Research On Scheduling Algorithm Of Dual-Trigger CAN Bus Based On Markov Chain

CAN bus,that is,controller LAN is a kind of field bus.Its communication protocol adopts short frame data and multi-master serial communication,which has advantages of simple structure,high reliability,strong anti-interference and error detection ability,low cost and so on,It provides extremely effective support for distributed network control.However,since CAN bus adopts event triggering and static fixed priority allocation mechanism and non-destructive bit-by-bit comparison arbitration rules,for industrial process control with high real-time and non-periodic message transmission,etc.,there are some limitations,such as long bus allocation time,high probability of using conflict,poor real-time processing ability and great complexity of application development.In order to improve the reliability of CAN bus network control for industrial process,CAN bus scheduling algorithm is always the focus of its application research.This paper is based on this background,based on markov chain dual trigger CAN bus scheduling algorithm(MDBSA)research.This paper summarizes the research status of CAN bus scheduling algorithm at home and abroad,as well as the structure model of CAN protocol,message frame format,medium allocation mechanism,and introduces TTCAN scheduling strategy,RM and DM static scheduling algorithm,EDF and LLF dynamic scheduling algorithm,and basic concepts and technical methods of markov chain.Based on the analysis of the construction conditions of double-trigger scheduling policy,TTCAN time scheduling table creation task and its parameter structure relation,the time characteristic markov prediction model of aperiodic message and the TTCAN time scheduling table creation parameter calculation method are established,A scheduling algorithm based on markov chain dual trigger CAN bus(MDBSA)is proposed and described in hierarchical and block ways.Simulink and Stateflow toolbox in MATLAB are used to design and implement the simulation experiment of CAN bus scheduling algorithm,Through the comparison and analysis of simulation and experimental results of RM scheduling algorithm,TTCAN scheduling algorithm and MDBSA scheduling algorithm,MDBSA algorithm can effectively reduce the conflict and contention of bus use allocation,reduce the delay time of message transmission,and improve the network utilization rate of the bus.