I. LiDAR
LiDAR (Light Detection and Ranging) is a system that integrates laser, GPS (Global Positioning System), and IMU (Inertial Measurement Unit) technologies. Compared to ordinary radar, LiDAR has advantages such as high resolution, good concealment, and stronger anti-interference capabilities. With the continuous development of technology, the application of LiDAR is becoming increasingly widespread, and it can be seen in fields such as robotics, autonomous driving, and driverless vehicles. Compared to millimeter-wave radar, which relies heavily on algorithms, requires massive amounts of data for training, is greatly affected by environmental factors, has limited visual and recognition accuracy, and struggles to determine the specific outlines of obstacles, LiDAR is clearly superior because it can accurately perceive the three-dimensional information of the surrounding environment, has a detection accuracy within centimeters, can accurately identify the specific outlines and distances of obstacles, and does not miss or misjudge them.
However, compared to other sensing sensors, LiDAR also has a significant drawback: its high price. Generally, two main factors influence the price of LiDAR: the number of beams and the purchase quantity. Based on the number of beams, LiDAR can be divided into single-beam LiDAR and multi-beam LiDAR. The difference lies in the number of beams. Multi-beam LiDAR, also known as 2.5D/3D LiDAR, can scan the vertical field of view to obtain depth information of the environment. Correspondingly, its price is directly proportional to the number of beams; the more beams, the higher the price. Single-beam LiDAR, or 2D LiDAR, generates only one scan line per scan, obtaining 2D data and scanning only on a plane. However, single-beam LiDAR boasts a simple structure, ease of use, fast ranging speed, stable and reliable system, low power consumption, small size, and relatively low price, sufficient to meet the cost and performance requirements of fields such as service robots.
Driven by demand, single-line lidar has been quite popular in recent years, and companies and products in this field have been emerging one after another. However, due to factors such as technology and raw materials, cost-effective industrial-grade single-line lidar remains scarce.
II. What are the differences between single-line and multi-line lidar?
Multi-line lidar refers to a laser rotating rangefinder that simultaneously emits and receives multiple laser beams. Currently, there are 4-line, 8-line, 16-line, 32-line, 64-line, and 128-line lidars on the market. Multi-line lidar can identify the height information of objects and obtain 3D scan images of the surrounding environment, and is mainly used in the field of autonomous driving.
In the field of autonomous driving, multi-line LiDAR mainly plays the following two core roles:
3D modeling and environmental perception: Multi-line LiDAR can scan the 3D model of the environment around the car. By using relevant algorithms to compare the changes in the environment between the previous frame and the next frame, it is relatively easy to detect surrounding vehicles and pedestrians.
SLAM localization enhancement: Simultaneous mapping (SLAM) is another major feature. By comparing the global map obtained in real time with the features in the high-precision map, the positioning accuracy of the vehicle can be enhanced and autonomous navigation can be achieved.
Currently, most LiDAR systems used in autonomous driving are manufactured overseas, including companies like Velodyne and Quanegy from the United States, and IBEO from Germany. Multi-line LiDAR systems, spearheaded by Velodyne, are expensive, costing tens of thousands of US dollars or more, making them unaffordable for most automakers.
In comparison, single-line LiDAR is much cheaper. Single-line LiDAR refers to radar where the laser source emits a single beam. Currently, it is mainly used in the robotics field, primarily in service robots, to help them avoid obstacles. It boasts fast scanning speed, high resolution, and high reliability. Compared to multi-line LiDAR, single-line LiDAR reacts faster in terms of angular frequency and sensitivity, resulting in greater accuracy in measuring the distance to surrounding obstacles. However, single-line LiDAR can only scan in a planar plane and cannot measure object height. Currently, it is mainly used in common applications such as robotic vacuum cleaners, food delivery robots, and service robots in hotels.
Unlike multi-line LiDAR in the field of autonomous driving, single-line LiDAR used in robotics in my country is relatively mature. Single-line LiDAR, represented by Shenzhen Buzhi Technology, can achieve a measurement radius of 50 meters. At the same time, it can effectively avoid interference from ambient light and strong sunlight, and can be used stably both indoors and outdoors. In addition, its body is ultra-thin, compact and lightweight, making it suitable for more and larger application scenarios.
In summary, multi-line LiDAR has more complex applications and higher performance requirements, but its high price makes it unaffordable for most companies. In contrast, single-line LiDAR has a simpler structure, lower cost, and is more likely to meet the needs of service robots, offering greater accuracy in terms of distance and precision.
