Understanding the System Architecture of Onboard Cameras in Autonomous Driving

Understanding the System Architecture of Onboard Cameras in Autonomous Driving

Author / Ab宝

Editor / Ab宝

Produced by / Ab宝1990

Understanding the System Architecture of Onboard Cameras in Autonomous Driving

Explanation of the Internal Structure and Working Mechanism of Camera Modules:

Understanding the System Architecture of Onboard Cameras in Autonomous Driving

Lens: Gathers light and projects the scene onto the imaging medium; some use a single lens, while others require multiple layers of glass for better imaging.

Color Filter: The visible light spectrum seen by the human eye is limited, while the light spectrum that image sensors can recognize is broader. Therefore, a color filter is added to eliminate excess light, enabling the image sensor to capture the actual scene as seen by the human eye.

Image COMS Sensor Chip: This is the imaging medium that converts the image (light signal) projected by the lens onto its surface into an electrical signal.

PCB Substrate: Transmits the electrical signals from the image sensor to the backend. For onboard cameras, the circuit board will have more circuitry to convert parallel camera signals into serial transmission, enhancing anti-interference capabilities.

Understanding the System Architecture of Onboard Cameras in Autonomous Driving

The working principle of the camera module is that the lens converges light, then an IR filter removes unwanted infrared light. At this point, the analog signal enters the sensor COMS chip, which outputs a digital signal through AD conversion. Some setups include an ISP image processing chip at the camera end to process the signal before sending it to the host, while others rely on the built-in ISP chip on the host for image processing, improving heat dissipation and reducing radiation at the camera end.

Understanding the System Architecture of Onboard Cameras in Autonomous Driving

Onboard Camera Architecture:

Understanding the System Architecture of Onboard Cameras in Autonomous Driving

The structure of the onboard camera is shown in the above image. If placed outside the vehicle, a complete camera must be assembled. If it’s an in-car DVR, waterproofing is not a concern, and it can be assembled into the camera module shown above.

Understanding the System Architecture of Onboard Cameras in Autonomous Driving

The above image shows a common camera module used in cars. Aside from the outer aluminum shell, sealing ring, and lens, the interior consists of several simple layers of boards, usually including the sensor board, a small board for the image processor, and a serial board. The serial board is necessary because the output bus for camera sensors or ISP image data is often MIPI CSI standard, which is characterized by high speed but short transmission distances, otherwise signal integrity cannot be guaranteed.

Therefore, in vehicles, we need to convert it to a high-speed bus standard suitable for long-distance transmission in cars, such as GMSL. Consequently, the camera module typically includes a serial board for bus conversion. Additionally, coaxial cables can be used to power the module and transmit image data.

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https://mp.weixin.qq.com/s/FiW0S6PRjdFWW8eeCiJWxQ

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