Persistent Steering Offset on PiCar-X (Robot HAT V44, Pi 5) — Calibration Not Working

General
1

Hello SunFounder Team,

I’ve already sent an email to support@sunfounder.com regarding this, but I wanted to post here as well so it reaches your technical staff.

I’m facing a persistent steering calibration issue on my PiCar-X (for Raspberry Pi 5) using the Robot HAT V44. Even after following every documented step, the front-left wheel keeps grazing the chassis — the steering servo always turns hard right when zeroed.

Summary of what I’ve tried:

  • Pressed and held the Zero button (6 s) to reset MCU.

  • Ran 1.cali_servo_motor.py repeatedly and saved (space → y).

  • Swapped all three servos — every one behaves the same.

  • Verified correct wiring (S-V-G orientation).

  • Disabled and removed Ezblock to prevent interference.

  • Reinstalled the robot-hat and picar-x libraries in a clean virtual environment.

  • Swapped servo ports — the offset follows the port, not the servo.

It looks like the steering output on the HAT may have a stored offset or firmware calibration issue, since all other channels (pan/tilt, motors) behave normally.

Could your engineering team please review my email and advise?
I’d really appreciate a short video or Zoom session to show the behavior live — it would take only a few minutes to confirm if the Robot HAT V44 needs a firmware re-flash or replacement.

Setup details:

  • Raspberry Pi 5 (8 GB)

  • Robot HAT V44 (top speaker)

  • PiCar-X chassis kit (2025 purchase)

  • Raspberry Pi OS (Bookworm 64-bit)

Thank you for your time and help — I’ve put a lot of care into this build, and I’d love to resolve this steering offset properly.

Steering Servo Issues on PiCar-X with Pi 5
2

If I could please get someone to help me on a video call, that would be so wonderful, I have everything set up in front of my computer itself.

3

We recommend providing us with a video of the issue to help us analyze and resolve the problem for you.

If the video file is large, please upload it to your OneDrive, share the link with us, and grant us access permissions. This will allow us to assist you more effectively.

4

hi team, thank you so much for the guide you provided on email.

I was able to fix the servos once more after unplugging and rebuilding that part specifically.

I can still upload a video to show you how it moves so you can confirm if everything is okay?

5

Of course, we would be very glad for you to provide a video for our review.

If the video file is large, we recommend uploading it to OneDrive. Then, please share the link with us and grant us access permission. This will allow us to view the video and help you analyze the issue.