Xiaomi’s robotic assistants have become an integral part of the modern smart home, ensuring cleanliness without human intervention. However, even the most advanced models, such as the Xiaomi Vacuum Mop 2 or Roborock S7, eventually begin to fail. Often the cause is not a breakdown of the engine, but a banal contamination of optical sensors. Dust, animal hair and small debris can close the lenses, causing the device to lose orientation or completely stop cleaning.
Owners often experience a device that rushes randomly around a room, gets stuck in a flat place, or makes alarm bells to signal a fall. Sensors are your gadget's eyes, and if they're contaminated, it becomes blind. Regular maintenance of optics allows you to extend the life of the equipment and avoid costly repairs in the service center. In this article, we'll take a closer look at which sensors need attention and how to clean them safely.
Before disassembling, it is important to understand that different models may have different sensor configurations: some devices have single holes, others have entire clusters of lenses under transparent plastic. It is important to act carefully so as not to damage fragile elements or damage the tightness of the body. The use of aggressive chemistry or abrasive materials when cleaning optical lenses is strictly prohibited, as this will lead to their clouding.
Diagnosing navigation and sensor problems
The first step before physical cleaning should always be diagnostics. Understanding which sensor is floundering will help focus your efforts and avoid disassembling the unnecessary. Xiaomi and Roborock are equipped with a self-diagnostic system that gives out error codes through the Mi Home app or voice messages. If a robot reports a problem with a drop sensor or gets stuck on a flat floor, this is a direct signal to check the optics.
And if you look at the behavior of the device when it's running, if it's constantly hitting obstacles that you've been walking around, or if it's squandering on imaginary walls, then the lidar or side sensors are not working properly, and if you're looking at the top laser window, it's also worth checking if it's dusted, which is often the case after a dry cleaning, sometimes the problem is solved by simply wiping the outside, but in advanced cases, you'll need a deeper approach.
To accurately detect a malfunction, you can use the in-app diagnostic mode if your model supports this feature. It often displays the status of each sensor in real time. If you see a particular sensor not responding to obstacles or showing an incorrect distance to the floor, cleaning it becomes a priority. Don't ignore these signals, because prolonged work with contaminated sensors can lead to overheating of the processor due to constant calculations of erroneous data.
Tools and workplace preparation required
You can't clean properly without the right tools. You can't use the first rag you find or the poor cotton swabs that can leave the villi inside the machinery. You need a kit that can safely remove the contaminants without the risk of damaging the electronics. Workplace preparation is also important: choose a well-lit table with a flat surface.
Here is a list of what you will need to do the procedure:
- 🧹 Microfibre without pile – perfect for wiping lenses without scratches.
- 💧 Distilled water or special spray for optics – ordinary tap water can leave salt plaque.
- 🦇 Pear for purging or a can of compressed air - to remove dust from hard-to-reach places.
- 🪄 Plastic blade or mediator - for careful opening of the latch of the body.
- 🔦 Lantern – to better see the pollution in the depths of the holes.
It is important to turn the device off from charging and completely turn it off before work. If the model has a removable battery, it is better to remove it to eliminate the risk of short circuit in case of accidental contact of tools with the board. The work surface is recommended to cover with a soft cloth so as not to scratch the body of the robot and not to lose small screws if you need to disassemble. Also keep a container for folding fasteners on hand.
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Use only distilled water to wet wipes, as mineral salts from ordinary water after drying form a microscopic crust on the lenses, impairing their transparency.
Cleaning of external sensors and drop sensors
The drop sensors are located at the bottom of the body, usually around the perimeter, and their job is to scan the surface under the robot and prevent it from falling off stairs or rapids, and they are the ones that are most often clogged with dust because they are closest to the floor. If the robot starts to think there's a chasm ahead and goes back in a flat place, the problem is almost certainly in them.
To clean, turn the robot vacuum cleaner upside down. You'll see some dark windows -- these are infrared emitters and receivers. Gently wipe them with a dry microfiber. If the contamination is severe, slightly moisten the fabric with distilled water or alcohol, but don't pour the liquid directly onto the sensor. The movements should be soft, circular, without much pressure. After wet cleaning, be sure to let the surface dry for 5-10 minutes.
Often, the sensors will be filled with a dense lump of dust that you can't remove with a dry cloth. In this case, use a cotton swab slightly soaked in the cleaning product. Walk carefully on the surface of the lens to remove plaque. Don't use sharp objects like needles or toothpicks, as you can scratch the plastic, which will cause the beam to disperse and false positives. After cleaning, blow the pear holes to remove the remains of the pile.
☑️ Cleaning the lower sensors
Lidar and upper navigation sensors
Laser-navigated models (LDSs) have a tower-like protrusion on the top lid, and a laser rangefinder rotates inside it, and it maps the space, and there's a narrow, transparent window on the side of the tower, and that's where the laser scans the space, and contamination of this window is one of the most common reasons why the robot can't build a map or loses its location.
Wipe the outside of the laser window with a soft cloth. If you notice that dust has accumulated under the transparent plastic, carefully remove the top lid of the tower. In most Xiaomi and Roborock models, it is held on magnets or light latches. Stripping the edge with a plastic shovel, removing the ring and removing the dust with a dry brush or pear. Inside, there can be surprisingly much fine debris that has interfered with the device for years.
In addition to the main lidar, the body can have additional obstacle sensors (usually in the front) that look like small black dots, and they also need to be kept clean, otherwise the robot will constantly bump into the legs of chairs or walls. Use the same method: dry wipe followed by wet if necessary. Make sure that the sensors do not leave any villi from the fabric.
What if the laser module stopped rotating?
Wheel sensors and side sensors
Robot vacuum wheels are also equipped with optical or mechanical sensors that detect rotational speed and contact with the surface. The cracks of the wheel modules often stuff hair and wool, which block not only rotation, but also sensors, which can cause the error "Wheel hung" or "Robot inclined."
Remove the side brush and inspect the area around the wheels. Use tweezers or a thin screwdriver to pull the coiled hair out of the axles. To clean the optical sensors inside the wheel arches (if your model has one), use a cotton swab. It is important to remove all the pile, as it can get into the machinery and cause jamming. After cleaning, check if the wheels are free when pressed with your hand.
The side sensors that make the way around obstacles are often located on the bumper or on the sides of the body, and they can be hidden under decorative elements. Rub these areas carefully, because even a thin layer of fat from the hands or sticky dust can distort the readings. If the robot stopped walking around obstacles normally on one side, check this sector.
| Type of sensor | Location. | Symptoms of pollution | Cleaning method |
|---|---|---|---|
| Cliff Sensor (falls) | Bottom panel. | The robot is backing up or falling down. | Microfiber wipe |
| LDS (Lidar) | Upper Tower | He doesn't build a map, he loses it. | Removal of the lid, purging |
| Wall Sensor (walls) | Right side | He doesn't go right along the walls. | Wet wipe |
| Wheel Encoder | Inside the wheels | Motion error, chaos | Tweezers hair removal |
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Regular cleaning of the wheel sensors prevents the error of "lifted above the ground" as the contact sensors stop sticking in the dust.
Frequent maintenance errors and safety
When you self-maintain the machine, it's easy to make mistakes that can cost more than just replacing the filter. One of the most common mistakes is using too much moisture. The fluid can leak into the housing and oxidize the contacts of the control board. Always apply the cleaning product to the fabric, not the robot itself.
Another mistake is the use of aggressive solvents, such as acetone or Kalosha gasoline, which can dissolve the plastic of the case or make transparent sensor lenses cloudy and opaque forever. Use only water, isopropyl alcohol or special devices for screens and optics. Also, do not blow on the sensors with your mouth, since saliva can get on the lenses and dry with hard-to-remove spots.
⚠️ Warning: Never turn on the robot vacuum cleaner immediately after wet cleaning. Let it stand at room temperature at least 15-20 It can take a minute to evaporate all the moisture, and it can short circuit the wet device.
Another important thing is that you don't ignore the mechanical damage. If you notice a crack in the lens of the drop sensor, a simple cleaning won't help. The light will not dissipate correctly and the robot will work incorrectly. In such cases, you need to replace the part. Also monitor the condition of the rubber seals around the sensors, if they are designed; their damage violates the dust protection.
⚠️ Note: When cleaning the laser module (LDS) Don't rotate the head manually with force. It has a thin axis that can bend or break easily when you're not handling it carefully.
Checking the performance after cleaning
Once all the procedures are complete and the device is dry, you need to check its operation. Assemble the robot in reverse order, making sure that all the covers fall into place with a characteristic click. Turn on the device and start a short cleaning in Local mode or just let it drive around the room. Pay attention to how it responds to obstacles and thresholds.
Check the Mi Home app. If there have been errors before, they should disappear. Build a new room map if necessary. The robot should move confidently, without abrupt stops or turns from scratch. Test at the edge of the threshold or step (exercise caution, hold the device) to make sure the drop sensors are working correctly and stop movement in time.
If the problems persist, it may not be the only cause, or it may require a deeper diagnosis of electronics. However, 90% of the time, a thorough optics cleaning restores the robot to its previous efficiency. Regularly doing this prophylaxis once every 1-2 months will allow your smart assistant to serve you faithfully for years without failure.