Under the skin: How the new automated lane system will work

Plans to introduce to Britain the Automated Lane Keeping System (ALKS), which is described as a “traffic jam chauffeur technology”, is likely to accelerate the need for more robust autonomous technology than exists on our roads today.

The Department for Transport, which has launched a consultation on its possible use, says ALKS will allow vehicles to stay in lane on motorways without the driver having to do anything but be prepared to take back control when prompted. One of the questions the consultation document poses is “should the UK permit the use of ALKS up to 70mph?”, but the ALKS regulation approved in June 2020 by the United Nations Economic Commission is for a system (in its current form) capable of operating at up to only 37mph.

ALKS is effectively a beefed-up blend of two existing technologies: lane-keeping assistance (LKA) and adaptive cruise control (ACC). These already work at motorway speeds, although some LKA systems take greater control than others. Today’s LKA systems use a stereo camera behind the windscreen to keep an eye on road markings. Its image is run through image-processing software and interpreted, easing the car back into lane if necessary, either via an electric power steering system or by gentle application of individual brakes.

ACC came along in the early 2000s, using radar sensors to maintain a safe distance behind the vehicle in front. Since then, it has evolved a lot. Whereas it could only work down to a certain speed before handing control back to the driver, the latest stop-and-go versions work down to a standstill and do what their name suggests in queues.

More recently, multipurpose cameras have been added to achieve greater accuracy. Bosch ACC systems read the road ahead with a stand-alone radar sensor plus a combined radar sensor and multipurpose camera. Automatic emergency braking adds corner radar sensors to the forward-facing radar and multipurpose camera.

The combined camera and radar is an example of sensor fusion, where the strengths of each are combined to make a sort of super-sensor. The radio frequency-based radar is best for measuring longitudinal distance and speeds (hence the acronym radar, which stands for radio detection and ranging) in any weather, day or night. The camera adds definition and precise measurement of lateral movements.

Hardware is combined with artificial intelligence software to interpret boundaries and give reliable lane detection. Data fusion also allows static or moving objects to be acquired, identified and tracked to build up an accurate, high-definition picture of what lies ahead. The hardware creates a ‘road signature’ good enough for a car driving autonomously to work out its precise position relative to its surroundings, which in autonomous vehicle speak is known as localisation. It’s this kind of advanced sensing and artificial intelligence that’s likely to form the basis of the higher-speed ALKS being investigated for the UK.