A Fault Tolerant Time Triggered Protocol for Drive-by-Wire Systems
Aakash Arora, Praveen R. Ramteke, Syed Masud Mahmud · 2004
Automakers are scrambling to implement advanced safety and engine management systems to make vehicles safer and more fuel-efficient, as well as meet growing consumer and government demands. Continuous demands for fuel efficiency mandate driveby-wire systems. The goal of drive-by-wire is to replace nearly every automotive hydraulic/mechanical system with electronics. Drive-by-wire and active collision avoidance systems need fault tolerant networks with time-triggered protocols to guarantee deterministic latencies. CAN is an event triggered protocol which has features like high bandwidth, error detection, fault confinement and collision avoidance based on message priority. However, CAN fails to ensure message latency which is critical for real-time applications. TTCAN (Time Triggered CAN) removes this fallacy of CAN by providing exclusive time windows for those messages that need deterministic latencies. An exclusive window is always reserved for a message that needs deterministic latency. In addition to the exclusive windows, there are arbitrary windows too, which make way for eventtriggered communications. In TTCAN, if an error occurs during the period of an exclusive window, retransmission of the message is not allowed. If this message is a safety critical message, the transmission error can endanger life. In this paper, we put forward a technique which helps solve this problem in a cost effective manner.