Many car advertisements will show such a picture: when the car is about to hit an obstacle violently, the anti-collision warning function equipped with the car stops driving at the last moment, protecting the lives of the young and old in the car.
In recent years, automobile safety performance has become the main focus of many manufacturers' advertisements, which confirms the improvement of safety's status in the current consumers' car selection indicators. In fact, before a new car is introduced to the public, every component must be thoroughly and systematically tested to ensure sufficient safety.
The safety of automobiles is an old-fashioned topic. In the past 100 years, automobile developers have made remarkable progress, from purely mechanical to electronic intervention, and to the current situation of "software-defined automobiles". Embedded systems combining software and hardware have become the backbone of the automobile industry. Say the use of every car component depends on software.
Automotive software needs to be deployed in the electronic control unit (Electronic Control Unit, ECU). As an embedded system on a semiconductor chip, the automotive ECU plays a vital role in the control of various components: whether it is engine control or braking These necessary functions, as well as security functions such as airbags and electronic locks, all require the intervention of the ECU. ECU is undoubtedly the core component of car safety.
1. How to test the ECU?
According to the report, the number of ECUs equipped in automobiles will exceed 100 in 2020. How to conduct comprehensive and systematic testing of these increasingly complex ECUs is a problem that every automaker must face.
In the traditional V-shaped development model of an automobile, each new stage must be completed only if the previous stage has been completed. The original equipment manufacturer (Original Equipment Manufacturer, OEM) builds the framework according to the specified requirements, the relevant software is provided by the supplier, and the final integration and acceptance test is still completed by the OEM. In order to ensure that each component has undergone strict safety and reliability testing and verification, the testing time will be continuously extended, and the overall feedback time of the development cycle will also be delayed.
In a regular software development cycle, data stored in hexadecimal format often needs to be circulated through multiple teams, and if other suppliers are involved in collaboration, the overall development cycle will be dragged out longer. At the same time, with the continuous innovation of vehicle functions and designs, each new development will lead to easier testing of ECUs. Expensive hardware testing costs and limited engineering workload are the most constrained reasons for OEMs.
In order to keep pace with the times in the fierce market competition, shorten the delivery cycle and complete the delivery efficiently while ensuring safety, OEMs must adopt additional testing methods.
2. Digital twin: make ECU "lifelike" in the digital environment
Building a virtual ECU model of digital twins of body parts and related mechanisms through simulation, and completing troubleshooting and proof of concept at an early stage have become the key to improving the efficiency of automotive electronics development.
Compared with real hardware, virtual ECU has the following advantages:
- The number is almost unlimited and the construction speed is fast. Software personnel are not limited by the number of hardware and the hardware development cycle, and can develop and test software at any time;
- It has very strong observability, and can observe and modify memory variables and even hardware status at any time, bringing huge efficiency improvements to measurement and calibration (may support automatic calibration);
- Support automated testing without human intervention.
However, as an embedded system, ECU is bound to be accompanied by a variety of processor types and peripheral buses. How to quickly and correctly complete simulation modeling and keep its operating performance in line with the real-time requirements of automotive electronic systems is a new challenge.
3. Domestically produced simulation software that meets the needs
Tianmu all-digital real-time simulation software SkyEye, as a hardware behavior-level simulation platform based on visual modeling, can provide a virtualized operating environment for embedded software required by automotive ECUs. Developers and testers can develop software on this virtual operating environment , software testing and software verification activities. From small chips to large systems, SkyEye can simulate them.
At present, the processors and peripherals simulated by SkyEye have covered most of the processors used in automotive ECUs, such as MPC5554 and Tricore series.
Applying SkyEye-based virtual ECU, engineers can:
- No need to care about the cumbersome connection relationship of real cables, the project is built once and can be continuously reused;
- It has the simulation ability of real CAN bus and INCA hardware, and supports almost unlimited number of simulation hardware;
- Support the operation of OS and application programs that conform to the AUTOSAR protocol;
- Integrate the original calibration host computer software, and connect the Simulink model to simulate real data.
The overall design framework of the virtual ECU is shown in the figure below:
In addition to significantly reducing test time and costs, virtual ECUs also provide engineers with various functions during the development process. With the most real feedback from the consumer market, the value of commercial operation of autonomous driving revealed, and the requirements of the vehicle electrical and electronic architecture for the Internet of Vehicles under 5G technology, the virtual ECU is a key driving factor for the team to test and verify without additional hardware. It has undoubtedly become an accelerator driving the development of automotive software.