Lidar is one of the most common lidar sensors used in modern robots. Its main function is to detect the distribution of surrounding obstacles.

According to the measured latitude, it can be divided into single-line radar and multi-line radar. According to the measurement principle, it can be divided into triangular ranging radar and TOF ranging radar. According to the working mode, it is divided into mechanical rotating radar and solid-state radar.

Although there are many types of lidar, the data format presented in ROS is the same. There will only be differences in data completeness and accuracy. The working principle of lidar. We take the simplest TOF lidar as an example and place an obstacle in front of it. The lidar is usually installed in the center of the mechanical synthesis and is protected by the chassis structure. The mechanical structure of lidar is divided into It is made of two parts, one part is the fixed base.

The other part is a rotatable synchronized structure. An infrared laser transmitter and an infrared laser receiver are installed on the head of the radar. When the radar is working, an infrared laser will be output from the transmitter.

After this beam hits an obstacle, it will be reflected back and used by the radar to measure the distance between laser emission and reception through a timer. After the lidar measures the distance to the obstacle in one direction, it will turn to other angles and then emit an infrared laser. Receive the reflected light beam, then change the angle, and then continue to rotate, always synchronizing this operation. Until the radar probe rotates a full circle, that is, a 360-degree detection of surrounding obstacles is completed.

This rotation detection task will be performed over and over again. As long as the laser beam detection frequency is high enough and fast enough, the distribution of surrounding obstacles can be refreshed in real time, and we will see the obstacle outline lattice distribution map.