When the Xiaomi Robot Vacuum S40 is cleaning along the edge, it keeps a certain distance from the wall, and it is normal for occasional collisions.
For your reference, here is more information about bumping walls when cleaning along edges:
1. The robot vacuum uses sensors to detect nearby walls and edges. Occasionally, making light contact allows it to adjust its path more precisely, improving cleaning coverage along borders and corners;
2. On reflective or dark-colored walls, infrared or proximity sensors can experience reduced accuracy. This will lead to slightly more frequent wall contact;
3. During initial mapping or after moving the robot vacuum to a new environment, it could temporarily collide more often as it learns the layout.