There's a new twist on lidar technology

Car driving is divided into five stages, and the popularity of ADAS is a prerequisite for future driverless driving. In the current ADAS application popularization stage, multi-sensor fusion is the future trend. These include ultrasonic radar, camera, infrared, Lidar, millimeter wave radar, etc. Millimeter wave radar will be the first to become the main sensor of ADAS system. Among them, radar is seen as a key technology for autonomous vehicles, which is preparing for the golden age of the automotive sensor industry. How will radar sensor technology shape the car of the future?

Nowadays, the current radar technology is very hot, and the companies in this field are also emerging in endlessly, and the most promising product applications are unmanned directions, as well as applications in intelligent docks, high-precision maps and other fields. Nowadays, radar products are also varied, and the size design at home and abroad is getting smaller and smaller, and the appearance is getting more and more beautiful. At present, the common radar technology is TOF (Time of Flight) technology. The principle is also very simple, by continuously sending light pulses to the target, and then using the sensor to receive the light returned from the object, by detecting the flight (round trip) time of these transmitted and received light pulses to get the distance of the target object. At the 2018 China IC Ecological Summit Forum in Qingcheng Mountain, Pan Weiqing from Hangzhou Ailida Technology Company introduced their achievements in Lidar.

For TOF technology, Pan Weiqing also pointed out the existing problems. He said that in the field of unmanned vehicles, the first problem with this technology is in terms of anti-interference, the current lidar uses direct detection, responding to all the light entering the detector, but if the radar is facing the sun when it is working, then it is susceptible to sunlight, radar and human eyes are the same, the light intensity is too high, it can not see the target. This poses a security risk; The other is in the number, lidar is basically a single car or a few cars in the application, if the future is really used in commercial popularity, then most of the cars on the road will use such radar, so that it is impossible to identify the pulse of the nearby car or their own signal echo, resulting in interference problems; There are also hidden dangers in the detection range, and today's radar takes into account that the human eye can safely display, and the emitted light rate is limited by the human eye and cannot be too high. As a result, radar detection distances of 150 to 200 meters are difficult; In addition, the radar is to be made of solid state, then the most expected program is OPA (phased array), this program also has requirements for the radar and the host, and the size of the light aperture of the scan is small, which means that it will bring a certain loss to the radar, further shortening the detection distance of TOF radar.

Based on these factors, Alaida Technology company has developed a new radar technology called FMCW. Its signal is continuous, the frequency is linear and the frequency is modulated on the same frequency, which means that there is a difference between the transmission frequency and the received frequency, and the difference between its two waves can be detected by optical mixing detection, and the distance can be measured by frequency conversion. Through this principle, the radar power is relatively far, and the detection distance under the transmission power is 50 to 200 milliwatts can be more than 1 km, and it can completely work directly under the sun without any light interference. Another advantage is that the speed can be accurately obtained at the same time, and the speed measurement accuracy can reach 0.1 m/s. Its key technology is the frequency modulation technology of light, coherent reception, signal analysis, is a relatively advanced coherent lidar.

Compared with TOF technology, FMCW has stronger anti-jamming ability. Weiqing Pan said: "Its effective exploration sensitivity is very high, direct effective detection can accurately test only 10 photons." The requirement of working distance has far exceeded the requirements of car companies. In addition, we take the 1550 band to transmit higher power, detect speed information, and be fully compatible with solid-state scanning. The radar can also be integrated with millimeter wave at the chip level. The working mechanism of the radar is very similar to that of millimeter wave, and it can be shared in many modules, including signal modulation module and processing module. And the technology has very good optical connectivity."

The automotive industry is experiencing a new wave of high-tech applications, and radar has an impressive technology roadmap that allows for significant resolution improvements, as well as sensor miniaturization and low cost. It is of great significance to the development of intelligent driving. In the near future, you may really feel the excellent performance of radar technology on ADAS, and maybe you will love it because of it...