Having worked on unmanned forklifts for over three years, from the initial 2D single-line radar navigation to the full 3D perception solution now, I've changed several rounds of sensors in the process. Starting last year, I began testing the TanTu ZhiXing M360, while also having the Livox MID-360 on hand for comparison. After half a year of operation, I've recorded some actual feelings.
The differences between the unmanned forklift and the ordinary AGV
To be clear, although both unmanned forklifts and warehouse AGVs are called "unmanned transporters," their working modes differ greatly:
- There is an up and down movement. The radar installation height changes when the forks are raised and lowered, and the point cloud coordinate system moves with it.
- The load capacity varies greatly. It weighs 2 tons when empty and 5 tons when full, with a different center of gravity, so the obstacle avoidance response needs to be adjusted accordingly.
- It needs to be parked accurately. The spacing error between the forklift and the shelf when loading cannot exceed 2~3cm, otherwise it cannot be inserted.
- Both indoor and outdoor operations are required. Some warehouse exit points are outdoors, and the forklift has to cross back and forth.
- Slow working speed but high accuracy requirements. Generally 0.5~1.5m/s, but the perception accuracy of the surrounding environment is more stringent than that of high-speed AGVs.
These characteristics determine that the requirements for radar on the unmanned forklift are not completely the same as those for the ordinary AGV.
Why switch from 2D to 3D
We have been using 2D single-line radar for navigation, which works well for obstacle avoidance within the plane, but it has a fatal flaw: 2D radar scans a horizontal plane, and objects above the shelves are not visible.
Once, the forklift was reversing in the aisle, and the 2D radar confirmed that there were no obstacles behind. However, a cardboard box was sticking out from the highest shelf, just above the 2D scan plane. When the forklift tilted back, it knocked the box down. Fortunately, no one was injured.
Since then, we have decided to switch to 3D radar. 3D radar can cover the vertical space, scanning overhanging objects on shelves, suspended pipelines, and unevenly stacked goods.
Performance of M360 vs. MID-360 on forklifts.
Both radars were installed on the forklift roof at a height of 2.2m, inclined downward by 15°. They were tested for half a month for comparison.
Near-range blind zone
The spacing between the forklift and the shelves is generally controlled at 20~30cm, and it is necessary to confirm that there are no obstacles in the forklift area before inserting the forks. The obstacles in this area may be deformed crossbeams at the bottom of the tray, packaging straps on the ground, or residues left by the previous forklift.
The 5cm near-field blind zone of the M360 is clearly advantageous in this scenario. Our tests have shown that the detection rate of M360 for small obstacles below 10cm in the fork area is about 95%, while for the MID-360 it is about 80%. The main difference is in the 5~10cm range—the 10cm blind zone of the MID-360 just covers this section.
For unmanned forklifts, the forklift loading accuracy requires 2~3cm. If the radar cannot see anything within a range of 5~10cm, there is a potential safety hazard. A 5cm blind zone is a relatively comfortable lower limit.
Power consumption and power supply
Unmanned forklifts use 48V or 80V battery packs, with the whole vehicle power consumption at the level of 3~5kW. The difference of a few watts in a single radar has little impact on the range.
But there are considerations in the power supply design. Our forklift uses a 48V main battery, with a DC-DC converter stepping down to 24V to power the sensor. The M360 has a generous input range of 12~32V, while the MID-360's 9~27V is still usable but with less margin. The forklift experiences significant voltage fluctuations during rapid acceleration and deceleration, and insufficient margin occasionally triggers low-voltage protection.
We suffered a loss here—the forklift using the MID-360 restarted the radar twice during heavy load emergency braking. Later, a voltage stabilizer module was added to solve the problem. The M360 forklift did not have this issue.
IP rating
Both are marked with IP67. Forklifts operate in warehouses where dust is not uncommon, and they occasionally pass through damp areas. IP67 is sufficient for forklifts. However, we noticed that the IP67 of the MID-360 was only added in the latest version, and the older batches may not be IP67. Confirm the batch when purchasing.
Non-repetitive scanning + Low-speed accumulation
The forklift moves slowly in the shelves channel, and sometimes it has to stop for alignment. Both the M360 and MID-360 support non-repetitive scanning, and the angular resolution will continuously improve in a stationary state.
Actual Effect: After the alignment stage is stationary for 3 seconds, the edges of the shelf beams and the contours of the tray insertion ports are clearly visible in the point cloud, which greatly helps with the accuracy of forklift loading.
The 70° vertical FOV of the M360 is 11° wider than the 59° of the MID-360. At an installation height of 2.2m and a downward tilt angle of 15°, the M360 can cover an area within 0.5m of the ground, while the MID-360 can only reach about 0.8m. The M360 is more complete in terms of ground proximity sensing.
Built-in IMU
Both have built-in 6-axis IMUs and support PTP v2 time synchronization. For unmanned forklifts, the IMU is mainly used for positioning supplementation—as GPS signals are poor in warehouses, they need to rely on LiDAR + IMU for dead reckoning.
In actual use, both companies are sufficient, with no significant differences.
Dual Echo (M360-D)
The forklift mostly operates indoors, so dual echoes are not very useful. However, we have a scenario that can make use of it: on rainy days, when the forklift picks up goods from indoors and delivers them to a parked truck outdoors, it has to pass through a semi-outdoor channel with water on the ground.
In single-echo mode, the point cloud in the area with water can become very chaotic. After enabling dual echoes, the forward echoes hitting the water surface are filtered out, and the backward echoes pass through the water surface and hit the ground or ground obstacles, significantly improving the perception quality in the area with water.
This is not a function used every day, but it indeed avoided a situation where a forklift misjudged the ground height in a waterlogged area, causing the forks to hit the ground.
Actual Deployment Solution
Currently, all 12 of our unmanned forklifts are using the M360 (including 4 M360-D dual-echo versions). The installation method:
- One radar at the front of the roof, 2.2m in height, inclined 15°, responsible for front and ground perception.
- One single-line radar at the rear end of the vehicle supplements the reversing blind zone.
- The IMU is integrated into the M360 and does not require additional external mounting.
- Positioning Solution: 3D LiDAR + Visual QR Code + IMU Positioning Calculation
The forklift tested with the MID-360 later stabilized after adding a voltage regulator module due to power supply issues. The main considerations for choosing M360 over MID-360 were threefold: the 5cm blind zone is crucial for forklift safety, the 12~32V power supply does not require additional voltage regulation, and dual echoes are useful in semi-outdoor scenarios.
Selection recommendations
When selecting radar for unmanned forklift scenarios, I think several parameters are worth focusing on:
- Near-range blind zone: Below 5cm is better, with high precision requirements for loading.
- Power supply range: Choose a wide voltage range to avoid the need for a voltage stabilization module.
- Non-repetitive scanning: Necessary for low-speed positioning scenarios
- IP67: Basic requirement for warehouse environment.
- Vertical FOV: The larger, the better, as it can cover more space.
Both M360 and MID-360 can meet the basic requirements of unmanned forklifts. M360 has advantages in blind zones and power supply, while MID-360 has advantages in size and weight. The specific choice depends on the accuracy requirements and power supply design of your forklift.
*The above is based on actual testing experience. The parameters of MID-360 are to be taken as the latest release on the Livox official website, and the parameters of M360 are to be taken as the official specifications of TanTu Zhixing.*