Path Deviation After Turning: Planned Path is Normal, Straight-line Motion is Fine, but Robot Starts Drifting After Turns

[LPARKOUR]

I'm facing a very frustrating issue with my robot's navigation and I'm completely stuck. I've run out of ideas and would be incredibly grateful for any troubleshooting suggestions.

The Problem:
My robot plans a global path correctly and can follow it perfectly when moving in a straight line. However, immediately after making a turn, it starts to deviate from the planned path. The deviation seems to accumulate, causing the robot to drift away from its intended route.

What I've Checked/Tried:
The global path planning appears to be fine.
Odometry seems stable during straight-line motion.
I wanted to provide a full bag file for analysis, but encountered an issue: as soon as I run ros2 bag record, the robot's AUTO mode engages, which interferes with the problematic scenario I need to record. Therefore, I could only manage to record a partial data set.

My Plea for Help:
I've included my partial bag file and log files below. I'm really stuck on this one. Has anyone encountered a similar issue before? Any hints on where I should look or how to systematically debug this would be a lifesaver!
Thank you so, so much in advance for your time and expertise!

here is my log and bag:
outputoutdoor2025129.log
metadata.yaml
https://drive.google.com/file/d/1RQ2SzlYKhaY6Ld4UUATcEbLQ3FplMK6B/view?usp=sharing

[maxime-clem]

It is hard to identify the issue without more information. If you can, please share a rosbag recording that at least contains the vehicle status, localization, and control messages (the files you attached do not include any bag).

Based only on the screenshot, it looks like the control is fine (we see the predicted path that tries to go back to the lane), and there was no huge issue in the initial turns, so my best guess would be an issue with the vehicle or with the vehicle interface.

[LPARKOUR]

Thank you so much for taking the time to reply—I truly appreciate it! Sorry for the oversight; the link below now contains everything (logs + bags + maps). Thanks again for your help!

https://drive.google.com/drive/folders/1jYXDWY6-MhlGL51EX7H5au2C30kCeq_6?usp=sharing

[maxime-clem]

Thank you. The mcap file makes it easy to analyze the problem.

Based on the control steering command and the reported vehicle steering, it appears that the issue is with the vehicle not correctly following the command. This issue appears in the first turn as well but is less pronounced.
I believe the issue can be fixed by setting proper steering rate limits in the vehicle model of the mpc.param.yaml.

[LPARKOUR]

No, no — I’m the one who should thank you! Thank you so much, really!
All right, I’ll keep digging along the lines you suggested. Thanks again!