The Development Of Fault Diagnosis Software On Application Layer Based On Stateflow Models

Fault diagnosis function has been became a necessary feature in vehicle safety management fields. The hybrid electric bus tire pressure monitor system is the composition of the hybrid electric bus and tire pressure monitor system. Due to its intelligent and efficient monitoring of the diagnosis, it has been widely recognized in the hybrid electric bus. And its software development is becoming more and more important. In this paper, we developed the monitoring controller software based on the Stateflow model, and summarized a method in model-based development.Firstly, Design of hybrid bus tire pressure monitoring system controller. The system controller will get information of the tire pressure status by logic operation and transform it into a fault message frame and then transmit to the vehicle controller. It analyses the bus protocol file and collects and sorts fault diagnosis data in relevant subsystems on design, production and testing. The Bus communication protocol commonly refers to J1939 protocol, from the lowest physical layer to the application layer, we find out the terms that will be used in the development and design and analyze the logical relations and the possible implementation. The model implementation program is designed on the basis of the characteristics of the way of model implementation. Meanwhile, HEV and conventional bus can differentiate from each other on fault messaging by activating reserved numbers in the control domain. The logic will be realized through the fault diagnosis logic on application layer and finally be embodied in the form of messages by transmitting the faults to the CAN bus simultaneously.Secondly, on the basis of the above analysis and the corresponding implementation process, main variables and structures that used in the program will be defined and the custom code functions that attached to the Stateflow models can directly complete some of the defining in file h. Then, the software will be divided into several functional models and one certain model will be detailed and assist in realizing the final goal.Finally, in the process of development, the models should be developed according to its functions on the basis of J1939-73 protocol file. In the input module, the corresponding data are input through the interface of Sateflow and Simulink; According to the requirements of the design, the input data is a six dimensional array which represents the current value of the six tires' pressure; in the detection module, current barometric pressure is compared with the reference pressure value so as to define the current state of the environment and transfer it to the corresponding fault parameters; in the data-frame module, the current fault position signal and fault type signal will be programmed into fault domain signals in corresponding ID; while in the transmitting module, messages are transmitted to the CAN bus on time or on request. Finally, all the sub-modules will be integrated according to the logic and execution sequence of the software and thus the system fault diagnosis model is formed.As for the verification of the model and the software, we verify the reliability of the model and the performability of the generated code respectively. Compared with the simulation period, the result of the verification of the model and the software meet the requirements, and it proves that the model is correct and timely in fault diagnosis.