F2008-05-066
A Method for Improving Reliability of Gateway by Using OSEK/VDX and Duplication Scheme
The gateway system for automotive system has become an essential component for network-to-network communication using different protocols inside a distributed system. Since reliability is an important aspect in an automotive system, we propose a method for improving the reliability of the gateway system by using OSEK/VDX(Open systems and the corresponding interfaces for automotive electronics/vehicle Distributed eXecutive) and duplication scheme. We consider five factors for improving the reliability of the gateway. Firstly, a high priority messages must be processed first by using OSEK Operating System(OS). We use direct forwarding mechanism for critical messages and routing table mechanism for non-critical messages. The direct forwarding mechanism uses dedicated task to process received messages therefore it is faster than routing table mechanism but it uses more resources. The routing table mechanism uses routing table for searching destination node which requires additional time to find destination node in routing table. However, it only requires one common task for processing received message therefore less resources are used. Secondly, the gateway should check the deadline of each messages by using OSEK Communication(COM). We implement OSEK COM and use deadline monitoring mechanism supported by OSEK COM for checking the deadline. Thirdly, the gateway should not transmit messages to erroneous nodes which cannot receive messages. We implement OSEK direct NM and indirect NM mechanism to check the status of destination node. When destination node is not accessible, the gateway tries to search alternative path and send messages to alternative path. If there are no alternative paths, the gateway suspends transmission of messages until the destination node can operate normally. Fourthly, duplication gateway should be used alternately with the main gateway when the main gateway cannot operate correctly. We use only two duplication gateway system: one is main gateway and the other is sub-gateway. Fifthly, the gateway should store log data to nonvolatile memory for diagnostic when it cannot process normally. In this paper, we develop a LIN, CAN, and FlexRay gateway embedded system and estimates the reliability of gateway by applying our method. We show difference of reliability between gateway with and without using our method in stable, normal, and unstable environment respectively. We use 32-bit embedded system to implement gateway embedded system and use Freescales´ OSEKturbo which is one of the commercial version of OSEK OS.
Poster presentation: Electronics