Research On Certain Key Thoeries Of CAN Protocol For Automotive Network

Safety,energy conservation,environmental protection and automotive intelligentizing are the driving factors of automotive electronics development. Networked vehicle becomes the main trend of vehicle field in recent years. Automotive network is the platform of automotive electrical system and integration design, and also the key of automotive intelligentizing. Researches on automotive network theories based on CAN protocol have the aim of interlinking automotive electrical systems by the work, realizing the high efficiency integration of automotive electric controlling system,real-time cooperation and dependable comprehensive controlling. These researches have profound significances on technology and economy.Till now CAN have already become the most successful standard of automotive network. But concerning the complicated vehicle utilization environment, there remains demanding on security,real-time,reliability and bandwidth resources utilization ability of CAN protocol network. Besides vehicle high-electromagnetism interference environment and network fault, the problems need to coped with that how to efficiently integrate the network, how to design scheduling algorithm to improve real-time and flexible ability of various requirement, how to ensure dependability by real time analysis, how to improve bandwidth resource utilization,how to carry out visual software of analysis still exist.In this thesis, the research of certain key theories of CAN protocol for automotive network is developed and the engineering applications of those theories are explored. The works are as follows:1. Automotive network development is project of system engineering, relating factors including node design, system integration, communication, time synchronization, function cooperation and cost. In this thesis, after analyzing integrated theories of fieldbus, the integration policy of automotive integrated network based on CAN protocol is proposed, and'V'development model is improved for automotive network system.2. For higher flexible, more efficient and soft real time of automotive body electronic network system, comparing of single-signal frame and group-signal frame with RM scheduling algorithm is researched, and flexible factor is proposed to improve the flaw of RMA. The contrast analysis and simulation show that the group-signal frame is superior in flexibility, bandwidth utilizing margin and real time.3. For hard real time, closed loop time trigger and fault tolerate of automotive power drive network system, time-triggered CAN (TTCAN) is analyzed to instead of CAN that is not good at cooperating, determinism and fault tolerate because of inability to time trigger. Then schedule based AL scheduling algorithm is proposed to construct the system matrix of TTCAN, and the worst jitter criterion is proposed to apply to time trigger service. The contrast result shows TTCAN scheme is superior to CAN scheme for periodical messages in determinism, real time, fault tolerate and bandwidth resource utilization.4. For various applications of automotive whole networks, two schemes that single-TTCAN network and CAN-TTCAN based two-network network, are respectively researched. Mixed scheduling algorithm and analysis theories are proposed for the front, and two-network scheduling policy and relating analysis scheme are proposed for the latter. The analysis results show that the single-TTCAN network is superior in schedule ability, utilization, integration, and two-network network is superior in collision rate and cost.5. Aiming at imbalance question that CAN protocol is not determinate but flexible, TTCAN is not flexible but determinate, in this thesis, flexible time trigger CAN (FTTCAN) is researched, dynamic programming conception is imported. And scheduling plicy based on programming is designed. Analysis and experiment results show the scheme is not only real time but also flexible and determinate.6. for the question that CAN protocol based schedule algorithm and analyzing theory are too complicated to apply, visual technology is adopted to design visual analysis software, and single-step-recurrence relation (SSRR) expressions are deduced to simple the complicacy of RMA recurrence algorithm. And because automotive integration-message watch-control system implements various messages sampling, computing and interchanging, sporadic traditional system cannot support the reqiuement. In the thesis a distributing configuration based on CAN protocol is designed, DM scheduling algorithm is used to schedule network and analyzed by the designed analysis software. And an experiment and test system is designed according to V development model. The simulation and experiment results testify the superiority of the scheme.