SO-101 follower disconnects during teleoperation

[Verlyba]

Ticket Type

🐛 Bug Report (Something isn't working)

Environment & System Info

LeRobot version:
- LeRobot version: 0.4.4
- Platform: Linux-6.17.0-14-generic-x86_64-with-glibc2.42
- Python version: 3.10.18
- Huggingface Hub version: 0.35.3
- Datasets version: 4.1.1
- Numpy version: 2.2.6
- FFmpeg version: 7.1.1
- PyTorch version: 2.7.1+cu126
- Is PyTorch built with CUDA support?: True
- Cuda version: 12.6
- GPU model: NVIDIA GeForce RTX 4070

Python version: 3.10
OS: Ubuntu 22.04
Hardware: SO-101 robot arm (leader + follower)
Servos: Hiwonder HX-30HM, HX-10HM
Power supply: 12V 20A
Connection: USB serial (/dev/serial/by-id)

Description

I am experiencing persistent disconnections when using teleoperation with an SO-101 leader/follower setup.

The issue occurs even after:

• recalibrating both arms
• verifying motor IDs
• replacing the power supply
• checking wiring
• resetting calibration files

Initially the teleoperation would run for a few seconds and then crash with:

ConnectionError: Failed to sync read 'Present_Position'

After further debugging and recalibration attempts, the error now occurs during robot connection:

RuntimeError: FeetechMotorsBus motor check failed

Here is the full code error:

(lerobot) verlyba@verlyba-PC:~/robotics/lerobot$ lerobot-teleoperate \
  --robot.type=so101_follower \
  --robot.port=$FOLLOWER \
  --robot.id=F1 \
  --teleop.type=so101_leader \
  --teleop.port=$LEADER \
  --teleop.id=L1 \
  --robot.disable_torque_on_disconnect=False
INFO 2026-03-11 20:33:00 eoperate.py:207 {'display_compressed_images': False,
 'display_data': False,
 'display_ip': None,
 'display_port': None,
 'fps': 60,
 'robot': {'calibration_dir': None,
           'cameras': {},
           'disable_torque_on_disconnect': False,
           'id': 'F1',
           'max_relative_target': None,
           'port': '/dev/serial/by-id/usb-1a86_USB_Single_Serial_5B3E119428-if00',
           'use_degrees': False},
 'teleop': {'calibration_dir': None,
            'id': 'L1',
            'port': '/dev/serial/by-id/usb-1a86_USB_Single_Serial_5B3E121827-if00',
            'use_degrees': False},
 'teleop_time_s': None}
INFO 2026-03-11 20:33:00 so_leader.py:79 L1 SOLeader connected.
INFO 2026-03-11 20:33:00 follower.py:106 F1 SOFollower connected.
Teleop loop time: 16.74ms (60 Hz)
INFO 2026-03-11 20:33:05 o_leader.py:156 L1 SOLeader disconnected.
Traceback (most recent call last):py:230 F1 SOFollower disconnected.
  File "/home/verlyba/miniconda3/envs/lerobot/bin/lerobot-teleoperate", line 6, in <module>
    sys.exit(main())
  File "/home/verlyba/robotics/lerobot/src/lerobot/scripts/lerobot_teleoperate.py", line 246, in main
    teleoperate()
  File "/home/verlyba/robotics/lerobot/src/lerobot/configs/parser.py", line 233, in wrapper_inner
    response = fn(cfg, *args, **kwargs)
  File "/home/verlyba/robotics/lerobot/src/lerobot/scripts/lerobot_teleoperate.py", line 224, in teleoperate
    teleop_loop(
  File "/home/verlyba/robotics/lerobot/src/lerobot/scripts/lerobot_teleoperate.py", line 163, in teleop_loop
    obs = robot.get_observation()
  File "/home/verlyba/robotics/lerobot/src/lerobot/utils/decorators.py", line 29, in wrapper
    return func(self, *args, **kwargs)
  File "/home/verlyba/robotics/lerobot/src/lerobot/robots/so_follower/so_follower.py", line 182, in get_observation
    obs_dict = self.bus.sync_read("Present_Position")
  File "/home/verlyba/robotics/lerobot/src/lerobot/utils/decorators.py", line 29, in wrapper
    return func(self, *args, **kwargs)
  File "/home/verlyba/robotics/lerobot/src/lerobot/motors/motors_bus.py", line 1146, in sync_read
    ids_values, _ = self._sync_read(
  File "/home/verlyba/robotics/lerobot/src/lerobot/motors/motors_bus.py", line 1178, in _sync_read
    raise ConnectionError(f"{err_msg} {self.packet_handler.getTxRxResult(comm)}")
ConnectionError: Failed to sync read 'Present_Position' on ids=[1, 2, 3, 4, 5, 6] after 1 tries. [TxRxResult] Incorrect status packet!

I tried checking the kernel for USB disconnections, but none appear.

Context & Reproduction

No response

Relevant logs or stack trace

Checklist

• I have searched existing tickets to ensure this isn't a duplicate.
• I am using the latest version of the main branch.
• I have verified this is not an environment-specific problem.

Additional Info / Workarounds

No response