Advantages and disadvantages of millimeter wave radar and lidar

Millimeter-wave radar has the advantages of moderate cost and strong identification ability, but the disadvantage is small detectable angle. The advantage of lidar is small divergence angle and concentrated energy, but the disadvantage is high cost at present.

Choosing the right sensor group for self-driving cars is a delicate task, because a series of factors from reliability to cost need to be balanced, so that companies can determine the best point and choose the best sensor group. The basic scheme of ADAS in the early days was to configure a millimeter wave radar at the front of the car, a camera under the driver's windshield and an ultrasonic radar at the rear. These three kinds of sensing devices are cheap and mature in technology, and can realize most functions of L2 level.

The function of radar

The working principle of millimeter-wave radar is to detect and perceive the surrounding objects by transmitting radio signals, and then recover the scattered reflected signals, and then get the information of reflection points through algorithms, and then get the relative distance, relative speed, angle, moving direction and so on. Between cars and other objects. The biggest advantage of millimeter wave is that it ignores the weather, has strong ability to penetrate fog and smoke, and is less affected by environmental factors, so it can be used in daily occasions.

Lidar can know the relative position and speed of an object by emitting a laser beam and then receiving the target echo and comparing it with the emitted signal. The advantages of lidar are high resolution and precision. Compared with millimeter-wave radar with the accuracy of 10CM, the accuracy of lidar can be easily reduced to millimeter level, and 3D graphics of all surrounding objects can be established in an understatement.