Influence of Domain Controller Development on Harness Design

The concept of domain controller was first put forward by Tierl. It appeared to solve the problem of information security and ECU bottleneck. Because of its powerful hardware computing capability and rich software interface support, domain controller concentrated more core functional modules in the domain controller, which greatly improved the functional integration. This paper briefly introduces the characteristics, classification and influence of domain controller on wire harness.  

With the evolution of automotive E/E architecture and the increasing automotive electronic functions, the trunk of wiring harness becomes thicker and thicker, with more and more branches, and the volume of wiring loom becomes larger and larger, and the quality of wiring harness will also increase. In order to simplify the laying area of automotive wiring harness, reduce the quality of wiring harness, and meet the requirements of electrical appliances, domain controllers will be widely used in automobiles in the future.

1 The Development of Domain Controller

The so-called "domain" means that the automotive electronic system is divided into several functional blocks according to their functions. The internal system architecture of each functional module is led by the domain controller, and communication buses such as CAN and FlexRay can still be used for the interconnection of the systems in each domain. However, the communication between different domains requires Ethernet with higher transmission to undertake the task of information exchange for the backbone network. For the specific division of functional domains, different OEMs will have their own electrical architecture design concepts. In each functional domain, the control domain is at the absolute center, which requires powerful processing power, super-high real-time performance and a large number of communication peripherals.

In the development process of controller, the automotive electronic architecture can be divided into three stages, namely, the stage centered on functional module controller, the stage of domain controller and the stage of integrated central computer. Eventually, the car will become an unmanned vehicle with a supercomputer.

2 The Characteristics and Classification of Domain Controllers

According to the division of electrical modules and functions, the general vehicle electronic architecture can be divided into five domains: driver assistance/automatic driving domain, intelligent cockpit control domain, body control domain, chassis domain and powertrain domain. Among them, the driving assistance/automatic driving domain, intelligent cockpit domain and body domain are the key core points of differentiated competition between automobile enterprises in the future, which can realize the separation of software and hardware, thus realizing the profitability of software.

The domain controller stage is a service-oriented architecture with Ethernet as the backbone network. Centralization according to functions can accelerate the separation of software and hardware and save the cost of the whole vehicle electrical architecture. The specific advantages are as follows.

1) Reduce the redundancy of internal calculation force, avoid the expansion of ECU number, and reduce the total demand of design calculation force.

2) The traditional distributed architecture is difficult to realize real-time interaction, while the centralized architecture can realize unified interaction and realize vehicle function coordination.

3) After centralized architecture, the wiring harness is shortened and the whole vehicle quality is lightened.

3 Influence of Domain Controller on Harness

With the continuous increase of the electrical functions of the whole vehicle, the laying area and the quality of the wiring harness are facing great challenges, and the increasing integration of modules and the continuous improvement of communication ability are undoubtedly a way to send carbon in the snow for the low-voltage wiring harness of the whole vehicle. The influence of domain control on wiring harness is expounded through the following points.

1. Integration of Functions

The main reason why the laying area of the low-voltage wiring harness of the whole vehicle will continue to increase is that the connection between modules cannot be completely realized by CAN, and a large number of physical hard wires are needed as signal wires for reciprocating transmission, which will lead to the increase of wiring harness circuits, the diameter of wiring harness and the cost of wiring harness materials.

According to the architecture design of the functional domain, many functions can be set as one functional domain. For example, modules such as instrument controller, T-box and entertainment host can be merged and named as cockpit domain. The information exchange among modules can be completed inside the controller, and the instrument can transmit data to the display screen in a faster way (power line+video line), thus greatly reducing the amount of wires, not only reducing the burden of wiring harness, but also reducing the number and number of modules.

2. Domain Controlled Distribution

In order to reduce the cost of the controller and the quality of the whole vehicle, integration needs to effectively divide all the functional devices from the front part, the middle part and the rear area, such as the rear brake light, the rear position lamp, the rear door lock and the double struts, which are connected to a general controller. The body domain controller has gradually transitioned from the decentralized functional combination to the big controller that integrates all the basic driving, key functions, lights, doors, windows and so on of the body electronics.

Then, according to the functions and positions of the whole vehicle electrical appliances, the domain controller can be arranged in a relatively moderate position, which can not only meet the electrical performance requirements of the domain controller itself, but also be compatible with the corresponding electrical appliance functional connections.

3. Improvement of Transmission Rate

On the premise that the number of electric appliances in the whole vehicle is increasing and the information interaction is growing geometrically, the traditional wire harness transmission signal can't meet the information interaction demand at all, so the communication speed of the vehicle network must be improved accordingly. From the traditional LIN and CAN to FlexRay bus and Ethernet, its transmission rate is constantly setting a new record. Perhaps at some stage in the future, the low-voltage wiring harness of the whole vehicle will evolve into a new construction, that is, the power line and signal line, and the flexible circuit device will be born.

4 Concluding Remarks

Throughout the development of the whole automobile industry, the information flow brought by intelligent networking has been increasing greatly, gradually changing from traditional car-making to architecture and software-defined car. In addition, the high integration of control unit and the rapid increase of information interaction rate will surely lay a solid foundation for the lightweight and automatic assembly of wiring harness. It is believed that with the trend that domain controllers are constantly entering the vehicle network system, the automotive electronic system is bound to undergo great changes from the inside out.