Unitree 4D LiDAR-L1 User manual

Unitree
4D LiDAR-L1
User Manual
2023.04
v 1.0

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Download Open-source Sdk

Product Overview
Introduction
Working Principle
Component Description
Effective Field of View (FOV) Range
Installation Precautions
Installation Dimensions
Wiring
Coordinate System
Point Cloud Data
Operation Status and Modes
Unilidar
Unilidar SDK
Storage
Transportation
Maintenance
4-Pin Connector
Maintenance
Installation
Usage
Storage, Transportation, and Maintenance
Troubleshooting
After-Sales Warranty Information
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Parameter Specifications 14
CONTENTS
2023 Unitree Robotics. All rights reserved. 1

Product Overview
Introduction
Unitree 4D LiDAR-L1 is a cost-effective, safe, and reliable 4D LiDAR (3D position + 1D grayscale) that
can achieve high-speed laser ranging sampling at 21,600 times per second. It can be widely used in
robotics, smart cities, smart toys, logistics, and other fields, supporting functions such as mapping,
positioning, recognition, obstacle avoidance, environment scanning, and 3D reconstruction.
The L1 radar can detect objects as close as 0.05 meters and as far as 30 meters away (90% reflec-
tivity).
The L1 unit is compact and lightweight, weighing only 230 grams, making it suitable for general
robot environment scanning, positioning, mapping, navigation, and obstacle avoidance.
The L1 has outstanding ultra-wide-angle scanning capabilities, with a field of view (FOV) expanding
to 360 ° horizontally and 90 ° vertically, enabling three-dimensional space detection of a hemispheri-
cal field of view. Its application range can be expanded to more commercial scenarios.
The L1 has an IMU module with built-in 3-axis acceleration and 3-axis gyroscope, supporting a push
frequency of 250Hz.
The L1's azimuthal scanning frequency is 11Hz, and its vertical scanning frequency is 180Hz, with an
effective sampling frequency of 21,600 points/second. The L1 not only has excellent performance
but also has high reliability, meeting the working environment temperature range of -10℃~60℃ and
IEC-60825 Class 1 eye safety level.
2023 Unitree Robotics. All rights reserved.
2

Working Principle
The L1 radar mainly consists of the laser emission and ranging core, reflector, high-speed rotating
motor, and low-speed rotating motor. In the working state, as shown in the diagram, the rotating
directions of the high-speed and low-speed rotating motors are as shown in the figure.
The communication and power supply interfaces of the L1 are connected through a conversion
module, which includes a power supply port and a Type-C port. Users can supply power through a
power adapter and obtain scanning ranging data through the Type-C port. The L1 is equipped with a
conversion module, power adapter, and data cable for users, eliminating the need for a complex
power supply system and debugging cables, reducing usage costs.
The L1 uses laser flight time ranging technology, combined with a high-speed laser acquisition and
processing system, to achieve a ranging action of 21,600 times per second. In each ranging action,
the L1 emits ns-level narrow-pulse infrared laser signals. The reflected light from the target object is
received by the radar's laser acquisition system, and after analysis and processing by the processor,
the distance value and current angle information between the illuminated target object and the L1
are output from the communication interface.
3
2023 Unitree Robotics. All rights reserved.
Unitree4D LiDAR-L1 User Manual
Schematic Diagram of Working Principle
Direction of High-Speed Motor Rotation Direction of Low-Speed Motor Rotation
d

Component Description
Optical Window
The laser beam emits outward through the window, scanning objects within the FOV range.
Outlet
The end of the cable is a 4-pin connector that, when combined with the conversion module, can
quickly test the performance of the laser detection and ranging instrument. It is recommended
that users customize and use cables suitable for their scene requirements based on the plug
wire sequence to improve the system's protection capabilities (such as dust and water resis-
tance). Please refer to the Interface Definition section for the pin sequence of the 4-pin connec-
tor.
Locator slot
When designing a fixed bracket, the positioning point can be used to improve the overall posi-
tioning accuracy. Please refer to the Installation Dimensions section for specific dimensions.
M3 Mounting Hole
The L1 can be fixed to a suitable position using M3 screws through this mounting hole.
2023 Unitree Robotics. All rights reserved.
Unitree4D LiDAR-L1 User Manual
4
1.
2.
3.
4.
1
2
34

Interface Definition
2023 Unitree Robotics. All rights reserved.
4-Pin Connector
The L1 output cable is a 4-pin serial port, which can be connected to the L1 using the included con-
version module, power adapter, and data cable to realize power connection, control signal transmis-
sion, and data transmission. Users can also replace the conversion module with other cables ac-
cording to their own needs to improve the system's protection capabilities (such as water and dust
resistance).The specification of the serial port socket is GH1.25mm 4PIN.
The pin sequence definition of the L1's 4-pin serial port is as follows:
5
4-Pin Serial Port Diagram and Pin Numbering Diagram
PIN NO. Signal Attribute Description Cable Color Function
1VCC Power Supply DC 12V power supply Red Power cable
2GND Ground Ground White Power cable
3 RX Input 3.3V Ranging core
serial port input Green Functional cable
4 TX Output 3.3V Ranging core
serial port output Black Functional cable
4
3
2
1

2023 Unitree Robotics. All rights reserved.
Installation
Effective Field of View (FOV) Range
The L1 includes a high-speed motor and a low-speed motor. The high-speed motor drives the reflec-
tor to rotate, realizing vertical measurement within a 180 ° range. The low-speed motor then drives
the measuring core to rotate 360 ° , thus achieving a hemispherical super-wide-angle scan of
360*90° . It can measure the three-dimensional space above the radar in a 360° range, as shown in
the figure below. When installing, please pay attention to the effective range of the FOV to avoid
obstructing the FOV area.
Please note that the point cloud density of the L1 varies in different FOV areas, with higher den-
sity near the center. Please refer to the figure below for details.
6
Effective FOV Range of L1
Point Cloud Density in Different FOV Areas of L1
Horizontal Direction Vertical Direction
360°
90°

2023 Unitree Robotics. All rights reserved.
Unitree4D LiDAR-L1 User Manual
Installation Precautions
Before installing the L1, please read the following precautions:
7
Dust or dirt on the optical window may affect the performance of the laser detection and rang-
ing instrument. We recommend using alcohol or a cleaning cloth to clean it according to the
maintenance section of this document. After cleaning, proceed to installation.
The FOV of the laser detection and ranging instrument should not be obstructed during installa-
tion, even if transparent glass is installed in front of the window, it may still affect the perfor-
mance of the laser detection and ranging instrument.
The installation direction of the laser detection and ranging instrument is not limited and can be
installed using its lower surface.
The installation structure of the laser detection and ranging instrument can only ensure its own
reliability, and the body of the laser detection and ranging instrument cannot bear additional
loads.
The laser detection and ranging instrument requires airspace design on all sides during installa-
tion to prevent poor air flow from affecting heat dissipation. It is recommended that the airspace
size around the laser detection and ranging instrument is not less than 10mm.
When waterproofing is required for the usage scenario, the laser detection and ranging instru-
ment needs an additional waterproof protective bracket. The schematic diagram of waterproof
protection for both upright and inverted installation is as follows:
1.
2.
4.
3.
5.
6.
Waterproof Protection Schematic Diagram
Inverted InstallationUpright Installation

2023 Unitree Robotics. All rights reserved.
Unitree4D LiDAR-L1 User Manual
Mechanical Dimensions of L1
Unit: mm
Installation Dimensions
The bottom of the L1 has four M3 mounting holes with a depth of 6mm. Please refer to the following
L1 size and mounting hole size diagram to install the L1 in the appropriate position.
Weight and Size of L1:
8
Weight
Size
230g
75 (W) x 75 (D) x 65 (H) mm
60 51
22.5 22.5
64 x M3
3.50
65
32
44.50
24
75

Coordinate System
TheCartesian coordinate systemof L1, denoted as 0-XYZ, is defined as shown in the diagram below. O
is the origin of thepoint cloud coordinatesystem, located at the bottom center position, with the +X
axis pointing in the opposite direction of the outlet, and the +Y axis pointing counterclockwise 90 ° from
the +X axis. O-XYZ is thepoint cloud coordinate systemof L1(The origin andXYZ coordinate systemof
the IMU can be found in theL1 3D model, and itsXYZ axesare parallel to thepoint cloud coordinate
system.)
Usage
Wiring
The 4-pin connector of the L1 provides external power and data transmission. Please refer to the
Interface Definition section for the specific pinouts. To temporarily test or use the L1, we recommend
using the included adapter module, power adapter, and data cable for connection and usage as fol-
lows:
a. Insert the 4-pin serial port of the L1 into the adapter module.
b. Insert the power adapter into the power port of the adapter module for power supply.
c. Insert the Type-C interface of the data cable into the data communication port of the adapter
module and connect the other end to a personal computer.
The adapter module, power adapter, and data cable are included in the package and can be used
for power supply, control signal transmission, and data transmission. Alternatively, you can use
other cables according to your needs to improve usability and system protection (such as dust and
waterproofing).
When debugging, be sure to place the L1 radar on the included rubber pad and place the rubber
pad on a flat surface to ensure stable operation and prevent collisions and falls.
9
Unitree 4D LiDAR-L1 Coordinate Definition
Unitree4D LiDAR-L1 Adapter Module Connecting to an External Power Source
USB to Type-C Cable
Unitree
O
Z
X
Y
360°
X
Y

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Unitree4D LiDAR-L1 User Manual
10
Working state
Sampling status
Standby status
Interference status
Description
Point Cloud Data
By default, the L1 starts outputting point cloud data as soon as it is powered on. The point cloud
data includes distance values, angles, reflectivity, IMU data, and working status data.
Point cloud data is the comprehensive result of all the point clouds detected by the laser ranging
instrument on the surface of the measured object in the field of view. Each point cloud data mainly
includes the following information:
Distance value: the actual distance between the sampling points, in millimeters.
Angle: the angle between the sampling point and the L1's own orientation, in degrees.
Reflectivity: the reflectivity of the object detected.
IMU data: 3-axis accelerometer and 3-axis gyroscope data.
Working status data: current speed, voltage, temperature, and other data of the laser ranging
instrument.
Working Status and Working Modes
The working status of the L1 refers to the current state of the laser ranging instrument, while the
working mode refers to the target working mode set by the user.
Working Status Description
The working status of the L1 includes sampling status, standby status, and interference status, as
detailed in the table below.
Working Mode Description
The working mode of the L1 refers to the target working mode set by the user. The L1 has two work-
ing modes that users can set: normal mode and standby mode. Users can set different working
modes through Unilidar or Unilidar SDK. The default mode for L1 when first used is the normal mode.
If L1 loses power and is turned on again, it will revert back to the default normal mode.
The laser ranging instrument has been powered on and is functioning normally
(emitting laser beams).
After setting the standby mode, the laser ranging instrument enters the standby
status with a power consumption of less than 1W. The LED light is turned off, the
high-speed motor stops rotating, the low-speed motor stops rotating, and only IMU
data is output.
If the laser ranging instrument is forcefully stopped due to external forces, the point
cloud cannot be used. However, when the external forces are released, the L1 will
automatically resume rotation and point cloud data output.

2023 Unitree Robotics. All rights reserved.
Unitree4D LiDAR-L1 User Manual
Unilidar is an operating software that can display and parse 3D point clouds in real-time, and sup-
ports advanced functions such as product settings and external parameter adjustments. By using
Unilidar software, users can perform simple graphical debugging. Before using Unilidar, it is neces-
sary to install the driver, which can be downloaded from www.unitree.com to view point cloud
images. Unilidar currently supports Windows® (64-bit).
For Windows users: unzip the file, open the unzipped folder, double-click on the program named
"CP210xVCPInstaller_x64" to install the driver, and run the Unilidar.exe program as an administrator.
For more detailed instructions on how to use Unilidar, please visit the official website at www.uni-
tree.com and download the "Unilidar User Manual" for more information.
The L1's LED light ring has eight modes to choose from, including command mode, slow forward
rotation, fast forward rotation, slow reverse rotation, fast reverse rotation, three-segment flip,
three-segment breathing, and six-segment breathing. Users can set different LED modes through
Unilidar or Unilidar SDK.
The default LED mode is six-segment breathing, and when using Unilidar point cloud software, it will
automatically switch to command mode. After the L1 is powered off and on again, it will maintain
the last used LED mode.
When using command mode, users can customize the state of each LED light bead. For detailed
configuration methods, please refer to the relevant chapters of the "Unilidar User Manual" and Unil-
idar SDK documentation.
Unilidar
LED Modes
In addition to using Unilidar to view real-time point cloud data, users can also use the Unilidar SDK
software development kit to apply the point cloud data obtained through the laser ranging instru-
ment to their own custom scenarios. This can achieve the following functions:
· Configure the laser ranging instrument: configure and query the laser ranging instrument parame-
ters and status information;
· Obtain point cloud data: point cloud coordinate data generated by the laser ranging instrument.
Visit https://www.unitree.com/en/download for more detailed information about the Unilidar SDK
documentation.
Unilidar SDK
11

2023 Unitree Robotics. All rights reserved.
Storage, Transportation, and Maintenance
Storage
The storage temperature range for the L1 is -20℃~60℃. Please store it in a dry and dust-free envi-
ronment, and pay attention to the following:
· Do not expose the product to toxic, harmful, or corrosive environments.
· Handle the product with care when storing, and avoid dropping it.
· For devices stored for more than three months, regularly check the appearance and interfaces to
avoid abnormal conditions when using.
Transportation
Before transportation, please carefully check whether the product is securely installed and then
pack it in the packaging box. It is necessary to put buffer foam in the packaging box, and ensure
that the packaging box is dry and clean, without moisture. During transportation, handle the prod-
uct with care, avoid collision, impact, or dropping.
Maintenance
The L1 has good reliability and stability, and under normal use, the probability of failure is small. It
only requires cleaning of the optical window of the laser ranging instrument. If the output area of
the radar is contaminated (such as dust, mud, etc.), it may affect the quality of the data generated
after scanning objects. In this case, it is necessary to clean the radar. Please follow the following
steps to clean it:
First, use a clean lens cleaning cloth to gently wipe the optical window. If there are still visible stains
on the window, then use a small amount of alcohol on the cleaning cloth to gently wipe the
window.
12

2023 Unitree Robotics. All rights reserved.
Problems
Unable to detect the
serial port connected to L1
L1 stopped rotating due to
external interference
Solutions
FAQ
After-sales warranty information
If there is a problem during use, please refer to the following table for solutions. If the problem
cannot be resolved, please contact an authorized dealer of Unitree or Unitree.
Visit https://www.unitree.com/terms for more information on Unitree 4D Lidar-L1's warranty
information.
· Confirm that all cables are correctly connected.
· Confirm whether the adapter is suitable. The power supply require-
ment for the L1 is 12V, 1A.
· Confirm whether the Unilidar driver program is installed.
After the above confirmations, if the serial port connected to the L1
still cannot be detected, try restarting the L1 and Unilidar software.
· Confirm that all cables are correctly connected.
· Confirm whether the adapter is suitable. The power supply require-
ment for the L1 is 12V, 1A.
If the problem still exists, try restarting the L1 and Unilidar software.
· Usually, when external force is released, the L1 will automatically
resume rotation.
· Try restarting the L1.
13
Able to detect the serial
port connected to L1, but
unable to open the serial
port or start sampling

2023 Unitree Robotics. All rights reserved.
14
Parameter Specifications
Unitree 4D LiDAR
[1]
[2]
[3]
[4]
[5]
Model L1 PM（Precision Measurement）
L1 RM（Remote Measurement）
Eye Safety Rating Class 1(IEC60825-1:2014) Eye Safety
Max Range 20M（L1 PM @90% reflectity）， 30M（L1 RM @90% reflectity）
10M（L1 PM @10% reflectity）， 15M（L1 RM @10% reflectity）
Near Blind Zone
FOV
Sampling Frequency
Effective Frequency
Scanning Method
4D Information
Horizontal Scanning Frequency
Vertical Scanning Frequency
Communication Interface
Communication Baud Rate
Measurement Accuracy
Measurement Resolution
IMU Sampling Rate
IMU Reporting Frequency
Attitude Perception Dimension
LED Ring Resolution
LED Ring Refresh Rate
Anti-Strong Light Ability
Operating Environment Temperature
0.05m
360°* 90°
43200 points/s
21600 points/s
Contactless Brushless Mirror Scanning
3D Position + 1D Grayscale
11Hz
180Hz
TTL UART
2000000 bps
±2.0cm
8 mm
1kHz
250Hz
3-axis Accelerometer + 3-axis Gyroscope
1°
11Hz
100Klux
-10℃-60℃
Laser Wavelength 905nm

2023 Unitree Robotics. All rights reserved. 15
The instantaneous peak power of the laser is 25W, but the actual average power used will be much lower than this value, and
it is driven by a pulsed method, which only emits for a very short time to ensure the safety of humans and pets and meet the
Class I level laser safety standard.
The typical value of reflectivity is shown here, and the actual value depends on environmental conditions and target object
characteristics.
The laser ranging instrument can detect and output point cloud data when the distance to the target object is 0.05m. However,
due to the inability to guarantee detection accuracy, this data is for reference only.
To ensure the effective detection of objects with different reflectivities within the range, there may be a slight decrease in point
cloud accuracy at some locations. The test conditions are as follows: environment temperature of 25℃, target object reflectivity
of 90%, and test distance of 15m.
The performance of L1 will slightly decline in high and low temperature environments, strong vibration, foggy weather, etc. In
addition, long-term high-temperature operation may affect product performance or even cause product damage. It is recom-
mended to increase cooling measures to ensure that the housing temperature does not exceed 60℃. When the temperature is
too high, the over-temperature protection mechanism will be triggered, and L1 will issue an over-temperature warning. When
the over-temperature is severe, L1 will stop working.
The protective effect of L1 varies greatly under different installation angles. Please increase external protection according to the
actual installation angle. Damage caused by improper installation or external protection is not covered by the warranty.
The stable power and peak power under different environments are different.
[1]
[2]
[3]
[4]
[5]
[6]
[7]
Storage Environment Temperature
Protection Level
Power
Operating Voltage
Size
Weight
-20℃-60℃
IP54
6W（Environment Temperature25℃）
12V DC
75 (width) x 75 (depth) x 65 (height) mm
230g
[6]
[7]

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