It is important to realize the perception of unmanned sensors, currently including Ford, GM, Volvo, most of the car companies of driverless cars are equipped withburning laser radar. Recently Baidu, Google and other domestic and foreign giant moves frequently, have committed to the development and commercialization of laser radar. With the industry awareness of the importance of laser radar constantly, and no release driving huge demand, the future will have more capital and resources into the field of laser radar.
So, what is the radar?
Use Laser as the light source, the main laser radar by means of photoelectric detection technology. Dynamic high powered laser radar remote sensing equipment. Laser radar is laser technology and modern photoelectric detection technology combined with the advanced detection methods. The system consists of emitting and receiving system, information processing etc.. The laser transmitter system is in various forms, such as carbon dioxide laser, neodymium doped yttrium aluminum garnet laser, semiconductor laser Solid state lasers and optical beam expanding unit and wavelength tunable; the receiving system adopts the photoelectric detector and telescope in various forms, such as photomultiplier tube, semiconductor photodiode, avalanche photodiode, infrared and visible multi detector etc..
Laser Sight using pulsed or continuous wave 2 ways of working, according to the detection principle of different detection methods can be divided into Mie scattering and Rayleigh scattering, Raman scattering, Brillouin scattering, fluorescence, laser Doppler radar. It is a set of laser, global positioning system (GPS) and inertial navigation system (INS) technology and a system of three, is used to obtain the data and generate accurate DEM. The combination of these three technologies, can be highly accurate positioning Laser beams Hit the spot on the object. It is divided into the maturity to obtain the digital elevation model (DEM) for the LIDAR system and the terrain have been applied hydrological LIDAR system to obtain DEM under water, a common feature of these two systems are detected and measured by laser.
Laser ranging ability itself has a very precise, the precision can reach several centimeters, and the accuracy of LIDAR system in addition to the laser itself factors, but also depends on the laser, GPS and inertial measurement unit (IMU) three synchronized internal factors. With the rapid development of commercial GPS and IMU, through the LIDAR from the mobile platform (such as on the plane) to obtain high precision data has become possible and widely used.
The LIDAR system consists of a single beam narrowband 300mw Green Laser and a receiving system. The laser generates and emits a beam of light pulse, hit the object and reflected back, was finally received by the receiver. The receiver accurately measure the pulse propagation time from launch to be reflected back to the. Because of the light pulse travel at the speed of light, so the receiver always in the next pulse emitted before the received pulse is reflected back to the previous one. In view of the speed of light is known, the propagation time can be converted to the measurement of the distance.
According to the principle of radar measuring speed is between itself and the target frequency Doppler effect caused by relative motion. The radar target echo frequency and radar received different transmitting frequency, known as the difference between the Doppler frequency. One of the extraction from the Doppler frequency can be the main information between the radar and the target range rate. When the same space target and clutter interference exist in the resolution of the radar unit, among them Doppler frequency interference from the different clutter target detection and tracking using radar wave.