The Differences between Ultrasonic Radar Sensors, Millimeter Radar Wave Sensors, and Lidar Sensors

I Ultrasonic Radar Sensor
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Ultrasonic radar sensors are widely used sensing hardware in the automotive field, such as the reversing radar on our cars, which uses it.

Its principle of action is that the transmitter sends out ultrasonic waves, which are reflected when encountering obstacles and are received by the receiver, thus obtaining the specific distance between obstacles. However, the scattering angle of ultrasonic waves is large, not conducive to long-distance recovery of signals, so the working distance of the ultrasonic radar is not very far, between 0.1-3 meters with high accuracy. However, it should be noted that ultrasonic radar is susceptible to weather conditions, the propagation speed of different weather is different, and the speed of the car is also a factor affecting the accuracy.

Ⅱ Millimeter Wave Radar Sensor
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The wavelength of millimeter wave radar sensor is between 1mm-10mm, with strong penetrability, can easily penetrate plastic, paint and other materials. Therefore, millimeter wave radar sensors are often installed in the bumper, and even on the body side skeleton. It works by transmitting millimeter waves out, reflecting them when they encounter an object, and then being accepted by the reflector, which calculates the distance through the time difference.

Unlike ultrasonic radar, millimeter wave radar because of strong penetration, foggy days, dust, smoke and other environments have no effect, the only thing to pay attention to is the rainy days, will be affected by the slightest, but the overall performance is still better than ultrasonic radar. In addition, millimeter wave radar detection distance is also farther, up to 200 meters. Because of this, millimeter-wave radar is also a key part of the high-speed cruise distance-keeping function.
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However, millimeter-wave radar also has some small shortcomings, that is, in the detection of pedestrians such as reflective surface of small objects, millimeter-wave radar is easy to false alarms. For this problem, car companies have also done the corresponding “remedy”, such as through the combination of detection with high-precision camera.

Ⅲ Lidar Sensor
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The signal emitted by LIDAR sensor is not sound waves but laser beams. The system can determine a lot of information by comparing the signals reflected back from the target, such as target distance, orientation, height, speed and even shape and other parameters. In addition, LIDAR has a relatively long detection range, up to 500 meters in the automotive sector.

In addition to its long detection range, LIDAR is also characterized by its ability to detect lane lines. LIDAR relies on the unique intensity of the reflected light signal to distinguish lane lines. In terms of working principle, it is simpler and more secure.

However, the cost of LIDAR sensors is higher than that of millimeter wave radar sensors, which is why, at present, there is no large-scale use of this technology on the market.