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Development of strategies for reducing the worst-case message response times on the Controller Area Network

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2012
Çelik, Vakkas
The controller area network (CAN) is the de-facto standard for in-vehicle communication. The growth of time-critical applications in modern cars leads to a considerable increase in the message tra c on CAN. Hence, it is essential to determine e cient message schedules on CAN that guarantee that all communicated messages meet their timing constraints. The aim of this thesis is to develop o set scheduling strategies that find feasible schedules for higher bus load levels compared to conventional CAN scheduling approaches. We formulate the o set scheduling as a constraint optimization problem that maximizes the sum of message slacks where slack is defined as the di erence between the deadline and the worst-case response time (WCRT) of a message. The constraint to ensure the feasibility of the schedules is keeping all slacks positive. In this respect we propose two heuristic o set scheduling algorithms which integrate an existing method for the WCRT analysis in the schedule computation. We apply our algorithms to various examples and compare the results with a well-known o set scheduling algorithm. The results show that our algorithms can generate feasible schedules at significantly high loads with run times shorter than 5 minutes.