I. Basic Components of LiDAR
LiDAR is a device that uses laser signals to measure distances. Its basic components include a laser, a scanning mechanism, a receiver, a signal processing unit, and a data output unit.
(1) Laser: The core component of lidar, which outputs a monochromatic, coherent, high-energy laser beam with a small divergence angle. Commonly used lasers include gas lasers, solid-state lasers, semiconductor lasers, etc.
(2) Scanning mechanism: used to scan the laser beam. There are two types of scanning methods: mechanical scanning and electronic scanning. Mechanical scanning uses a rotating mirror for scanning, while electronic scanning is based on an array of several lasers and laser receivers, and scanning is achieved by adjusting each laser and receiver individually.
(3) Receiver: Receives the laser signal reflected back from the target and converts its electrical signal into a digital signal.
(4) Signal processing unit: performs filtering, amplification, time-domain processing, frequency-domain analysis and other processing on the signal received by the receiver to obtain information such as the target's distance, speed and angle.
(5) Data output unit: Outputs the processed data to the user, which can be in the form of digital signal, image data, sound signal, etc.
II. Classification of LiDAR by Function
1. Laser ranging radar
Laser ranging radar determines the distance between the object and the test point by emitting a laser beam at the object being measured and receiving the reflected wave, recording the time difference. Traditionally, laser radar has been used in industrial safety detection, such as the laser walls seen in science fiction films, where the system immediately reacts and issues a warning when someone intrudes. It also has wide applications in spatial mapping. However, with the rise of the artificial intelligence industry, laser ranging radar has become an indispensable core component of robots. Used in conjunction with SLAM technology, it helps robots perform real-time positioning and navigation, enabling autonomous movement. The RPLIDAR series developed by SLAMTEC, used with SLAMware modules, is a typical example of autonomous positioning and navigation for service robots. Within a 25-meter ranging radius, it can perform tens of thousands of laser ranging operations per second with millimeter-level resolution.
2. Laser speed measurement radar
Laser speed radar measures the speed of an object by performing two laser ranging operations with a specific time interval between the object and the target object.
There are two main categories of methods for measuring velocity using lidar. One type is based on the lidar ranging principle, which involves continuously measuring the target distance at regular time intervals. The velocity value is obtained by dividing the difference between two target distances by the time interval, and the direction of the velocity can be determined by the sign of the distance difference. This method has a simple system structure but limited measurement accuracy and can only be used for hard targets with strong laser reflection.
Another type of velocity measurement method utilizes Doppler frequency shift. Doppler frequency shift refers to the frequency difference between the received echo signal and the transmitted signal when there is a relative velocity between the target and the lidar.
3. Laser imaging radar
Laser imaging radar can be used to detect and track targets, and obtain target location and velocity information. It can accomplish tasks that ordinary radar cannot, such as detecting submarines, mines, and hidden military targets. It is widely used in military, aerospace, industrial, and medical fields.
III. Future Prospect Analysis of LiDAR
LiDAR has a very wide range of applications. This is mainly reflected in the following aspects:
(1) Autonomous driving: Autonomous vehicles are one of the main application scenarios for LiDAR. In autonomous vehicles, LiDAR can achieve accurate distance measurement and 3D reconstruction, and can detect obstacles, pedestrians, vehicles, etc., to ensure driving safety.
(2) Night vision: LiDAR has good penetration and anti-interference performance, so it can be used in night vision systems. LiDAR can identify distant objects even in foggy or hazy weather conditions.
(3) Surveying: LiDAR can quickly and efficiently acquire three-dimensional spatial data and is widely used in indoor and outdoor building surveying, topographic surveying, mine surveying, marine surveying and other fields. It has important application value and economic value.
(4) Security check: LiDAR can detect the shape, size and other features of objects and can be applied to security check occasions, such as scanning luggage and scanning people, which can improve security check speed and efficiency.
(5) Robots: LiDAR can be used in robots to achieve environmental perception and obstacle avoidance. Robots can use LiDAR to acquire environmental maps, detect obstacles, plan paths, etc., to achieve autonomous navigation.
Therefore, it can be seen that LiDAR has broad application prospects in fields such as automotive, aerospace, industry, security inspection, and robotics. Currently, with continuous technological development, the performance and application scope of LiDAR will continue to expand, and it is expected to become an important emerging technology in the future.
