Issues Related to the Design of a Time Triggered CAN System for Future Intelligent Vehicles
Syed Masud Mahmud · 2005
The demand for drive-by-wire, telematics, entertainment, multimedia, pre-crash warning, hit avoidance, remote diagnostic, software update, etc. will significantly increase the complexity of the future commercial and military in-vehicle communication networks. New types of communication networks will also be necessary to satisfy the requirements of safety and fuel efficiency, and meet the demand for new features. Different sets of vehicle electronic modules will require different types of networks. For example, drive-by-wire and active collision avoidance systems need fault tolerant networks with time-triggered protocols, to guarantee deterministic latencies; multimedia systems need networks with high bandwidth to transfer video files; and body control electronics need low-bandwidth networks to keep the cost down. Recently, CAN protocol gained wide acceptance among the automotive industry due to its superior performance over other protocols. A Time Triggered CAN (TTCAN) system can be implemented on the top of the existing CAN system for drive-by-wire and safety critical applications. However, there are a number of issues related to the design of a TTCAN system. Some of these issues include the design of master and potential master nodes, synchronization of the master node with other nodes, take over of the system by a potential master node when the master dies, selection of a common Network Time Unit for the system, etc. Each one of these issues must be properly resolved before an acceptable TTCAN system can be designed. This paper presents a detailed description of these issues and then explains how these issues can be resolved under various types of system environments.