Unitree L2 shows duplicated walls and Z-axis oscillation during mapping #27
Description
Description
While using Unitree 4D LiDAR L2 for mapping, static structures such as walls appear duplicated in the map.
The LiDAR seems to oscillate along the Z-axis, causing the same wall to appear as two parallel surfaces.
Expected Behavior
- Static walls should appear as a single surface
- Consecutive scans should be consistent
- Mapping should remain stable
Actual Behavior
- Walls appear duplicated (two parallel walls, ~5–20 cm apart)
- In consecutive scans, the same wall is sometimes detected at significantly different distances
- This results in repeated points, scan mismatches, and unstable SLAM
- Raw point cloud looks clean (not noisy)
Observations
- Issue becomes more visible when the robot is moving
- Looks systematic rather than random noise
- Possibly related to timestamp synchronization, deskew, IMU integration, or extrinsic calibration
Reproduction Steps
- Mount L2 on a mobile robot
- Start mapping in an indoor environment with flat walls
- Move the robot forward
- Observe duplicated walls and Z-axis oscillation in the map
Additional Information
- We can provide video recordings demonstrating the issue
- ROS2 rosbag recordings are also available
- Issue has been reported to Unitree via official support form
