest log, But I can see yaw is drifting ahead of the desired yaw heading without any yaw stick input. To me this says there is a physical yaw problem, but I dont see in the motor outputs like we do with a twisted motor mount. Maybe props are in the wrong order or something odd like that.
Get a video of the MissionPlanner motor test when you press âAll in sequenceâ and lets see that.
This is the order (A, B, C, D) and the rotations:
Yes I have observed yaw drifting after takeoff as I thought it might be because of internal imu causing the issue or the yaw angle is 6.8 . If I keep yaw angle to default value drifting was not observed. If you see the second log there is also a yaw drifting but while takeoff from ground there is a slight oscillations after which it was stable.
Motor order and directions are correct before takeoff we did motor test on the ground . I didnât understand after takeoff when I gave slight roll input.it suddenly oscillated and crashed.
In my opinion, this carbon fiber eggshell looks nice but may not be rigid enough.
Maybe redo the accel calibrations - use a square or triangle to get the copter quite vertical where required.
After that whole procedure set the copter as level as it normally is on the landing gear. now pack under the landing gear to get the copter as level as possible across the tops of the motors - left to right, front to back, diagonals.
In the accel calibration screen press the âCalibrate levelâ button.
You can use a spirit level, I made a very light weight level with some angle aluminium and a string-line bubble level.
I have thought of this idea to mount this laser level on mini tripod to adjust different high to cast a horizontal laser line.
We have used it to cast lines from ceiling to tune our big drone XY-CG with our customs make CG machine.
By this time we have added 10 layers carbon fiber and manufactured shell by vacuum infusion molding and shell come out rigid with 310gms. Even after making the shell rigid and did followed the autotune procedure, while doing PID quicktune Roll PIDs are getting less and Pitch PIDs are high that mean Roll P&I is 0.113 and D is 0.0031 and for Pitch P&I is 0.210 and D=0.0091 which is making tight tune on Pitch axis and loose on Roll axis making oscillations in Roll. Moreover when changed to althold mode arm starts oscillating very badly.
Later keeping default values after applying did autotune on all axes but no proper tuning found. In loter mode the copter is oscillating.
Motor 230kv tmotor. arm tube 16mm outer dia and 14mm inner dia and arm length from frame 13inch. Is anything causing issue here. And one more thing distance between landing gear at back 58cm, front 59cm, left 56cm and right 57cm, will it causes any issues.
Below I am attaching logs of autotune done in roll and pitch axis.
In default values and after PID Quick tune there we observe no yaw drifting but once autotune is done in all 3 axes after takeoff. I observed yaw drift without any yaw commands. I thought it might be the issue of angle P. once we keep the yaw value default no drift will be observed. its been long time we are making the frame rigid and did followed the procedures but once autotune is done , we are not getting tight values for it. but manually increasing or decreasing PIDs and making tight tune. but id we increase D value more observing oscillations in arms. And if we do Quick tune pitch is getting tight tune but not roll. Is there any issues with firmware or design. Should I update to the latest firmware?
I think your arms are too small. I would expect at least 25mm OD for a 24â prop.
Is anything can be done in current design, rather than changing the arm dia?
This is not the most efficient in terms of weight but you could try using some thicker 16MM rods. Something like 16mm OD / 8mm ID would be more similar to a 25mm OD / 23mm ID tube.
The problem I am thinking here (esp since you mention vibration on arms) is that the arms are too long and thin causing some beam deflection and reverb. I have seen this on a larger aircraft where going from 25mm to 30mm tubes solved the vibration problems we were seeing (30" prop hexacopter).
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Thank you. Today we tied a string on the sidewards and back , did autotune and the results were yes , it came good and it did tight tune on both the axes. So we are planning to mount a 2mm carbon plate on sidewards like a arm support and do testing.
Nice yeah some tensioned string/line between the arms would also work. Just need to make them stiffer somehow.
We want add 2mm thickness carbon fiber sheet on sidewards which makes copter to look as wing. will it work out? @manavgandhi17 what is your opinion on this?
The main downside I could think of is that the airflow running over the arm is going to hit some flat plates - so that may lead to even more vibration vs just a smooth tube. Whatever you can do to make it stiffer would be great. Could you find a tube with 16mm ID that you could slide over the 16mm OD tube?