After installing the M360, the buried wires were all removed.

We once provided a technical selection for a customer making courtyard robots. At that time, they were still using ultrasonic sensors and collision sensors for obstacle avoidance, relying on collisions to avoid tree roots and stones, and completely depending on buried underground boundary lines for lawn edges.

Later, the client wanted a version with no boundary, which means it doesn't require pre-buried wires and can be used immediately. We evaluated several radar models and finally chose TanTu Zhixing's M360. Now that the machine has been running for about a year, let's talk about the actual experience.

Why no longer use buried lines

The advantage of the buried wire solution is its simplicity and reliability, but the disadvantages are also obvious—it is troublesome to install and has high maintenance costs. If the grass grows quickly, the wires can be easily covered and cut during mowing. Each time the wire is cut, the lawn has to be dug up to reconnect it, leading to a high rate of customer complaints.

Without buried lines, the robot needs to "know" where the lawn's boundaries are, where there are trees, flower beds, and steps. This requires a perception solution.

We had previously looked at pure visual solutions and ultrasonic solutions. The pure visual solution works well when there is good light, but the shadow changes on the grass are too frequent, leading to a significant difference in recognition effectiveness between morning and evening. Ultrasonic sensors can only be used for short-range obstacle avoidance, with a limited perception range.

In the end, we chose a 3D LiDAR solution, specifically the M360 model. The core reason for choosing it is one: IP67.

IP67 is a necessity, not a luxury

Mowing robots operate in an outdoor lawn environment. They need to mow in both sunny and rainy weather—the grass doesn't stop growing because of rain.

We had previously tested a radar without a sealed protective cover. It worked fine in sunny weather, but after two rainfalls, the quality of the point cloud significantly decreased. Upon inspection, there was a layer of condensation on the lens, which cleared up for a while after cleaning, but it fogged up again a few days later. Later, we found that the sealing was not done properly, and moisture slowly seeped in.

The M360 comes with IP67 protection from the factory, meaning it is completely dustproof and will not be damaged by short-term immersion in water. We have tested it for a year, enduring summer heavy rain, autumn heavy rain, and winter freezing rain, and the radar itself has not had any issues. On several occasions, the machine continued to mow outside during heavy rain, and after the rain stopped, the radar surface had water droplets, which were simply wiped dry with a cloth, and the point cloud data was normal.

This is the first priority for us in choosing radar for lawn mower robots. No matter how strong the function is, if it keeps failing every few days, it's better not to use it.

The 5cm blind zone solves the problem of trimming grass along edges.

Mowing robots have a very practical requirement: they must mow right up to the edge of the lawn without leaving a strip of uncut grass.

This requires the radar to detect obstacles very close. The blind zone of traditional mechanical radar is generally 30~50cm, meaning it cannot see objects within 30cm. If there is a row of low shrubs on the edge of the lawn, and the height of the shrubs is lower than the radar installation position, the radar may not detect the roots of the shrubs within the 30cm blind zone, and the robot may collide with them directly.

The blind zone of the M360 is 5cm, which is the biggest difference between it and other radar of the same level. A 5cm blind zone means that the robot can basically sense obstacles "face-to-face." It can react in time when trimming grass along flower beds, walking along walls, or encountering small decorations.

Actual effect: After using the M360, the coverage of the lawn edges has increased from about 85% to over 95%. The previously occasionally uncut edges that required manual mowing are now basically covered.

There's a detail: In the mowing scenario, a 5cm blind zone is actually more important than the distance measurement. The working radius of a lawn mower robot usually does not exceed 50m (the size of a typical courtyard), so the difference between 70m and 50m measurement is almost imperceptible here. However, the difference in blind zones of 5cm and 10cm (MID-360) can be felt significantly during edge operations – for every additional 5cm of blind zone, an additional 5cm of edge is not mowed.

The benefits of a 70° vertical field of view

The radar of a mowing robot is usually mounted on the top of the machine, scanning in all directions. At this time, the vertical field of view determines how high a range it can "see."

The vertical field of view of the M360 is 70° (-10°~+60°), which is 11° wider than the MID-360's 59°. Do not underestimate these 11°.

There are some things in the courtyard that the radar can't see directly in front but can scan from above. For example, low-hanging branches, hanging vines, clotheslines, and crossbeams of flower racks. A vertical field of view of 59° may not scan the highest layer in these scenarios, but 70° can cover more.

There's another scenario: If a lawn mower robot needs to come down from a step (some courtyards have differences in height), a larger vertical field of view can detect the edge of the step earlier, avoiding a direct fall.

It can run without RTK

Many mowing robot solutions rely on RTK positioning, which is determined by satellite signals to locate the robot's precise position. RTK works well in open areas, but there are often trees and buildings in courtyards that can block the signal, making it easy to lose. Once the signal is lost, the robot doesn't know where it is.

The M360 solution does not require RTK. It relies on LiDAR for SLAM mapping and positioning and can determine its own location. This is particularly friendly for courtyard scenes – as long as the radar can see surrounding objects, it can be positioned, regardless of how dense the trees are or how tall the houses are.

From a cost perspective, eliminating the RTK base station and module can also save a lot of money. A set of RTK equipment costs several hundred to over a thousand yuan, which is not a small amount for consumer-grade lawnmower robots.

Multiple machines operating simultaneously

Some large lawns require two or three lawn mowers to work simultaneously. In such cases, if the radar lacks anti-interference capability, the laser signals of several machines may interfere with each other, and it is unclear whether the signals scanned are their own or others'.

The M360 has an active anti-interference design so that multiple machines working simultaneously will not interfere with each other. We have tested three machines cutting grass on a 2000 square meter lawn at the same time, and there were no cases of positioning deviation or obstacle avoidance misjudgment.

Potholes and stones

The most annoying things on a lawn are holes and stones. Holes may not be very deep, but they are traps for lawn mowers – the cutting disk can be damaged when hitting a hole, and it is even more direct when hitting a stone, leading to blade damage.

The M360 can scan the undulations of the lawn surface during mapping. We have added a layer of terrain analysis in our algorithm to identify depressions and elevations during the mapping phase, marking them as "attention areas." The lawnmower automatically slows down and avoids large stones when passing through these areas.

This feature is particularly practical for the clients. In their previous after-sales complaints, blade damage accounted for a large proportion, mostly caused by stones. After using the M360, the complaints about stones damaging the blades have significantly decreased.

Power consumption and battery life

The M360 consumes only 4.5W, which is low for a lawnmower. The battery capacity of a lawnmower is generally between 5000~10000mAh, and the motor itself consumes most of the power, so the radar's 4.5W is a small fraction. Our actual test shows that after adding the M360, the battery life is reduced by about 10~15 minutes (from the original 90 minutes to about 75 minutes), which has little impact on actual use.

If a radar with higher power consumption is used, the battery life will be significantly reduced, possibly requiring a larger battery capacity, which would increase costs and weight.

The current state

Currently, the clients' lawn mower robots have been mass-produced using the M360 solution, mainly sold in overseas markets. It's almost a year since the first batch of shipments, and there have been no radar-related faults reported in the after-sales feedback.

The client summed it up by saying that the biggest change after switching to the M360 is the installation experience—the previous process required technicians to come on-site to bury wires and tune the machine, which took half a day to complete one unit. Now, it takes just 15 minutes to unpack, turn on the machine, and let it run a circle to build the map. This experience gap is significant for overseas customers, as the cost of sending technicians on-site is too high.

The above is based on actual project testing; the M360 parameters are to be taken as the official information from TanTu ZhiXing.