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Driverless cars just around corner | Lexus

Everyone has heard the story about the tourist whose motorhome crashed after he set the cruise control and then strolled into the back to make a cuppa. It may be an urban myth, but technology marches on and you get the feeling the driverless car may be just around the corner, or certainly a lot closer than anyone thinks.

This week Lexus demonstrated a further development of the active cruise control system fitted to its cars that steers and brakes the car without any need for intervention from the driver. It is still under development but Lexus hopes to bring the system to market within two years.


Described as the next-generation advanced driving support system, Automated Highway Driving Assist (AHDA) links two automated driving technologies. At this stage its use is confined purely to the open road because city streets present too many variables such as pedestrians, motorcycles and in some cases an absence of line markings.


We received a first-hand demonstration of the system in Tokyo. Although we were not permitted to actually drive the Lexus GS fitted with the technology, neither in effect was the driver whose hands remained off the steering wheel, although they hovered close by.

It works, and Lexus has data to show it does a better job of keeping the car on a straight course than your average driver. Spin-off effects include a reduction in traffic congestion as well as lower fuel bills.

Curiously, the further back you are in a line of cars using the system, the greater the reduction in fuel consumption because of the 'drafting' effect (the reason cyclists ride in a peloton).

In a column of four vehicles, consumption was down 5.3 per cent in the first vehicle, 17.7 per cent in the second and 26.8 per cent in the third - with an overall reduction of 11.1 per cent.

Mind you the figures were derived over a period of four minutes and a distance of just a couple of kilometres.


The system brings together Cooperative-adaptive Cruise Control, which wirelessly communicates with the vehicles in front to maintain a safe distance plus Lane Trace Control, which aids steering to keep the vehicle on course within the lane.

Key to its success are a camera which monitors lane markings, together with GPS mapping of the route ahead and sensors in participating cars that enable them to talk to each other.

In contrast to standard radar, Cooperative-adaptive Cruise Control uses 700-MHz band vehicle-to-vehicle ITS communications to transmit acceleration and deceleration data which allows vehicles following behind to adjust their speeds accordingly to better maintain their distance. 

Lane Trace Control draws on high-performance cameras, millimetre-wave radar and control software to enable an optimal and smooth driving line at all speeds. 

The system adjusts the vehicle’s steering angle, driving torque and braking force where necessary to maintain the optimal line within the lane. By reducing unnecessary acceleration and deceleration, the advanced driving system improves fuel efficiency and helps reduce traffic congestion.

It's only a hop, skip and a jump from here to driverless cars, but the engineer who demonstrated the system to us said Lexus has no plans to introduce full automation.

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