Xiaomi's robot vacuum cleaners are not just smart mops, but complex devices with a dozen sensors that provide navigation, avoidance of obstacles and even recognition of coating types. If your robot vacuum cleaner starts beating against furniture, or not navigating space or ignoring stairs, the problem is probably one of the sensors. But how do you find them? Where are they hidden under the case, and can you check them yourself?
In this article, we will discuss all types of sensors used in Xiaomi Mi Robot, Dreame and Viomi models (including the popular Mi Robot Vacuum-Mop 2 Pro, Dreame D9, Viomi V3). You will learn their exact location, operating principles and malfunction signs. And for those who are planning repairs, we will give unique disassembly schemes with the indication of the blind spots of sensors, which are often missed even in service centers.
1.The main types of sensors in Xiaomi robot vacuum cleaners
Modern robot vacuum cleaners Xiaomi equipped with 7-12 sensors (depending on the model), which are divided into three groups:
- 🧭 Navigation – responsible for map construction and orientation in space (gyroscope, accelerometer, laser/optical sensor).
- 🚧 Anti-collision – prevent impacts on furniture and walls (infrared, ultrasonic, bumper).
- 🔋 Service - monitor the state of the vacuum cleaner (sensors of dust, charge, overheating, fall).
For example, Xiaomi Mi Robot Vacuum-Mop 2 Pro has a laser rangefinder (LDS) for scanning the room, while budget models (for example, Mi Robot Vacuum 1C) use optical navigation with the camera.
2.Where is the laser sensor (LDS) and how does it work
Laser rangefinder (LDS — Laser Distance Sensor is the robot’s eyes that scan the 360 room.° And they build a map. In Xiaomi models, it's placed under a rotating transparent lid on the top panel (see photo below). ~5 revolutions per second, emitting laser beams.
🔍 How to check the performance LDS:
- Turn on the robot and put it on a flat surface.
- Start cleaning – if the lid is not rotating or spinning in jerks, the sensor is faulty.
- Illuminate a flashlight on the lid: in the dark should be visible red beam (if not - the laser module burned).
⚠️ Warning: Never block the rotation LDS If the robot makes a mistake Laser sensor is blocked (Error 10), check if any debris or hair has been lided.
What to do if the LDS does not work?
3. Infrared (IR) and ultrasonic sensors: where they are hidden
These sensors are responsible for detecting obstacles at a close distance (up to 10-15 cm).
- 🔴 IR sensors: around the bumper perimeter (front) — usually 4-6 pieces (2-3 on each side) — they look like little black dots.
- 🔊 Ultrasonic sensors: in models with support 3D-scanning (e.g. Dreame) D10 Plus) installed under the front panel.
Signs of malfunction: the robot beats the legs of chairs, does not see low obstacles (wires, rapids), or gets stuck in corners, often caused by contamination of sensors (dust, animal hair).
☑️ How to Clean IR Sensors
| Type of sensor | Location | Signs of breakdown | How to check |
|---|---|---|---|
| Laser (LDS) | Under the rotating top cover | Not building a map, Error 10 error | Visually (rotation, laser beam) |
| Infrared (IR) | On the edges of the bumper (4-6 pcs.) | He sees no obstacles, he fights against furniture. | Tester (chain vertebrating) |
| Ultrasonic. | Under the front panel (in premium models) | Ignoring low objects | Run the test in the service menu |
| Fall sensor | Under the bottom (4 pcs in the corners) | Falling down the stairs, Error 3 error | Blow under the sensor (should be triggered) |
4 Fall sensors: why the robot is not afraid of stairs
One of the most important sensors is the drop sensor, which prevents a robot from falling down stairs or high thresholds. Xiaomi models usually have 4 of them, located under the bottom at corners (see photo).
🛑 Error 3 means that one of the sensors is contaminated or faulty:
- Turn the robot over and find the sensors (they look like small windows with black glass).
- Blow under the sensor – if it is working, the robot must stop (as if it “saw” the abyss).
- Wipe the sensor glass with a dry wipe (do not use liquids!).
⚠️ Note: If Xiaomi robot suddenly starts ignoring stairs, don’t be in a hurry to change sensors. 60% of the time, the problem is solved by updating the firmware – in older versions of the software there was a bug with the calibration of sensors.
5. Dust and charge sensors: where they are and how to test them
These sensors are responsible for automatic adjustment of the suction power and monitoring the battery level:
- 🌪️ Dust Sensor: located inside the dust collector (in models with Smart Dust Detection function, for example, Dreame) D10 It measures the concentration of dust in the air and increases the power in case of severe pollution.
- 🔋 Charge sensor: It's on the motherboard next to the battery connector, and it monitors the voltage and temperature of the battery.
How to check the dust sensor:
- Turn on the robot and start cleaning.
- Bring some flour or talc to the suction hole.
- If the robot has not increased power (no increased noise was heard), the sensor is faulty.
💡
If Xiaomi's robot is rapidly discharged, check the contacts of the charge sensor. Often they oxidize due to moisture (for example, after wet cleaning), wipe them with a stripe or alcohol.
Gyroscope and accelerometer: Hidden Navigation Sensors
These sensors are not visible from the outside because they're soldered into the motherboard.
- 🧭 Gyroscope: determines the angle of the robot (so that it does not overturn on the carpet).
- ⚡ Accelerometer: Measures acceleration and helps calculate distance traveled.
🔧 Signs of failure: the robot moves zigzags, loses orientation after climbing the carpet or gives an Error 9 error (gyroscope malfunction), unfortunately, these sensors are not repaired, only replacement motherboard (~8 000–12 000 ₽).
💡
If Xiaomi robot after falling or hitting became "drunk" (spins on the spot, goes sideways), with a probability of 90% to blame the gyroscope. In this case, the repair is unprofitable - it is cheaper to buy a new vacuum cleaner.
7.How to disassemble Xiaomi robot vacuum cleaner to access sensors
If you decide to clean or replace the sensors yourself, follow this instruction (as exemplified by Mi Robot Vacuum-Mop 2 Pro):
- Disconnect the robot from the network and remove the battery (unscrew 4 screws on the bottom).
- Remove the top cover: put it on a plastic card around the perimeter (starting at the back).
- Disconnect the bumper and LDS plumes (remember their location!).
- To access the drop sensors, remove the bottom panel (unscrew 8 screws).
⚠️ Note: In the Dreame and Viomi models, the laser sensor calibration may be lost after disassembly. To restore it, after assembly, launch the robot in calibration mode (hold the Home button for 5 seconds).