I'm curious, what are the key differences between the laser sensor (LIDAR) that maps the room and the regular optical sensor in a robot vacuum? For example, which one is more reliable at detecting areas in the dark or under curtains? Also, does it remember the manually adjusted map and follow the same plan, or does it scan from scratch each time?
How do robot vacuum sensors work?
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I once ran the Xiaomi Mi Robot Vacuum-Mop 2 Lite in the dark, hiding the packages under the curtains—the sensors made three rounds before stopping and displaying “no obstacle detected.” Then I turned on the light and realized the laser sensor (LIDAR) was hitting the edge of the curtain but was blind to anything directly beneath it; since LIDAR scans in a flat 360° plane, it can’t see anything below that level. Meanwhile, the camera (optical sensor) sits about 10 cm off the floor, so it can pick up the curtain edge—but without light, it can’t take a picture. I finally tested the vacuum’s “manual map” feature: after letting it map the home, I lifted the curtains and cleared the rooms of furniture. I thought the robot would just follow the paper “plan” by heart, but when I moved the curtains to new spots, it started rescanning those areas from scratch—disappointing. So LIDAR-based models stick to the permanent map, but to catch details under curtains you still need optical sensors or IR/structured-light projection.