What is single line radar? At present, single line lidar products mainly include sick company and hokuyo company.

Single line lidar is actually a high frequency pulse laser rangefinder, plus a one-dimensional rotary scanning. Features of single line lidar:

·There is only one way to transmit and one way to receive, which is relatively simple in structure and convenient in use;

·High scanning speed and angle resolution;

·Low volume, weight and power consumption;

·Higher reliability;

·Low cost;

What can a single line lidar do?

In the field of automatic driving, we basically see multi line lidar. What can a single line lidar do?

As shown in the above figure, the first car to participate in DARPA auto driving challenge in the United States was Stanford University named Stanley in 2005, which was the car that won the championship in that year. The other is the participation of Carnegie Mellon University.

At that time, they basically used the single line lidar of sick company. In particular, there are five lidars on the top of Stanford University's racing car. We can think of it as the "ancestor" of multi line lidar, but it uses five single line lidars to realize the function of multi line lidar.

After velodyne launched 64 line lidar in 2007, many autonomous vehicles basically use velodyne's products. But does this mean that there is no market for SLR in auxiliary or automatic driving?

I don't think so. Because single line lidar has its own characteristics, for example, in high repetition rate and high angle resolution, multi line lidar is difficult to achieve the same technical indicators.

Above is a photo of this year's participation in the Changshu China smart car future challenge. It can be seen that in addition to using velodyne multi line lidar and ibeo multi line lidar, they have all installed sick single line lidar. Because Xi'an Jiaotong University cooperates with us, it uses our single line lidar.

In terms of pedestrian detection, obstacle detection (small target detection) and obstacle detection in front, single line laser has much more advantages than multi line laser radar, because the angular resolution of single line laser radar can be higher than that of multi line laser radar, which is very useful in detecting small objects or pedestrians.

The picture above is a screenshot of the propaganda video of single line lidar made by ibeo at that time. In the picture, one of its functions is forward anti-collision. For example, on the road, a car suddenly appears on the left side. After the lidar detects the position and size of the car, it can automatically avoid.

This technology is very useful in intelligent robots and service robots, and it is also a hot field at present.

Above is the application of lidar in lane detection and lane yaw warning. Maybe many people will ask a question, why do we use lidar to do lane detection instead of camera? Isn't ADAS algorithm very mature? Why do we have to use lidar?

This is because the camera is particularly vulnerable to background light or strong light interference. For example, when we walk on the Boulevard, if the shade falls in the spot of sunlight, and then combined with the white lane line, we are very difficult to identify the lane line, and the recognition probability is very low under the condition of complex light or strong light, and the algorithm is very complex.

So, what's the advantage of using lidar for lane detection? First, we use infrared laser, which has much lower radiation than visible light. Second, we will add a very narrow filter to remove the strong background light directly. Then we use infrared light to detect it. In this way, we can get a very high-quality lane line image. Through the gray level of the image, it is very easy to detect the lane line. In other words, the performance of lidar for lane line detection is higher than that of camera.

The application of SLR in assistant driving is pedestrian detection, in fact, it is also a forward anti-collision application, which is basically similar to automobile anti-collision. Because the angular resolution of single line lidar is higher than that of multi line lidar, it can find pedestrians in advance in a long distance, and leave more warning time for the control system or the driver.

Application of ACC (stop & go). This function is especially applicable in the current situation of urban traffic congestion in China. It can obtain the accurate distance information of the vehicle in front by directly detecting the vehicle movement in front through the forward lidar, and then automatically follow by controlling the vehicle.