基于AUTOSAR的汽车FlexRay网络通信故障检测与管理

Fault detection and management for automotive FlexRay network communication based on AUTOSAR

针对汽车网络安全性、可靠性等通信要求,参照AUTOSAR网络管理规范,提出一种基于故障检测的FlexRay网络通信管理方法,建立了节点内部网络通信管理状态转换模型,设计了Errorcheck状态下的分布式故障检测机制,给出了该机制下FlexRay网络参数及网络管理参数的计算方法,实现了网络节点状态实时监控和协同休眠功能。VectorCANoe中的仿真试验结果表明:该方法不仅能够实时在线管理FlexRay网络通信,实现高效的节点故障检测,而且可以有效降低网络通信管理带宽消耗约为5%。该方法为建立高可靠的车载网络通信管理系统提供了参考。

During the past few decades, more and more hydraulic components in vehicles have been replaced by electronic control units （ECU）. The increasing number of ECUs leads to the larger demands for real-time and high-speed communication between ECUs. As a result, communication network has become an inevitable trend in vehicles. Compared with the traditional controller area network （CAN） bus, FlexRay bus has great advantages in transmission efficiency, reliability and flexibility. Since it can meet the future requirements of network communication between ECUs, it has been applied to the power system, chassis system and X-by-wire system in some vehicles. However, how to guarantee the safety and reliability of FlexRay network communication has become an important problem. AUTOSAR NM （automotive open system architecture network management） possesses the functions of the state real-time monitoring and the cooperative sleep of network nodes, which are suitable for the vehicular FlexRay network management. AUTOSAR FlexRay NM mainly consists of 3 basic modes： bus sleep mode, synchronization mode and network mode. Based on the AUTOSAR NM, a network communication management method with fault detection function is proposed and designed. First, a FlexRay network of an automotive chassis and AUTOSAR NM is described. Second, the network internal nodes’ state transition model of network communication management is established. For this model, besides normal operation state, repeating message state and state of preparing for sleep in AUTOSAR NM, a state of Error check is introduced to identify the communication faults of network nodes. Third, a distributed fault detection state mechanism is designed for the Error check state. Finally, the processing mechanism to the fault by the application layer is also given. Through the cooperation between the NM message and a variety of timers, the nodes can easily make sure whether the communication of suspected nodes works well. Furthermore, to reduce the bandwidth consumption of the previous NM, the calculation method for the key parameters is taken into consideration. The NM message is incorporated with the user messages, and then a mixed frame structure is adopted. The parameters like FlexRay static slot and the values of all NM timers are designed. At last, the experiments in Vector CANoe, which is a specialsoftware for automotive network application, are carried out to validate the proposed NM method in the paper. In the experiments of node communication failure, our NM with Error check has shorter response time to the node communication failures in the network than the traditional OSEK NM and the response time is also steadier. Besides, the practice of the network cooperative sleep is verified. In the other experiments for the bandwidth consumption, the equations of the consumption rate are presented, and the results show that the bandwidth consumption is close to zero because of the mixed structure while the bandwidth consumption of other methods is more than 5%. When the number of nodes is a constant, the bandwidth consumption of the previous NM decreases by 5% with the increase in the number of user messages. So the NM with Error check function proposed in the paper can be more suitable for the real-time application in the vehicular communication. In the future, the state transition model and the fault detection mechanism of network communication management will be further optimized.