A car needs to realize automatic driving, the important point is to be able to intelligently avoid obstacles, collect information about the size, shape and location of obstacles, in order to use the algorithm to plan the safest route. A self-driving vehicle requires many inductive measurement units to work closely with the central processing unit. Among them, radar equipment, lidar, camera and inertial measurement unit are several indispensable components, of which lidar mainly plays a role of accurate detection.
Lidar is a car's perception detection system, which is the eyes of self-driving vehicles, capable of collecting environmental information and identifying objects and dangerous conditions. The combination of different subsystems such as lidar and millimeter-wave radar, inertial measurement unit, camera, and ultrasonic sensor has built a basic framework for the successful realization of autonomous driving and a highly safe and reliable advanced driver assistance system.
Lidar is an active measurement device that emits a laser beam to detect the target's spatial position. According to the detection principle, lidar is divided into single-line (two-dimensional) lidar and multi-line (three-dimensional) lidar. The single-line laser radar scans the area by sending a laser scanning line, and the multi-line laser radar scans the area by sending two or more laser scan lines. Multi-line lidar can detect the spatial distance and azimuth of the target, and can describe the three-dimensional environment model through the point cloud, providing a detailed shape description of the detected target. It is reported that the multi-line lidar mainly includes 4-line, 8-line, 16-line, 32-line and 64-line. The more beams emitted by the lidar, the more point clouds are collected per second, and the cost is higher. For example, the price of 64-line lidar for some lidar manufacturers is 17.5 times that of 16-line lidar. Lidar has developed three generations of products, including the first-generation mechanical scanning lidar, the second-generation hybrid solid-state lidar, and the third-generation pure solid-state lidar. The third generation of pure solid-state lidar can greatly reduce the cost of lidar, and make the application of lidar in autonomous vehicles popular.
Lidar generally consists of four parts: laser emission, laser reception, information processing and scanning system. Compared with millimeter-wave radar, lidar has higher detection accuracy, but has stricter requirements on meteorological conditions. The use of lidar in vehicles places stringent requirements on lidar system components such as detectors and lasers, especially heat resistance and reliability throughout the life cycle of the vehicle.