Blog: What is a true AV Level 4 autonomous vehicle?

For many years people have been waiting with bated breath for the promise of completely autonomous vehicles (known in the industry as AV Level 5) and, in truth, they’ll have to wait a little longer whilst technology, legislation and infrastructure mature. True Level AV level 4 vehicles are here now! The technology and legislation for them to operate on our UK road systems is in place and ready to be demonstrated.

In simple terms AV Level 5 is a fully autonomous vehicle with no driver controls whatsoever, it can take you anywhere you might drive a regular manually driven vehicle. AV Level 4 vehicles operate in more limited areas known as the “operational design domain (ODD)” – meaning it does not cover every driving scenario an AV Level 5 vehicle will need to be capable of negotiating safely.

You have to walk before you can run and developing AV technology safely is no different. In order to achieve a safe AV Level 4 vehicle Fusion Processing have taken the decision to build redundancy into every safety critical system of the full-sized autonomous buses we are developing for the world’s largest and most complex public trial, CAVForth. This means there are two mechanisms for the onboard computers to control the steering, brakes and throttle. The vehicles also retain the regular driver controls so they can be operated in both manual or autonomous modes. The full sized 43-seater buses we are developing with our partners Stagecoach, Alexander Dennis Ltd, Napier University, Transport Scotland and the Bristol Robotics Lab for the CAVForth project will have two independent steering mechanisms and two separate braking systems. This ensures that if in the highly unlikely event there is an issue with one system, the other automatically kicks in and the vehicle can complete the journey without the safety driver needing to intervene.

Hang on, I’ve seen autonomous vehicles on the road for years?
AV Level 2 and 3 autonomous vehicles have been taking part in trials and indeed, are available to buy with ‘Autopilot’ systems. These have been fantastic development milestones, but the human driver has effectively been the back-up redundancy to the computer systems where they have to take over control of the vehicle. With the best will in the world, it is unreasonable to expect a driver in an AV Level 2 or 3 vehicle to remain 100% alert and ready to take over from the computer at any moment, for hours upon end. We, Fusion Processing, believe AV Level 4 and 5 has to be the ultimate target and full redundancy in the critical systems is the best way of achieving it safely. We’re delighted to say the technology is ready to hit the UK roads and begin testing in earnest.

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Who set the levels of driving automation?
The internationally acknowledged six levels of autonomous vehicles were set by SAE International, a global association of more than 128,000 engineers and related technical experts in the aerospace, automotive and commercial-vehicle industries. Their core competencies are life-long learning and voluntary consensus standards development.

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