That is actually a quite good (low) noise level. There’s no issue there.
Hello,
After a few attempts at the PID tuning process and searching through many topics on the ArduForum, I am still struggling with my rover.
As you can see, the rover runs straight and stays on course during the mission. However, I am having issues with slow and precise movements. My PID control graph fluctuates a lot when I try to move forward or turn at very slow speeds, which is necessary to reach points estimated via RTK GPS FIX.
Here you can find the video and log file:
https://drive.google.com/drive/folders/1TATglKv18NbIB_SIgg5McM5W7Qh9yZWz?usp=sharing
hi can you check my issue again ?
From your logfile, you’ve increased MOT_THR_MIN to 10. Any reason why, since in your previous comment a lower value reduced the shaking?
Before I send a log file, I made several tests with MOT_THR_MIN – there is no impact on slow movement. In all cases, PID_achieved and PID_desired charts look the same (high oscillation for PID_achieved but no smooth movement).
If you want, I can change it again and send another log, but there is no impact on slow-speed movement. What is more, in manual mode, I can do perfectly slow turns and forward/backward rides. Therefore, I am thinking the PID loop is an issue.
Maybe I should tune it again, but after more than 20 attempts, I have no idea what I should change to match this slow movement with straight steering at a speed of 1.5 m/s.
I had a similar issue with a vehicle “shaking” at standstill in ACRO mode. In my case I increased MOT_THR_MIN from 0 to 5 and the issue disappeared.
Are you using the “quiktune” lua script for tuning, or doing it yourself?
Looking at your params:
- You’ve’ got
ATC_BRAKEset to 2, which is an invalid value. This should be 1
Looking at the bin log in your previous post, I note that the shaking only occurs in AUTO mode. Is that what you saw too? If that is the case, I’d recommend resetting the PSC_* parameters back to default (these control waypoint tracking) and seeing if that helps.
Thank you, StephenDade,
As you suggested, we changed ATC_BREAK to 1 and reduced MOT_THR_MIN to 5.
We are tuning the rover by ourselves. However, we tried QuickTune – it took more than 15 minutes and was still working on the first parameter without success.
That is the steering tab. Maybe we have poor steering tuning, and that is why we are struggling with slow movement and shaking?
https://drive.google.com/drive/folders/1GRdTm84gkYfGaJXsquvf_p5IfyLsTjf8?usp=sharing
Here you can find more log in Acro and Auto mode.
The main issue now is jumping-move at really slow speed ( 1550/1575 PWM in servo tab) it happend in forward move and in turn move and in pivot.
Do you have any recommendation ?
So the Quiktune is showing the error message “RTUN: Increase steering”. So you need to configure the vehicle to move (turn) faster in the circle. This can be done via increasing the circle speed or decreasing the circle radius.
What you actually want to graph is STER.TurnRate and STER.DesTurnRate. Unfortunately, the items you graphed have different units (Onboard Message Log Messages — Rover documentation) and won’t show correctly.
I would suggest trying:
- Reducing ATC_STR_RAT_D = 0
- Reducing ATC_STR_RAT_P = 0.1 (or maybe 0.05 if there’s still shaking)
- Increasing ATC_STR_RAT_FF = 0.6