EMC testing for the car of the future

| Transport | Environmental Testing

Mercedes-Benz Future Truck 2025

Progress in driverless and connected cars is driving technology innovation in EMC test facilities to cope with their increasing complexity by Jonathan Newell.

They may have been a mere fantasy or a curious vision of the distant future in episodes of “Tomorrow’s World” until they entered general conversation recently, but driverless cars are now much closer to reality than many think, with some predicting that they may even become mainstream before the end of the next decade.

To operate with other vehicles and infrastructure around them, enormous amounts of work need to be done in vehicle design, infrastructure development and the internal connectivity of vehicle systems. The Information and Communications Technology (ICT) content of vehicles alone is going to rise at a phenomenal rate. As a result, the motor industry can expect major changes in directives, standards and regulations to accommodate all these additional electronics, causing conformance headaches for vehicle and sub-system manufacturers.

Autonomous vehicles already here

Work on bringing driverless vehicles to the market has already begun. Daimler-Benz is one manufacturer at the forefront of autonomous vehicle development. The company has already scored two firsts: “The Future Truck 2025” was launched with partial autonomy and full fanfare at the 2014 Commercial Vehicle Show in Hanover and the first 100km fully autonomous drive took place on mixed public roads between Mannheim and Pforzheim, which used an experimental Mercedes S-500.

Not wanting to miss out on the opportunities for local industries, Britain is catching up and has formed the “UK Autodrive Consortium”, consisting of major vehicle manufacturers, city councils, software suppliers and MIRA, the UK vehicle engineering, test and certification body.

The inclusion of MIRA within the consortium is of significance, not only because of its considerable experience in advanced vehicle technology, but also due to its homologation and certification abilities. As an EMC test and engineering centre, MIRA will play a significant role in ensuring that commercial autonomous vehicles will meet the current and future versions of the EU directive on automotive EMC.

EMC compliance

Much of the progress towards driverless cars is geared towards the gradual integration of existing Advanced Driver Assist Systems (ADAS). Existing ADAS technology includes autonomous emergency braking (AEB), adaptive cruise control, lane departure warning systems, infra-red sensors for detecting pedestrians and animals at night and much more.

As each of these innovations makes its way onto the market, MIRA adapts its testing process and facilities to accommodate them. According to the organisation’s Chief EMC Engineer, Anthony Martin, a constant process of upgrading test equipment is necessary to ensure that the new functions are able to be tested under Radio Frequency duress.

Since many of these functions involve the replacement of human senses, reactions and vehicle control, there are significant safety implications and so more rigorous testing is required. This is one of the challenges that future vehicle autonomy is posing for MIRA.

Autonomy and connectivity

One of the advantages of autonomous vehicles is the freedom they give to the driver, who will be free to enjoy more entertainment, connect to the internet, read e-mails and communicate with the outside world. The apparent paradox is that the sensitive sensors and vehicle control systems become more vulnerable to interference from the escalating number of infotainment systems.

Airline passengers are always told to switch off mobile phones as they may interfere with aircraft systems – so will the same be true for the driverless car? Anthony Martin believes that this is unlikely and MIRA has a specific test routine which involves using multiple telephone signal transmitters of different powers used simultaneously to stress the robustness of vehicle systems against interference from mobile devices.

He explained that having robust control systems that resist interference is essential in an increasingly connected world where car occupants aren’t going to switch off their mobile phones and Wi-Fi enabled computers just because of the threat to vehicle control systems.

Wireless technology and ITS

MIRA test car and stop signPerhaps the biggest change to the EMC environment in driverless cars is the significant shift from wired devices towards the use of wireless technology as part of the emerging Intelligent Transport System (ITS) environment. Apart from vehicle control systems, which are usually wired, autonomy also relies heavily on external communications between the vehicle and other vehicles on the road and between the vehicle and the infrastructure. These so-called V2x communications are at the foundation of ITS and their reach and reliability depend on the quality and RF protection of the antenna, of which there are many on the vehicle.

Manufacturers are keen to maintain the aesthetics of the cars they’re selling and don’t want them to be bristling with aerials so the trend is for antennas to be concealed in structural elements which degrades the performance.

To ensure that signals are transmitted from the antennas and received by them at levels that meet functional requirements, they need to be performance tested.

Test facilities of the future

Microwave Vision Antenna Arch
SG 3000F antenna arch from Microwave Vision

Antenna testing at this level requires the next generation of sophisticated test facilities that haven’t yet been commissioned at MIRA but which will soon be installed. The “Antenna Arch” test facility is a three-metre 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 and perform Over The Air (OTA) wireless connectivity assessments.

This represents the direction in which testing technology is heading in order to adequately assess the driverless cars of the future.

Other innovations include the MIRA “city circuit”, a test track that can be programmed by engineers on site using a laptop to simulate different signal environments that are likely to be encountered on real roads. 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.

The supplier challenge

The future of connected and driverless cars is presenting new opportunities for Tier-1 and aftermarket equipment suppliers to the motor industry. These opportunities are already creating a highly competitive environment in which the winners will get high quality and innovative products to market quickly and at the right price.

The motor industry is unforgiving in its attitude to supplier conformance and companies wanting to compete in this market will have to meet stringent specifications which are much higher than the standards demand, including EMC standards.

For example, component emission levels are considerably lower than vehicle requirements so that cumulative effects are avoided when pulling them together into a higher assembly.

With safety-critical autonomous features being set to become the norm, these requirements from vehicle manufacturers are likely to become even tighter. However, meeting specifications and complying with regulations is being made easier with the increasing availability of the latest test chambers and engineering services that can be used throughout new product development phases to avoid the shock of failure and the potential for going through expensive redesigns at a time when the product should be starting deliveries to the customer.

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