Xiaomi’s robotic vacuum cleaners and their sub-brands, such as Roborock or Mijia, have become an integral part of the modern smart home, and their effectiveness depends on the accuracy of sensors that scan the room and prevent falls. Over time, even perfectly clean apartments with optics accumulate a thin layer of dust, invisible to the eye, but critical to the work of the laser.
If your gadget has started to rush around the room randomly, get stuck in the flat, or, worse, fall from the doorsteps, the problem is often the pollution of sensor systems. Ignoring this signal leads to incorrect mapping and reduced cleaning quality. In this article, we will discuss how to safely conduct maintenance of optics.
And you have to understand that navigation sensors are optical devices, not just plastic windows, that rough cleaning or aggressive chemicals can permanently disable them, and that the right approach will extend the life of the device for years and make it work perfectly.
Diagnosing pollution: when it's time to clean
The first signs that optical sensors need attention are errors in the logic of movement. The robot may stubbornly ignore obstacles or, conversely, panick from imaginary walls. Often the device emits audible signals or voice messages about getting stuck, although there are no obstacles in the way.
If Xiaomi refuses to move forward on a dark carpet or constantly stops at the edge of a rug where there is no drop, the cliff sensors are likely blocked. This is a critical safety feature that must correctly function.
Check the app on your smartphone. If the map is distorted, blind spots appear, or the robot loses its position in the middle of the room, this is a sure sign of problems with the lidar or side sensors. Visual inspection is also mandatory: even a slight haze on the black glass of the sensor requires immediate intervention.
⚠️ Warning: If the robot starts falling down sills or stairs, immediately stop using it automatically.This indicates a complete failure of the anti-collision system, which can lead to expensive repairs.
Timely diagnosis avoids more serious engine failures that can overheat due to constant attempts to overcome non-existent obstacles, and regular checks of sensors should become a habit, especially in homes with pets or high dust levels.
Preparation for maintenance: tools and security
Before you start any manipulation, you have to completely de-energize the device, not just put it on the base, but physically turn off the power or wait for the complete discharge if the design allows, and you can't work with electrically energized batteries, even if you're talking about low-voltage batteries.
You'll need a minimal toolkit that you'll find in every home, and the rule is that there's no pile or abrasive particles, and using regular paper wipes or rough fabrics can leave microscopic scratches on the lenses that will scatter the laser beam.
- 🧹 High quality microfiber – ideal for wiping optics without divorces.
- 💧 Distilled water or special spray for screens – ordinary tap water may contain salts.
- 🖌️ Soft brush for drawing or antistatic brush – to remove dust from hard-to-reach places.
- 👂 Cotton swabs – necessary for careful cleaning of the depressions around the sensors.
It is strictly forbidden to use alcohol-containing solvents, acetone or ammonia window washing agents, which can destroy the anti-reflective coating of the lenses or make the plastic of the case cloudy. Isopropyl alcohol is permissible only in extreme cases and in low concentrations, but it is better to limit yourself to water.
☑️ Preparation for cleaning
Lidar Cleansing (LDS): The Heart of Navigation
The most important element in laser navigation models is the block. LDS (The Laser Distance Sensor, which is located in a characteristic cylinder on the top panel, is the one that rotates and builds. 3D-Contamination of the protective window or the laser emitter itself results in "noise" on the map.
Access to the sensor often requires removing the top cover of the dust bin. In some models, such as the Roborock S5 or Xiaomi Vacuum Mop 2, the lidar window is under a transparent cap. Gently wipe the surface with a soft cloth in circular motions without pressing hard.
If you notice dust inside the rotating mechanism itself, you'll need a deeper cleaning. Remove the turret lid (usually held on latches or screws under the sticker). Blow the mechanism with compressed air or carefully remove contamination with a dry brush. The rotating part can be slightly wiped with microfiber, but be careful with the plume wires.
⚠️ Warning: Never attempt to disassemble the laser module itself inside the turret. This is a calibrated device, and a violation of its geometry will make it impossible to build a map.
Once cleaned, assemble the device and start building the map again, and if the laser rangefinder is working correctly, the robot should move in straight lines, methodically cleaning sector by sector, rather than scattering around randomly.
Maintenance of elevation sensors (Cliff Sensors)
The elevation sensors, or "cliff sensors," are located at the bottom of the body, usually around the perimeter, and their job is to read the reflection of the signal from the floor, and if the floor is dark or the sensor has stuck dirt, the robot thinks there's a cliff ahead, and stops.
Turn over the vacuum cleaner and look at the black windows of the sensors. Often they are covered with a layer of dust or wool that looks like gray plaque. Wipe them with a wet (not wet!) microfiber wipe. Make sure the fabric does not leave any villi that can stick to the occasionally sticky plastic.
And you pay particular attention to carpet-mode models, and they can have an additional optical sensor to recognize carpets, and the contamination causes the robot to either go on the carpet when it shouldn't, or to go around the clean floor.
Check the sensors by holding your hand to the bottom of the robot on (in cleaning mode). In some models, when the sensor is triggered, the nature of the motor sound changes or the indicator lights up. If there is no reaction even after cleaning, you may need to change the module.
Cleaning of wheel encoders and side sensors
The side obstacle sensors are often located on the bumper or in special recesses on the sides of the body, which prevent collisions with furniture at low speed, and dirt accumulates most quickly due to contact with the plinths and legs of chairs.
Wheel encoders are optical sensors that read the rotation of the wheels. There's a risk disk on the axis of the wheel that spins in the optocouple, and if dust and wool are stuffed in there, the robot will lose orientation in space and spin in place, reporting a wheel error.
- 🔍 Remove the side brush and inspect the space underneath it - there is often a buildup of debris.
- 🌀 Carefully clean the niche of the main wheel, removing the wound wool from the axis.
- 👁️ Wipe the optical pair of encoder with a dry cotton swab, without using the liquid inside the mechanism.
To clean the side IR sensors, use a dry brush to dust out the recesses, then wipe the lens itself. If the bumper is mechanical (pressed), check if dirt is stuck in the motor, which can cause false positives.
What if the sensor doesn’t work after cleaning?
Table of frequency of sensor maintenance
Cleaning is regular depending on the operating conditions, and in an apartment with a molting dog, you will have to service optics more often than in a studio of one person.
| Sensor type | Conditions: Apartment without animals | Conditions: House with animals | Conditions: Dust/Repair |
|---|---|---|---|
| Lidar (LDS) | Every 2-3 months | Once a month | Once every 2 weeks |
| Height sensors | Once a month | Once every 2 weeks | Weekly |
| Side sensors | Every 2 months | Once a month | Once every 2 weeks |
| Encoders of wheels | Every 6 months | Once in 3 months | Once a month |
Keeping this schedule in place will keep the navigation system in perfect condition, and remember that prevention is always cheaper and easier than repairing or replacing expensive modules.
Typical errors and program resets
Sometimes even perfectly clean sensors don't work properly because of software failures, and the cache of the card can contain errors that prevent the robot from navigating, and in such cases, resetting the map and creating a new one helps.
A common mistake is to use glossy floor polishes immediately after cleaning the robot. Chemical traces can settle on the lower optics, creating a rainbow film that distorts the sensor readings. Let the floor dry before starting.
⚠️ Warning: Do not use a vacuum cleaner to clean the robot vacuum cleaner itself at full capacity.The flow of air can drive fine dust deeper into electronic components or damage the thin membranes of microphones.
If the problem persists after a physical clean, try resetting the device to factory settings through a button combination or app, which will delete all temporary files and potentially corrupt navigation data.
💡
Dry the sensors immediately after each wet cleaning if your robot supports the wash function.The residue of detergent on the height sensors can lead to false cliff signals.
Frequently Asked Questions (FAQ)
Can I wash the sensors with water under the tap?
Why does a robot see obstacles where there are none?
How often should you change your sensors in Xiaomi?
Does the color of the floor affect the sensors?
💡
Regular dry cleaning of optics with microfiber is the most effective way to keep the robot vacuum cleaner’s navigation accurate for many years.