Since its establishment in 2003, AUTOSAR (Automotive open system architecture) alliance has been committed to changing the design of on-board network and electronic control unit (ECU). AUTOSAR is an original equipment manufacturer (OEM) and its primary suppliers provide an industry standard method to design and develop ECUs located in modern vehicle centers. This standard will help reduce the generation of human errors in the design process and provide suppliers and manufacturers with a clear and machine-readable data format to exchange design information. This paper will discuss some expected suppliers of AUTOSAR adoption strategy Some basic terms and design methods are explained.

AUTOSAR alliance members include automotive OEMs and supporting ecosystems composed of parts and service suppliers. The purpose of the alliance is to create and establish a global open standard for automotive electrical / electronic (E / E) architecture. The standard provides support at the vehicle architecture level, enables OEM network designers to design and manage the complex relationship between vehicle functions, and also supports suppliers to define the details of independent ECU interfaces before manufacturing.

Why use AUTOSAR instead?

A modern luxury car may contain up to 100 ECUs, ranging from simple sensor interfaces to complex entertainment information and telematics units. There is a high risk of switching all of them to AUTOSAR methods and standards at one time, but such changes by original equipment manufacturers and primary suppliers will bring many benefits. It is expected that by 2020, all vehicles will have some AUTOSAR based ECUs, so the existence of this standard can not be ignored.

Some reasons and benefits of switching to AUTOSAR include:

Better reuse of electronic control units in new automotive platforms and Architectures

Better use of pre validated and tested software components (representing vehicle functions)

Reduce downstream design errors – an AUTOSAR approach allows functions to be defined and verified at the architecture level

Reduce overall hardware costs by improving network efficiency and function utilization

It can reduce the cost of overall network architecture analysis and design review

The use of a standardized data exchange format (autosarxml or arxml) improves communication between OEMs and primary suppliers

No matter whether the ECU needs to be redesigned or improved in the whole internal design cycle, switching to AUTOSAR can accelerate the design adjustment. For example, the workflow of the new tool, Or to help maintain compliance with iso26262 (conformity), which will change the work process. If we use AUTOSAR method, we can import it at the same time when changing the process. No matter how to implement the adjustment, the first design project of electronic control unit based on AUTOSAR takes longer than the existing / traditional design process, because designers need time to familiarize themselves with the new method. But then we can Bring results of cost saving and efficiency improvement. It is also possible to turn traditional ECU assets to AUTOSAR standards. By adopting the concept of “AUTOSAR wrapper”, important existing and proven electronic control unit application codes can be reused. This enables AUTOSAR packaging to be imported into other pure AUTOSAR ECUs. This will help reduce the risk of switching to AUTOSAR methods.

What is AUTOSAR?

In essence, AUTOSAR provides standard ECU interface definitions, enabling designers to specify reusable standardized software layers and components required in each Automotive ECU. The standard is not affected by hardware, which means that the application software and hardware platform are independent of each other. Application software developers can clearly explain the details of various vehicle functions in the application software without worrying about relevant software services and hardware interfaces. In the past, software and hardware were tightly integrated, so it was difficult to achieve portability and reusability (Figure 1).

Automotive open system architecture, improve vehicle network and ECU design

How to improve the architecture of Automobile Open System

Figure 1: separating application software from hardware.

Separating design from hardware decisions enables vehicle manufacturers / OEMs to design top-down according to the required vehicle functions. The concept of virtual functional bus (VFB) existing at this design time enables all software electronic control units to be interconnected and tested. This allows designers to focus on the application layer rather than the basic software infrastructure. By adopting virtual functional bus, application software components (SWC) is also independent of other application software components. The software components send output signals to the virtual function bus, and the virtual function bus transmits the information to the input port of the target component. AUTOSAR defines the input and output ports and the format of information exchange The abstracted method makes it possible to realize the interactive verification of all vehicle software functions and interfaces before defining the relevant hardware. Therefore, the design adjustment is much easier, and all functions are defined as software components on the virtual function bus (Figure 2).

Automotive open system architecture, improve vehicle network and ECU design

How to improve the architecture of Automobile Open System

Figure 2: testing software components on the virtual function bus.

Although the virtual functional bus does not provide information on how ECU is distributed and interconnected in real vehicles, it is a very useful test benchmark for architecture design time. Timing check and interface definition can be carried out for all signals in the vehicle.

Once the designer is satisfied with each function, these functions will be mapped or aggregated into a specific hardware electronic control unit. AUTOSAR supports the mapping and aggregation process of software components. A complex ECU may contain many software components, which can be organized in a hierarchical manner if necessary.

Automotive open system architecture, improve vehicle network and ECU design

How to improve the architecture of Automobile Open System

Figure 3: assigning software functions to real electronic control units.

AUTOSAR operating environment

Each ECU has a customized operating environment for it (RTE), which can be automatically created by supporting design tools. The actual communication between real electronic control units will be realized as a part of can or flex ray bus, and the operating environment is configured by generating tools to execute the communication path required to connect AUTOSAR components. The operating environment can effectively execute the communication and connection of virtual function bus and architecture design process Connect topology. Since AUTOSAR standard supports many different types of software components, the running environment must consider the limitations and changes of various software components.

Provide services for AUTOSAR components – basic software layer and operating system

Basic software (BSW) is a standardized software, which does not include vehicle application logic and electronic control unit functions, but provides hardware dependent and hardware independent services for the operating environment. The required services include memory services (NVRAM manager), network communication management service, diagnostic service and status management. When the AUTOSAR software components defined in the application layer require services, the task of the running environment is to complete the image on the real electronic control unit.

The operating environment does not provide any mechanism to obtain services from remote ECU, and AUTOSAR specification does not allow this. All service requirements must be met on the “local” electronic control unit. The basic operating system (OS or OSEK) running on the real electronic control unit does not know the AUTOSAR “runnable” concept. The operating system has a list of schedulable activities, which are managed by the scheduling algorithm.

About hardware

AUTOSAR layered software architecture can separate the application logic of hardware for reuse and portability. Running environment, operating system and microcontroller abstraction layer (MCAL), which provides access to physical ports and devices on the main microcontroller. The microcontroller abstraction layer is unique to each microcontroller, enabling the operating system and basic software to access devices such as digital input / output, analog-to-digital conversion, flash and EEPROM support. Figure 4 illustrates the relationship between different hardware and software layers in the AUTOSAR electronic control unit.

Automotive open system architecture, improve vehicle network and ECU design

How to improve the architecture of Automobile Open System

Figure 4: how components are assembled in a real electronic control unit.

Support new methods

Automobile OEM can operate the complete model of the whole network through a top-down AUTOSAR design method. AUTOSAR design tool allows a single ECU to be extracted, And in autosarxml (arxml) defines the connectivity and interface information. This interface definition will be transmitted to the primary supplier for further detailed design and implementation. Since the format has been standardized, the same definition can be distributed to several primary suppliers at the same time during public bidding. The advantage of standardized description is that any design ambiguity can be avoided in ECU description, and With the development of AUTOSAR standard, the possibility of misunderstanding is becoming smaller and smaller. Since this standard has nothing to do with hardware, it can make full use of the benefits brought by new industrial trends, such as in vehicle Ethernet, hybrid technology vehicle network (can / flex ray), heterogeneous multi-core platform and on-board gateway layout.

Want to try?

Some operators, including mentor graphics, have been able to provide an evaluation suite for AUTOSAR design. These kits include architecture design to a single ECU configuration. Mentor graphics also has its VSX tool kit and ECU Hardware development board supporting can, flex ray, Lin and Ethernet. These tools are based on eclipse and use the open source tool chain to carry out a series of design from source code to operation and implementation. Low risk investigation and AUTOSAR test are preferable to completely change the in vehicle ECU to AUTOSAR method at one time.

AUTOSAR provides predefined standard methods for on-board network and ECU design, and finds a way to enter each automobile OEM and primary organization. AUTOSAR standard provides opportunities to improve process and reuse components, but it also brings challenges to learn new ECU design processes and tools. Early adopters of AUTOSAR have been transferring this knowledge to mainstream design and resources, and there are many tools available for mass production on the market today. The adoption of AUTOSAR can also help operators meet the requirements of functional safety standard iso26262, because it supports a repeatable, well-defined and top-down design process.

Responsible editor: CT

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