Xiaomi's robot vacuum cleaners are complex devices packed with dozens of sensors that are responsible for navigation, obstacle detection and cleaning. But when a vacuum cleaner starts to behave strangely -- bumps into furniture, can't see a ladder, or rushes around the room randomly -- the first thought is, "Is there a sensor that's broken?" To understand what exactly went wrong, you need to know where the sensors are and what each of them is responsible for.
In this article, we will examine all types of sensors in popular Xiaomi Mi Robot, Dreame and Viomi models (including the current 2022-2026 series), show their exact coordinates on the case and explain how to check the health of everyone. You will learn why a vacuum cleaner can ignore black carpets, how it “sees” walls without a camera, and what to do if it stops responding to steps, and how to clean or replace the sensor without contacting the service.
1.The main types of sensors in Xiaomi robot vacuum cleaners
All Xiaomi vacuum cleaners are equipped with a set of sensors, which can be divided into 5 key groups:
- 📍 Navigation sensors - responsible for building a map of the room (lidar, gyroscope, odometry).
- 🚧 Obstacle sensors – prevent collisions with furniture and walls (infrared, ultrasonic, bumper).
- 🪜 Height sensors – protect against falling from stairs and rapids (infrared cliff sensors).
- 🧹 Cleaning sensors - monitor the operation of brushes, turbines and dust collectors (sensors of blockage, dust, air flow).
- 🔋 Service sensors – monitor battery status, temperature, charging (thermistors, power controllers).
The number and location of sensors depends on the model and generation of the vacuum cleaner. For example, the budget Mi Robot Vacuum-Mop 2 Lite is a minimum set, while the flagship DreameBot X30 Ultra or Xiaomi Mi Robot Vacuum-Mop 2 Pro have advanced lidars, cameras and even a few more. 3D-We're going to take each group in detail below.
Navigation sensors: lidar, gyroscope and odometry
This is the vacuum cleaner's brain, which is responsible for mapping the room and planning the route, and without it, the robot will move chaoticly, like the first models of 2016.
🔦 Lidar (laser rangefinder)
The most important sensor in modern vacuum cleaners: a rotating laser module scans the room 360° and creates an accurate map, located under a transparent plastic dome at the top of the body (usually in the center), in models Xiaomi Mi Robot 2 and the newer lidar is hidden under a removable cover that can be cleaned of dust.
- 📌 Where to look: upper part of the body, in the middle (see photo below).
- ⚠️ Signs of malfunction: The vacuum cleaner is driving around in a circle, not building a map, or the map in the app is displayed with distortions.
- 🛠️ What to do: wipe the dome with a soft cloth, check the rotation of the lidar (should be freely spinning).
🌀 Gyroscope and accelerometer
These sensors track the angular turns and acceleration of the vacuum cleaner, helping the lidar to correct the map, are located inside the main board (not visible from the outside), if the gyroscope breaks, the robot will swim to the side or incorrectly display its position on the map.
📏 Odometry sensors (wheel encoders)
Small optical or mechanical sensors on the wheel axes that count the speed and help calculate the distance traveled. In the DreameBot and Viomi V3 models, encoders are built into the motor wheel.
⚠️ Warning: If the vacuum cleaner starts to slip on smooth surfaces (laminate floor, tiles) or zigzags, check the cleanliness of the wheels and the operation of encoders. Dirt on the sensors can knock down the readings!
| Sensor. | Location. | Signs of breakdown | How to check |
|---|---|---|---|
| lidar | Upper dome (centre) | No map, chaotic movement | Wipe the dome, check the rotation. |
| gyroscope | Inside, on the main board. | The vacuum cleaner floats sideways | Only diagnostics in the service |
| Wheel encoders | On the axles | Improper route, slippage | Clean the wheels and axles |
3 Obstacle sensors: how a vacuum cleaner "sees" furniture and walls
To avoid crashing into the legs of the chair or scratching the plinth, Xiaomi vacuum cleaners use a combination of infrared (IR), ultrasonic and bumper sensors.
📶 Infrared sensors (IR sensors)
They're positioned around the perimeter of the front bumper (usually 4-6 pieces), they emit an invisible beam and they catch the reflected signal, and if the beam doesn't come back, then there's an obstacle ahead.
- 📍 Where to look: Under transparent plastic on the front panel (see photo).
- ⚠️ Signs of malfunction: vacuum cleaner collides with furniture or "does not see" large items.
- 🛠️ What to do: wipe the plastic with alcohol (dust blocks the IR ray).
🔊 Ultrasonic sensors
They're used in the DreameBot X30 and Viomi V3 Pro models to accurately measure the distance to objects, and they're placed on the sides of the body (2-3 on each side), and they work like sonar, they send out a sound wave and measure the reflection time.
🪵 Bumper sensors (micro switches)
Mechanical buttons inside the rubber bumper that are triggered by physical contact, and if the vacuum cleaner does crash into an obstacle, the bumper pushes it back and tells it to pull back.
⚠️ Warning: If the vacuum cleaner is constantly bouncing off walls for no apparent reason, check the sensitivity of the bumper in the application settings. In Mi Home models, this is the parameter Pressing the bumper (by default, "Average Pressing Force»).
Clean IR sensors from dust|Check bumper mounting|Test of ultrasonic sensors in manual mode|Update the firmware (if sensors are bugged after the update)-->
4. Cliff sensors: protection from falling down stairs
One of the most important sensors for safety, the infrared cliff sensors are located on the bottom of the body and constantly scan the surface under the vacuum cleaner. If the beam is not reflected (for example, over a step), the robot stops and turns around.
In most Xiaomi models, 4 cliff sensors are installed:
- 2 at the front (under the front bumper);
- 2 at the rear (closer to the wheels).
The DreameBot D10+ and later vacuum cleaners have added laser cliff sensors to more accurately detect edges.
- 📌 Where to look: below, under transparent plastic (see photo).
- ⚠️ Signs of malfunction: vacuum cleaner moves from the thresholds, does not see the stairs or, conversely, is "afraid" of dark carpets.
- 🛠️ What to do: wipe the sensors with a cotton swab dipped in alcohol, and if the problem persists, check the sensitivity settings in the app (Settings) → Security → Sensitivity of Cliff Sensors).
Why is a vacuum cleaner afraid of black carpets?
5 Cleaning sensors: brush, turbine and dust collector monitoring
This group of sensors is responsible for the quality of cleaning and prevents breakages due to blockages.
🌀 Side brush speed sensor
A small optical or hall sensor inside the sidebrush mechanism, monitors if the brush is rotating, and if the sensor detects a stop, the vacuum cleaner will give an error.
💨 Airflow sensor (in the turbine)
Controls suction force. If airflow falls (for example, due to a clogged filter or a full vacuum collector), the vacuum cleaner increases power or stops with an error.
🗑️ Dust collector filling sensor
Auto-empty models like the DreameBot X30 Ultra have an infrared or weight sensor that detects when a container is full, and budget models often don’t have this sensor, using a timer instead.
⚠️ Warning: If the vacuum cleaner suddenly loses suction power, but does not show errors, check the condition of the filter HEPA. A clogged filter can fool an airflow sensor, and the vacuum cleaner will work "idle».
6.Service sensors: battery, temperature and charging
These sensors monitor the “health” of the vacuum cleaner and prevent critical breakdowns.
🔋 Battery level sensor
The Battery Management System (BMS) monitors the battery voltage, current and temperature, and if the battery is discharged or overheated, the vacuum cleaner automatically returns to the docking station.
🌡️ Thermistors (temperature sensors)
They're on the main board, next to the battery and the turbine engine, if the temperature is above 60-70.°C, the vacuum cleaner shuts down with an overheating error.
⚡ Dock sensors
The charging station has an infrared beacon (for precise docking) and contact sensors (for correct connection).If the vacuum cleaner can't find the dock, check the cleanness of the IR window at the station.
💡
If the vacuum cleaner has stopped charging normally, wipe the contacts at the docking station and robot with a washing gum, which will remove the oxidation that often causes poor contact.
7. How to check the sensors yourself: step-by-step instructions
If the vacuum cleaner is acting strange, don't rush to bring it to the service.
- Visual inspection: Check the purity of all external sensors (lidar, IR, cliff sensors).
- Manual Test: In the Mi Home or Dreame app, turn on Joystick Management mode and watch how the vacuum cleaner reacts to obstacles.
- Error Check: In the Settings menu → Device status, see the list of recent errors.
- Resetting: If sensors are buggy after an upgrade, reset to factory (Settings → Reset).
For deep diagnostics, use the service menu (not available on all models) to log in:
1. Turn off the vacuum cleaner.
2. Press the Home and Spot Clean buttons for 5 seconds.
3. Turn on the vacuum cleaner without releasing the buttons.
4. After the beep release - you are in the service menu.In the service menu, you can test each sensor separately (for example, check the rotation of the lidar or the sensitivity of cliff sensors).
💡
If the vacuum cleaner doesn't work properly after cleaning the sensors, update the firmware through the app. In 80% of cases, the sensors' glitches are due to software errors, not hardware breakdowns.