【Technical Principles】The Basic Principles of LiDAR: From Introduction to Preliminary Understanding

2025-04-11 16:33:55 manager 4

What is LiDAR？

LiDAR (Light Detection and Ranging) is a sensor that detects information such as the position and speed of targets by emitting laser beams. Its principle is similar to traditional radar, but it uses optical signals instead of radio waves. Through multidimensional data fusion, LiDAR outputs precise 3D environmental information, supporting applications such as autonomous driving and mapping.

Suzhou Suoya Robotics Technology Co., Ltd.

How Does LiDAR Work？

First, it’s important to note that LiDAR does not operate independently. It generally consists of three main modules: a laser emitter, a receiver, and an inertial positioning and navigation system. The brief working process is as follows:

Emission and Reception：

LiDAR emits short-pulse laser beams (usually infrared light) into the surrounding environment. When the laser encounters an object, it reflects and is captured by the receiver.

Distance Calculation (Two Main Ranging Technologies)：

- Time of Flight (ToF): Directly measures the time difference between laser emission and return, calculating distance using the speed of light (Formula: Distance = (Speed of Light × Time Difference) / 2). This mature, low-cost technology is widely used in automotive radar.

- Frequency Modulated Continuous Wave (FMCW): Indirectly measures distance through frequency changes, capable of directly obtaining target speed with strong anti-interference ability, though it has higher technical complexity.

Building a 3D Point Cloud Map：

By integrating laser scanning angles, timestamps, GPS positions, and INS (Inertial Navigation System) attitude data, point clouds in the local coordinate system are converted into the global coordinate system. Processed point cloud data is overlaid to generate a 3D map containing distance, reflection intensity, and spatial coordinates, providing a foundation for autonomous driving path planning or mapping.

What are the functions of real-time GPS and inertial navigation?

Real-Time GPS: Provides global absolute position information (e.g., latitude, longitude, altitude).

Inertial Navigation System (INS): During the movement of the carrier, the LiDAR itself vibrates or turns. INS uses accelerometers and gyroscopes to measure the carrier’s real-time attitude (heading, pitch, roll angles) and motion state (acceleration, angular velocity) at high frequency (up to 1000Hz), providing real-time attitude change data to correct point cloud tilt and rotation and avoid "ghosting" effects.

Fusing GPS absolute positioning with INS high-frequency attitude data ensures both long-term stable global coordinates and short-term high-precision motion tracking, maintaining positioning continuity in dynamic scenarios.

Real-time GPS and inertial navigation serve as the "spatiotemporal ruler" of the LiDAR system, ensuring that point cloud data in dynamic scenes is both accurate (precise positioning) and stable (continuous reliability). In the next issue, we will deeply analyze the core roles of laser emitters and receivers—how a single beam of light "sees" the world!

This content is compiled based on current technologies. If there are any omissions or updates, feel free to correct us! Thank you for reading and your attention!