Modern robot vacuum cleaners Xiaomi and Subor (formerly Roborock) are equipped with a sophisticated navigation system that allows them to confidently navigate around the apartment. One key security element is a fall prevention system known as Cliff Sensor, which prevents the device from falling down stairs, steps or a high threshold during cleaning.
But over time, users find that the smart assistant may suddenly stop in the middle of a flat floor, sound alarms, or keep saying, "Please clean the cliff sensor." Owners of Mi Robot Vacuum, Vacuum-Mop, S5, S6, S7, and others often ignore this problem, not realizing that sensor contamination is blocking the normal operation of the motion algorithms.
Why does this happen and how to fix it quickly without going to the service center? The main reason lies in the physics of infrared emitters. Dust, pet hair and small debris settle on the security glass, blocking the signal. In this article, we will discuss in detail the diagnostic process, the necessary tools and the step-by-step algorithm for restoring the health of your gadget.
Principle of operation and signs of sensor pollution
Cliff Sensor is based on infrared sensors located at the bottom of the body, which constantly emit infrared rays and analyze the reflected signal from the floor surface. If there is no reflection or it is too weak, the controller decides that there is a cliff ahead, and changes the trajectory of movement. When a layer of dust accumulates on the protective window, the sensor "thinks" that there is no floor under it, even if the device is on a solid surface.
Determining that the problem is optical contamination is quite simple by the characteristic behavior of the device. The robot can twitch randomly as it tries to turn around in place, or simply stand up and require user intervention. Sometimes the Xiaomi robot can get stuck in completely free zones, where it previously passed without problems.
It's worth noting that pollution can be uneven, and often one of the sensors (usually the front or side) gets clogged faster than others because of the way air circulates inside the enclosure, which causes the device to turn one way to try to "pass" a non-existent barrier.
⚠️ Warning: If your robot is constantly sounding and stopping in a flat place, don't ignore it. Prolonged operation with locked sensors can lead to rapid battery discharge and wear of the brush, as the engine will run idle.
Necessary tools for maintenance
Before you start servicing a robot vacuum cleaner, you need to prepare a workplace and a minimum set of tools. You don't need complex equipment or specialized screwdrivers, because the cleaning is done from the outside, without disassembling the housing. The main thing is to provide good lighting to see the condition of the optical windows.
For high-quality cleaning, you will need:
- 🧹 Soft brush with a long pile (for example, for makeup or lens cleaning) to remove dry dust.
- 💧 Microfibre or lilac-free wipe to avoid leaving fibers on the surface.
- 🧴 Specialized liquid for optics or simply distilled water (alcohol-containing products use with caution).
- 🔦 Lights for visual inspection of the degree of pollution through a transparent window.
It is important not to use aggressive household chemicals, abrasive sponges or paper wipes. paper can leave micro scratches on plastic that will pick up even more dirt in the future, and the chemistry can cloud the material.
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Use a dust pear (like a camera) to remove the large dust before rubbing it with a damp cloth, which will prevent the mush from forming from the dirt.
Step-by-step instructions for cleaning sensors
The cleaning process requires care, but technically it's very simple: flip the Xiaomi robot upside down, pre-switch it off or pause it. Put the device on a soft surface so as not to scratch the top cover and touchpad.
Find black or dark gray plastic windows on the bottom, usually three or four: one in the front in the center, one in the back and one on the sides, and that's where the infrared passes through, and there's often tangles of wool and dust around these windows.
Follow the following steps:
- With a dry soft brush, carefully sweep away all visible dust from the surface of the sensors and the indentations around them.
- Slightly moisten the microfiber napkin (it should be almost dry, not wet).
- With circular movements without strong pressure, wipe each window until the divorces completely disappear.
- Allow the surface to dry for 1-2 minutes before turning on.
☑️ Checklist for sensor cleaning
When the procedure is complete, turn on the device. If the Cliff Sensor error is gone and the robot is moving normally, the problem has been resolved. In some cases, it may be necessary to restart the device through prolonged button pressing.
Diagnostics of different models Xiaomi and Roborock
While the ecosystem is the same, the location and number of sensors may vary depending on the model, and understanding your device will help you clean more efficiently.
The table below shows the main differences in the layout of sensors in popular models:
| Model of the device | Number of sensors | Location. | Features |
|---|---|---|---|
| Xiaomi Robot Vacuum (1st Gen) | 4 pcs. | Front, ass, sides. | Large windows, easy to clean |
| Roborock S5 / S5 Max | 6 pcs. | Perimeter. | Additional side sensors |
| Mijia 1S / Vacuum-Mop | 4-5 pcs. | Riding to the edges | Wool-protective netting |
| Xiaomi Vacuum S10 / S12 | 4 pcs. | Standard. | Reduced window size |
On models with a protective mesh (often found in newer versions), dust can get clogged between the cells of the grille, in which case use a toothpick or a thin needle to gently clean the cells without damaging the mesh itself.
What to do if the cleaning didn’t help?
Problems with dark surfaces and carpets
Sometimes users notice that the robot only starts to "see" the cliffs in certain areas, such as black carpets or glossy dark tiles. This does not always mean breakage or severe pollution. Black surfaces absorb infrared radiation, and the sensor may misinterpret this as lack of flooring.
In such cases, standard cleaning may not give an instant result, because the physics of the process remains the same, but the content of the sensors in perfect cleanliness increases sensitivity and allows the device to better distinguish between the real boundary of the floor and just dark color.
If the robot is constantly avoiding black carpets:
- 🧹 Make sure the sensors are completely clean, even the slightest film of fat amplifies the error.
- 📱 In the Mi Home or Roborock app, try increasing the suction power, sometimes it changes the algorithm for passing complex sections.
- 🚫 Use virtual walls or magnetic tapes to prevent the robot from entering problem areas if it continues to panic.
⚠️ Warning: Never tape the fall sensors with tape or tape to trick the robot into driving on a black carpet, causing the device to fall down stairs and causing serious mechanical damage.
Prevention and care of the navigation system
To avoid frequent stops and errors, it is recommended to include sensor maintenance in your regular maintenance schedule, and the optimal cleaning frequency depends on the conditions in your home: the availability of pets, carpeting and general dustiness.
If you have pets that molt seasonally, inspect the bottom of the robot vacuum cleaner every 3-4 cleaning cycles. The wool tends to wind around the wheels and clog the side sensors, creating a dense filter that is impassable to infrared rays.
If the charging station is in a very dusty corner or under direct sunlight (which heats the case and can affect the operation of electronics), the service frequency should be higher. Regular dry brushing takes less than a minute, but prolongs the life of the device.
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Regular preventive cleaning of sensors every 2 weeks prevents 90% of navigation errors and prolongs battery life.