With the development of automatic driving, it can be said that the technology has entered a bottleneck period. In this case, major automobile manufacturers have turned their eyes to the eye of automatic driving - sensors, especially this year, which is also known as the first year of laser radar. It can be seen that sensors now play a special role in automatic driving. So what sensors do autonomous vehicle need?

01 Sensors required for autonomous vehicle

To know what sensors autonomous vehicle need, we must first figure out what sensors it needs. To figure out what sensors it needs, we must first know what these sensors are used for autonomous driving. Presumably, at this moment, a series of functional requirements have emerged in your mind, such as positioning, obstacle detection, reversing, route planning, etc.

It is precisely because of these many functional requirements that autonomous vehicle have a terrible demand for various sensors, because autonomous vehicle, in plain terms, are copying various human functions to the car, such as human vision, smell, touch, etc. If you want to copy these functions, at the current level of technology, intelligence can be achieved by optimizing or overlaying sensors, and autonomous vehicle 'sensors need to complete this series of high intelligent operations through computing chips - actuators - feedback devices and early warning devices.

At present, the main sensors used in the field of autonomous driving include in car cameras (external cameras, built-in cameras), millimeter wave radar, LiDAR, night vision systems, etc. Among them, cameras have the lowest cost, wide application range, and can achieve the majority of ADAS functions; The price of millimeter wave radar is moderate, with high ranging accuracy and wide range, and it is not affected by weather; The advantage of LiDAR is its ability to accurately identify surrounding environmental information, but it is the most expensive for night vision; Finally, there is the infrared sensor used for night vision, which is currently only second in price to LiDAR.

In addition, the on-board cameras are also divided into three categories: monocular cameras, binocular cameras, and wide-angle cameras. The monocular cameras and binocular cameras are mainly used for the front view of autonomous vehicle, with the angle of view generally 45 degrees, and are responsible for realizing FCW, LDW, TSR, ACC, PCW and other functions, while the wide-angle cameras are used for the rear view of autonomous vehicle (rear view parking aid), built-in (eye closed reminder), side view (blind spot detection), and look around (panoramic parking, LDW) and other functions in multiple directions.

02 What kind of on-board sensors do autonomous vehicle need

Autonomous vehicle need to carry sensors according to various functions and purposes, such as long range radar, mid range radar, LiDAR (Light Detection And Ranging), camera, ultrasonic sensor, GNSS (Global Navigation Satellite System), infrared sensor, etc. The radar system is currently divided into two bands: 24GHz and 77GHz. The advantage of 77GHz lies in the accuracy of distance and distance speed testing, and the most important thing is that its resolution is also extremely accurate.

The initial purpose of Short Range Radar (SRR) was mainly to replace ultrasonic sensors and provide assistance for international autonomous driving, so it is often installed around vehicles. Of course, in the most ideal state, these radars usually use the 79GHz frequency band, with a broadband of 4GHz. However, currently, global frequency standards only allow the 77GHz frequency band+1GHz broadband. In addition, short-range radar is mainly used in blind spot detection (busy spot monitoring), lane and lane change assistants, rear radar for collision warning and collision prevention functions, parking assistance, intersection traffic flow monitoring, and so on.

When it comes to radar, LiDAR is inevitable. After all, this year is the first year of LiDAR. With LiDAR receiving more and more attention, LiDAR manufacturers are constantly developing and improving their solutions.

So what exactly is LiDAR? Lidar relies on lasers rather than radio waves. In addition to the laser emitter, this system also requires a sensitive receiver. The LiDAR system can detect static and dynamic objects and provide 3D images of the detected object. At present, LiDAR is no longer a novelty. Anyone can bring one home from a store, and its accuracy can meet general needs. However, it is not easy for it to overcome all environmental factors (temperature, solar radiation, dark nights, rainy and snowy days) and work stably. In addition, the car mounted LiDAR must be able to see up to 300 yards (approximately 274 meters) away. The most important thing is that such products must be able to be mass-produced at a market acceptable price and volume. Lidar has been applied in both industrial and military fields. However, it is ultimately a complex mechanical lens system with a 360 degree panoramic view. Due to the high individual cost of tens of thousands of dollars, LiDAR is currently not suitable for large-scale deployment in the automotive industry. Nowadays, there are two major trends in the automotive market, both of which use infrared LiDAR systems paired with MEMS systems (micro motor systems), but one LiDAR is rotating and the other is solid-state.

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