01

challenge


With the continuous growth of automobile sales and the rapid development of autonomous driving technology, the automotive industry has increasingly higher requirements for safety and automation. In addition, intelligent technology gradually enters people's lives, making the design of automotive electronics more difficult.


Complex system design


Automobiles are becoming more and more electronic and intelligent, which brings great challenges to the design of the system architecture. The most important part is that the number of electronic control units (ECUs), which are regarded as the "brains" of automobiles, is increasing day by day, all over the engine management system (EMS), automatic transmission control unit (TCU), body control module (BCM) , Body Electronic Stability Control System (ESP), Battery Management System (BMS) and other components. According to surveys, mid-range cars are equipped with more than a dozen ECUs. High-end cars are often equipped with dozens or even hundreds of ECUs. Combine them to form a complex computer network. The traditional document-based system design (DBSE) is not very readable for this complex design, which is not conducive to product iteration.


Huge amount of code


The continuous advancement of automobile intelligence has made the amount of code of automobile electronic software more and more huge. At present, the amount of code for advanced smart cars has exceeded 200 million lines, and it is expected that the amount of code for autonomous driving will exceed 1 billion lines in the future. If such a large amount of code is purely handwritten by many engineers, it will not only be inefficient, the quality of the code will not be effectively guaranteed, and it will also bring about security problems.


Test verification is restricted


Due to the large deployment of ECUs with various functions, many problems have been brought about in testing and verification, such as the parallel development of software and hardware. When the software development process starts, the required hardware environment is often not available. After software development is completed, testing and verification cannot be performed quickly, and the hardware supply problem needs to be resolved urgently. The running speed of the real ECU is fixed, and it takes a long time to run for complex functional tests, and the test efficiency is not high.


Need to integrate as soon as possible


Huge automotive electronic systems are often completed by different developers or departments. There may be problems such as understanding deviations in the design and interface inadaptability. If the integration verification cannot be carried out as soon as possible, it will be very complicated when the final integration and debugging are carried out. And it takes time to work, and even delays the construction period.


02

solution


In order to solve a series of needs in the automotive industry, such as design and simulation, Zhejiang Dijie Software Technology Co., Ltd. has developed an integrated solution based on MBSE, using purely independent research and development software, which can meet the entire automotive electronic system from demand, design to simulation verification. The life cycle is autonomous and controllable. Here, the charging and discharging scenario of a hybrid car battery is taken as an example to describe the entire integrated solution.



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▲Figure-1: Model-based System Engineering (MBSE)


System modeling tool SysModeler based on SysML


SysModeler is a tool for system design and analysis. It uses the Sys ML language to model the system, so that system design engineers do not need to pay attention to the details of software implementation, but pay more attention to high-level function division, structural decomposition, behavior specifications and requirements analysis. As shown in the figure, the requirements are analyzed in detail according to the charging and discharging scenarios of hybrid car batteries, and the creation of use case diagrams and state machine diagrams.


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▲Figure-2: Battery demand activity diagram created by SysModeler


ModelCoder, a code generation tool for formal verification


ModelCoder is a tool for software design and development, which visually models algorithms and control logic, and generates highly reliable codes that have undergone formal verification. The development of traditional automobile functional modules originally took several months to write code, but on ModelCoder, the model automatically generates code. You only need to build the algorithm and control logic according to the requirements, and the code can be generated with one key, which saves the most. The development cost. The figure shows the decomposition of battery charge and discharge control logic modules and battery model requirements in hybrid vehicles based on SysModeler. Natural language is described as a model language to implement control algorithms, perform MIL testing through model simulation, and finally generate code.


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▲Figure-3: Battery model constructed by ModelCoder


Full digital real-time simulation software SkyEye


SkyEye is a software testing and simulation tool. The full name of SkyEye in Chinese is Tianmu all-digital real-time simulation software. It is a hardware behavioral simulation platform based on visual modeling. The all-digital simulation platform can perform behavior-level real-time simulation of ECUs and external devices, and can simulate and test various embedded programs without hardware, which can effectively solve the problem of insufficient hardware environment supply. At the same time, by using the dynamic binary translation technology based on LLVM, the virtual ECU's operating speed is much higher than the real speed, and the test efficiency is improved. As shown in the figure, build a virtual simulation platform for the battery charge and discharge control model according to the hardware requirements, simulate the hardware CPU to run the control logic program generated by ModelCoder through the platform, and control the vehicle battery model to charge and discharge through the system simulation bus and display the battery voltage.



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▲Figure-4: Co-simulation of SkyEye and battery model


SkyEye is a software testing and simulation tool. The full name of SkyEye in Chinese is Tianmu all-digital real-time simulation software. It is a hardware behavioral simulation platform based on visual modeling. The all-digital simulation platform can perform behavior-level real-time simulation of ECUs and external devices, and can simulate and test various embedded programs without hardware, which can effectively solve the problem of insufficient hardware environment supply. At the same time, by using the dynamic binary translation technology based on LLVM, the virtual ECU's operating speed is much higher than the real speed, and the test efficiency is improved. As shown in the figure, build a virtual simulation platform for the battery charge and discharge control model according to the hardware requirements, simulate the hardware CPU to run the control logic program generated by ModelCoder through the platform, and control the vehicle battery model to charge and discharge through the system simulation bus and display the battery voltage.


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▲Figure-5: SkyEye and Jenkins continuous integration process


The integration of SkyEye and Jenkins can help the team work more efficiently. Continuously integrate the scattered modules and use the simulation environment of SkyEye all-digital simulation software to conduct automated simulation tests, effectively ensuring the quality of the software and improving work efficiency.


03

Summarize


In order to cope with the current challenges of the rapid increase in product complexity in the automotive industry, the MBSE design method is more able to adapt to the increasingly complex system design needs. The MBSE method can reduce costs and shorten the project cycle. It can be implemented in Ford and has gradually been recognized by the automotive industry. Integrated MBSE is a systematic project, and there are many new technologies worth exploring and researching. Dijie Software is making continuous progress in MBSE theoretical research and product development, and has achieved some results. The full range of MBSE product chain in the future is worth looking forward to.

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