Data Logging for Controller Area Network of Autonomous Vehicles : An Investigation of a CAN-Ethernet Gateway

Abstract: With the development of autonomous vehicles, more and more technology is introduced into the automotive industry. Ethernet has found its way into the vehicle network, and it is forced to coexist with the well-established CAN bus. In terms of data acquisition, the presence of a mixed network brings challenges with significant changes in network architecture. This thesis explores CAN-Ethernet gateways as a replacement for the PCIe bus CAN transceivers utilized in today's logging systems, with the purpose to improve the adaptability of the autonomous logging system. A CAN-Ethernet gateway was implemented using Kvaser's DIN Rail SE400S-X10in an experimental comparison against the PCIe logging solution, including both classical CAN and CAN FD communication. In addition, a case study on the benefits and drawbacks with implementing an Ethernet architecture was performed, utilizing semi-structured interviews. It was concluded that a CAN-Ethernet gateway provides a robust solution in relation to data loss. Throughout the tests, the message loss rate was 0% for both logging solutions. However, CAN-Ethernetlogging introduced additional delay into the system. For the tests on a truck simulation rig the mean additional delay from a CAN-Ethernet gateway, compared to the existing PCIe-CAN logging, was 2 ms. Moreover, some spikes occurred and in a number of cases it could be up to 6 ms in additional delay compared to the existing PCIe logging. It was also proven difficult to time synchronize the gateway with the autonomous logging system, and unknown delays had an impact. Relevant metrics were obtained from relative measurements of side-by-side logging between the PCIe and CAN-Ethernet communication. The standard deviation and fluctuation of the delay were relevant metrics, since smaller fluctuations made the delay more predictable and real-time compatible. A CAN-Ethernet deployment may create a more complex architecture in general, and as of now has limitations for real-time systems. On the other hand, it may offer significant possibilities in future development of a more adaptable and scalable logging system.