Automotive Imaging Camera

In recent years, the enthusiasm of autonomous driving has brought people’s attention to vehicle camera imaging systems. Recently, the term “vehicle regulation level” has once again brought attention to car imaging systems. Some time ago, Black Sesame and Horizon released their own car-grade chips, and Mobileye and NVIDIA also have relevant car-related chips. For users, the car grade also means more safety and more mature technology. The camera imaging system functions as the main function in these chips. As shown below, the camera function in the car is rich and diverse. So what exactly is a car regulation level? What are the main car regulations related to imaging? What are the requirements for the imaging system? How to carry out related design development and certification for different functions? We hope to introduce these related content in a series of articles.

Main car regulations

First of all, it must be clarified that the car regulations are not a single standard specification, but a series of related (international) national standards. Due to the safety of the car, if relevant components and systems can be used in the car, and the car must finally pass the corresponding standards and specifications on the road. Some of these specifications are international norms such as the resumes of the United Nations or the International Standards Organization, and there may be differences in regional norms in different regions. For example, China, the United States, Europe, and Japan often have some national or local regulations. Even when national regulations are missing, some provinces currently have different regulations for ADAS and autonomous driving. This article mainly introduces international standards, others are introduced later. In terms of international regulations, imaging chips are generally mentioned, and the common ones refer to the car regulations in the following figure (this is the main part but not comprehensive, in fact, there are many car-related specifications). There is no description of some specifications related to the image quality of the imaging system, but the development of imaging systems must also follow the corresponding specifications, so we first introduce this part.

The top ISO16949 is an internationally accepted quality system for the automotive industry. This specification applies only to auto OEMs and their direct component manufacturers. However, the authentication method is not complete, and then VDA6.3 is used to supplement the authentication process.

Then there is ISO 26262, which is also the most popular specification at present. The technical and management requirements for the safety life cycle of automotive electronic safety systems from development to use are specified from the perspective of functional safety. According to different standards, the products are divided into four levels: ASIL-A, ASIL-B, ASIL-C, and ASIL-D. This specification not only regulates the hardware itself, but also regulates the design, development, and testing of software. It will even affect the choice of operating system and three-party algorithms. We will also analyze the content related to imaging development in this protocol in detail later.

This series of specifications is the International Automotive Electronics Council (Automotive Electronics Council (AEC)) as a vehicle certification reliability verification standard in different environments, including AEC-Q100 (Integrated Circuit IC), AEC-Q101 (Discrete Components), AEC-Q200 (passive component). And AEC-Q102 (discrete photoelectric LED), AEC-Q104 (multi-chip components) are the newer automotive electronic specifications in the near future. Under its specifications, different levels of requirements are imposed on the device for different working environments such as high and low temperature and electromagnetic environment. For example, AEC-Q100 is divided into 5 levels, and the most basic division criterion is temperature range. among them,

Class 0 is the highest (-40 ° C to + 150 ° C),

Level 1 is -40 ° C to + 125 ° C,

Level 2 is -40 ° C to + 105 ° C (which is more common),

Class 4 (0 ° C to + 70 ° C).

Relatively speaking, AEC-Q100 is more device-specific, while ISO 16750 is for testing of subsystems and modules, including
Electrical load (16750-2), mechanical load (16750-3), climate load (16750-4), chemical load (16750-5)

IECQ AQP mainly regulates vehicle verification, quality and production processes during the production of vehicles.

Eliminating the LED flicker below 60Hz is an important requirement for automotive sensors. The sub pixel scheme used by Sony’s automotive sensors has good performance in LFM.

In the past, for device manufacturers to enter the vehicle field and enter the Tier1 automotive electronics manufacturers’ supply chain, two tickets must be obtained. The first is the AEC-Q100 (Integrated Circuit IC) promoted by the North American automotive industry. ), AEC-Q101 (discrete component), AEC-Q102 (discrete optoelectronic LED), AEC-Q104 (multi-chip component), AEC-Q200 (passive component) reliability standards; for the second ticket, it must meet zero failure ( Zero Defect) supply chain quality management standard ISO / IATF 16949 (Quality Management System). But now as cars become more and more intelligent, different levels of ISO 26262 become even more important.

Unlike the protocols and specifications mentioned above, the two specifications of IEEEP2020 and ISO16505 are standards related to image quality on automobiles. According to the above division method, the two standards for image quality should be divided as follows.

Refer to the following figure according to the correlation with the imaging system.

Now on to the topic, introduce the differences between these two and image quality related protocols.

1 IEEEP2020 Standard for Automotive System Image Quality

2 ISO 16505 Road vehicles-Ergonomic and performance aspects of Camera Monitor Systems-Requirements and testprocedures

There are two main applications for cameras in cars: one is for human vision applications, which is to show people. Such as electronic rearview mirrors, surround view systems, etc. Another application is computer vision applications. Such as automatic driving, automatic parking and so on.

The IEEEP2020 hopes that the specifications are tests and issues related to the image quality of all cameras in the car. Both human vision applications and computer vision applications are in its category. And its main specification is the image quality of the camera imaging system.

ISO16505 is mainly a specification for the quality of related monitoring systems visible to the human eye on the vehicle, and systems that are not visible to the human eye are not mandatory. The main test object is the CMS (camera monitor system) system, and this system includes electronic rear-view mirrors and electronic surround-view systems. In the strict sense, this protocol regulates the (camera + display) system. However, many of these are indeed related to the camera image quality, and if you pay attention to the progress of P2020, you will find that many of the issues considered and the contributors suggest that the test cards and calculation methods are consistent with ISO16505.

From the test range, both include these basic test items: resolution, brightness and contrast, Sharpnees, depth of field, uniformity, color reproducibility, Artefacts, geometric distortion, frame rate delay, etc

ISO16505 actually includes many detailed tests and standards related to rear-view mirror display. The test environment also considers different options for extracting data from the display or system. In terms of implementability, ISO16505 is currently very detailed, but what needs to be distinguished is the entire system targeted in the 16505 test. For imaging it is necessary to subdivide the criteria into image quality again. The following figure is a typical test system of 1605. We can see that 5 of them are using a reference camera to capture the image output by the system and then analyze it. For image quality, it is more appropriate to obtain images for analysis before the output display system. We will discuss this in more detail in a later article.

But P2020 proposes more tests for computer vision and development. Such as high dynamic range, Dark Current, Veilingglare and so on. However, P2020 is currently only a white paper phase, which only describes the problems that need to be solved and the protocols corresponding to other test corresponding items that can be referred to.

In this article, we simply analyze the vehicle regulation protocols related to the imaging system and image quality. There may be incomplete or incomplete understanding. Welcome everyone to discuss it together. The specific protocol and test items will be explained in a later article. Welcome everyone’s continuous attention and suggestions.