Evolution of automotive EMC testing(2)

The demand for connected and autonomous cars is also causing changes in the electromagnetic environment in which vehicle control systems must operate with the inclusion of high-frequency vehicle integrated technologies, such as 5 GHz WiFi and the 6 GHz ITS. This is driving changes to both the susceptibility test frequencies and emissions bands included in International and OEM EMC standards, for both component and vehicle requirements. This has the knock-on effect of increasing the bandwidth and upper frequency of the EMC test antennas we utilise, the measurement requirements of our test receivers and the capabilities of our power amplifiers.

Meeting vehicle styling constraints whilst ensuring the robustness of wireless systems is another challenge EMC engineers face. Manufacturers are keen to maintain the aesthetics of the cars they're selling and don't want them to be laden with antennas. The trend is for antennas to be concealed in structural elements which degrade their performance. To ensure that antennas transmit and receive signals at levels that meet functional requirements, they need to be performance tested.

Testing of next generation vehicles will require a different approach in comparison to current vehicles. The same simulated test targets used to verify the operation of forward facing RADAR and other single sensor systems will still be used to test the multiple sensor systems that will be fitted to autonomous vehicles including 360° peripheral camera systems and LiDARs; however there will need to be a greater level of diagnostic information available to understand which systems are in error if RF related events are uncovered. The reliance of automated systems on a combination of signals from all available sensors and inputs, and the increase in safety requirements means that understanding the source of malfunctions will require a significant increase in effort during the EMC engineering process. As more wireless and high technology features continue to be added to vehicles, the need for diagnostic information will only grow along with the need to ensure that these systems are safe, robust and reliable in their intended electromagnetic environment.

In order to adequately assess the driverless cars of the future, the next generation of sophisticated test facilities are required. One such facility is the 'Antenna Arch' facility, a chamber with an arch reaching over a turntable on which the test vehicle is placed and turned. The arch transmits and receives signals to and from the car's communication systems. This allows engineers to determine the hemispherical characteristics of the vehicle antennas which creates a 3D picture of how well the antennas are performing.

Another facility designed for EMC testing in a driverless world is a programmable test track, such as HORIBA MIRA's 'City Circuit'. This test track can be programmed by engineers on site using a laptop to simulate different signal environments that are likely to be encountered on real roads. Specific issues including signal obstruction, urban canyons, tunnels and multipath propagation can be simulated. This provides test engineers and evaluators with the ability to make subjective assessments of the performance and robustness of on-board systems, a capability which is particularly useful for the development of infrastructure communications for ITS.

Looking ahead
Engineers, OEMs and the wider motor industry can do a number of things to ensure vehicle systems remain robust. The motor industry is unforgiving in its attitude to supplier conformance, and companies wanting to compete in this market will have to meet stringent OEM specifications that are tighter than the demands imposed by legislation. Training and awareness in the latest standards are key, as is access to the right facilities through working with EMC test consultancies at the forefront of their field. As the race for superior connectivity and services between vehicle manufacturers continues to forge ahead, there will be a continued need to address EMC test and development issues facing vehicle manufacturers. Working together with EMC test engineers, vehicle manufacturers will be able to develop robust systems for their increasingly complex and autonomous vehicles.

About the author
Anthony Martin is EMC Chief Engineer at HORIBA MIRA.