Development and testing of a race car data network

Abstract

The University of Malta Racing Association build and race their own racing car in an international competition called Formula SAE. Lately the complex analogue network linking the several sensors to the engine control unit where it would be converted into a digital signal and logged was identified as a major area that needed sorted out. Converting the analogue network to digital was on top of the agenda. Research was conducted in order to analyse the different automotive networks present and identify the network that worked best for the requirements set for the race car. The Controller Area Network (CAN) was thus chosen. In order to implement CAN it was decided to design and construct the basic nodes instead of using development boards. When designing the PCB, a number of different terminations were added apart from the basic 120 ohm resistor in order to mitigate the network susceptibility to noise. Another integral component of any network is the physical medium upon which data is transmitted. In this case two media were used one was a 120 ohm characteristic impedance twisted pair and shielded cable whilst the other was a CAT5e Ethernet cable that was commonly available. After the construction of the different nodes, the nodes were tested for their compliancy with the ISO 11898:2 (High-Speed CAN Protocol) using a CAN Bus Analyser. A network of a few interconnected nodes was built when to check that the network worked according to specification. The next step was to test the network’s susceptibility to noise. This was tested by injecting a continuous wave (CW) sine wave signal onto the bus and an analysis of the performance was recorded and discussed for several terminations and the cables mentioned earlier. The tests were repeated using an amplitude modulated signal. The dissertation concludes with recommendations on terminations to be used in relation to the environment of the network and suggested scope for further work.