ADAS system sensor layout location and method

With the advancement of technology, autonomous driving technology has gradually become a hot topic. Self-driving cars are classified as Level 5 autonomous driving in the SAEJ3016 autonomous driving level, using a variety of sensors, such as ultrasonic radar, millimeter wave radar, front-view camera, laser radar, etc. However, the placement and method of these sensors have a crucial impact on detection performance. This article will explore the placement and method of ADAS system sensors.

ADAS uses sensors to sense the surrounding environment in real time while the car is driving, collect data, perceive and fuse, and make decisions based on the perceived data, and finally control the vehicle and warn the driver. The placement and method of sensors have a crucial impact on the performance of the ADAS system.

1 front camera

The forward-looking camera is one of the indispensable sensors in the ADAS system, which can obtain rich environmental information including object color, shape, material, etc. At present, the forward-looking cameras on mass-produced self-driving cars are mainly single, dual and three-eye. Among them, the forward-looking smart camera is often used in medium and long-distance scenes, and can identify clear lane lines, traffic signs, obstacles and pedestrians. However, the forward-looking camera is very sensitive to conditions such as lighting and weather, and requires complex algorithm support, and has relatively high requirements for the processor. The forward-looking camera is installed on the front windshield with a viewing angle of about 45°. The binocular ranging function will be better, but the cost is 50% higher than that of a single eye.

2mm wave radar

Millimeter-wave radar is another important sensor in ADAS systems. There are two main types of radar: 24GHz radar for short and medium range measurement and 77GHz radar for long range measurement. Millimeter-wave radar can effectively extract depth of field and speed information, identify obstacles, and has a certain ability to penetrate fog, smoke and dust. However, in the case of complex environmental obstacles, since millimeter waves rely on sound waves for positioning, the sound waves are diffusely reflected, resulting in a relatively high missed detection rate and error rate. Therefore, in the layout of millimeter-wave radars, factors such as the orientation and height of the sensor need to be considered to maximize its perception performance. Millimeter-wave radars are usually installed on the front face, front bumper, and both sides of the rear bumper of the car.

For example, installing a forward-facing millimeter-wave radar on the front bumper of a vehicle and four corner millimeter-wave radars installed at the four corners can achieve a balance between performance and cost.

3. Ultrasonic radar

Ultrasonic radar is mainly used in short-distance scenarios, sending ultrasonic waves and receiving reflected ultrasonic signals, and sending the detection results to the controller. Ultrasonic waves consume energy slowly, have strong penetration, and the distance measurement method is simple and low cost. However, there are certain limitations in measuring distance at very high speeds. When a car is driving at high speed, the use of ultrasonic distance measurement cannot keep up with the real-time changes in the distance between cars, and the error is large. On-board ultrasonic radars are generally installed around the body of the car.

For example, holes are drilled on both sides of the front and rear bumpers for installation, leaving only circle marks of the holes.

4. LiDAR

LiDAR is an important sensor in ADAS systems, with advantages such as high precision, high resolution and long-distance ranging. LiDAR emits laser pulses to the target and measures the time of the return pulse to calculate the distance, which can build a three-dimensional point cloud map around the vehicle in real time. However, LiDAR is greatly affected by ambient lighting, weather conditions, etc., and is expensive. LiDAR is usually installed on the roof, front bumper or front face of the vehicle (such as the front grille). Such an installation position can provide a high field of view and all-round environmental perception capabilities.

For example, in order to enhance the overall beauty of the front face, the laser radar can be deployed under the two sides of the headlights.

Future development trend of ADAS sensors

With the continuous development of autonomous driving technology, the location and method of sensor layout will continue to be optimized and innovated. In the future, sensors will develop in the direction of miniaturization, integration, and low power consumption to meet the lightweight, energy-saving and environmental protection requirements of autonomous driving vehicles. In addition, the layout of sensors will be more flexible and diverse to meet the needs of different scenarios and environments. For example, designs such as flip sensors and retractable sensors will greatly improve the adaptability and reliability of sensors.

In short, the placement and method of ADAS system sensors are crucial to the safety and intelligence of self-driving cars. In the future, the placement and method of sensors will continue to innovate and optimize, bringing a safer and smarter travel experience to self-driving cars.