Platooning tested for first time on public roads

  • 22-Jun-2012 06:13 EDT
Volvo6-12Autonomous Platoon.jpg

Follow my lead: the first platooning test carried out on a public road involved three Volvos traveling autonomously, led by a truck.

“I honestly believe we will have autonomously controlled vehicles on the road within 10 years,” said Prof. Richard Parry-Jones, former global Chief Technical Officer for Ford and now a leading automotive consultant and U.K. government transport advisor. “Probably within 20 years, it will be the norm—not on every road but on major routes and motorways,” he told AEI in London.

Parry-Jones sees vehicles traveling in convoys at speeds up to 160 km/h (99 mph) with just 1 m (3.3 ft) separation between them and moving through bottlenecks with a very high degree of safety by obviating driver error, the greatest cause of death on the roads.

His prophecy coincided with the announcement that the European SARTRE (Safe Road Trains for the Environment) project had “for the first time ever” carried out a test of a road train comprising several vehicles automatically driving in convoy (platooning) behind a lead vehicle on a public motorway. The test, among other road users, was carried out near Barcelona, Spain, and described by SARTRE as having been highly successful.

Volvo is a joint member of the SARTRE project, which is part-funded by the European Commission under its Framework 7 program. “We covered 200 km in one day,” said Project Manager for the company, Linda Wahlström.

The project is led by Ricardo U.K., and other partners are Applus+Idiada, Tecnalia Research and Innovation, IKA (Aachen), SP Technical Research Institute, plus Volvo Technology and Volvo Car Corp.

The road train test comprised a truck with a professional driver as lead vehicle, followed by three cars: a Volvo XC60, V60, and S60 in a mixed-traffic environment. The cars were equipped with established driver/safety support systems including cruise control, emergency alert and reactive braking, linked to supporting cameras, radar, and laser sensors.

“By adding in wireless communication, the vehicles in the platoon mimic the lead vehicle using Ricardo autonomous control, accelerating, braking, and turning in exactly the same way as the leader,” explained Wahlström. “Driving among other road users was a great milestone.”

The platoon cruised at 85 km/h (53 mph) and the gap between each vehicle was 6 m (19.7 ft). This distance was selected following track development work during which gaps varying from 5 to 15 m (16.4 to 49.2 ft) were tried.

She added that the total test program to date has seen the vehicle fleet cover some 10,000 km (6200 mi). “From the purely conceptual viewpoint, autonomous driving works fine and road train will be around in one form or another in the future. We have focused hard on changing as little as possible in existing systems; everything should function without road infrastructure changes or expensive additional components in the cars.”

Their specially developed software plus the inter-communication between them are the only significant aspect to set the autonomous cars apart from regular showroom models.

Ricardo’s Tom Robinson, Project Director of SARTRE, explained that, although many challenges to full-scale implementation of the system remain, the test has demonstrated a practical approach to the implementation of safe road train technology, bringing improved road space utilization and reduced emissions—and that drivers become quickly acclimatized to the concept. Tests and analysis of results are now continuing, including fuel consumption measurements and a fuller understanding of the human factors involved, all of which will help toward platooning becoming operational on public highways.

Parry-Jones, who is Visiting Professor at Loughborough University in the U.K., said: “We are looking at more car-to-car communications; the big revolution is happening in the way that cars efficiently utilize the infrastructure that is provided for them. We cannot realistically match the demand from cars by building more and more roads, especially in critical bottleneck areas.”

In the past, he said, the automotive sectors had held back on congestion solving because it would have been heavily dependent on infrastructure, with the installation of such things as dedicated beacons. “But the way things are going, we are now of the view that cars will be able to do things themselves with very little help from infrastructure. There is now so much information intelligence and sensing on the car that most solutions can be worked out just by up-equipping vehicles.”

The use of smart phones to facilitate the convoy system would be probable, with drivers offered a choice of best routes. “These choices would be multimodal solutions—the best way to travel, which might be park-and-ride or to take a train.”

If a convoy needs to be joined, it would probably be a matter of driving to an entry ramp and the car polling vehicles on the motorway as it looks for a compatible convoy to mesh with for a required journey pattern/destination. It would then be a matter of driving up behind a line of moving cars, and the onboard sensors detecting the vehicle ahead. The autonomous system would then request the approaching driver to relinquish manual control.

“The car will autonomously close up to the rear of the convoy and later, as the required exit is approached, will instruct the driver to retake manual control, the convoy splitting as the exiting car leaves, any vehicles behind then closing up again.”

Although, like those involved in the SARTRE project, Parry-Jones does not see technology as the barrier, legal issues will need to be dealt with convincingly, and public acceptance may prove the biggest obstacle to such a radical solution. A program of persuasion and reassurance would be needed. “If customers will not voluntarily pay for higher fuel efficiency—and they don’t—then any company that decides to spend its engineering effort on something they do not want and will not buy is going to go bankrupt.”

Parry-Jones does not regard disparate types of cars with varying degrees of performance, braking, and general chassis competence as posing a problem. “Remember, all the cars are talking to each other.”

Although autonomously driven convoys may not completely avoid accidents, he believes that there will be far fewer and that any which might occur would be at lower speeds. He also sees what he regards as significant vehicle insurance cost savings because of the large reduction in accidents. And if a driver nods off to sleep in a convoy? “He or she will just miss their planned exit.”

Many other auto companies and specialist organizations are conducting R&D centered on autonomous vehicles as technology—notably sensors—now make the concept a potential reality.

The autonomous convoy theory is certainly not new and has seen research in Europe, the U.S., and Japan for many years.

In 1990, Prof. Dr.-Ing. Ulrich Seiffert, R&D boss of Volkswagen AG, and Prof. Dr-Ing Peter Walzer, a former Executive Director of Corporate Research at VW and then Vice President Technology with Seat in Spain, wrote a significant book, Automobile Technology of the Future, an SAE publication, which examined the potential of “convoy traffic” to overcome the delay in human reaction time to emerging or occurring emergencies on the road. Without this delay, a better utilization of the available capacity of the road network would be possible, with cars driving automatically, stated the authors.

Two decades ago, experimental work was carried out by VW in realistic conditions at its German proving ground as part of the pan-European Prometheus research program under the heading “Convoy Pilot.”

Seiffert and Walzer said presciently of the convoy concept that “this step forward seems possible with the help of electronic distance measurement devices, obstacle sensors, and the power of computers.” They also examined the possibility of autobahn lanes being modified to establish one specifically for autonomously guided vehicles.

More recently, VW was heavily involved in the DARPA (Defense Advanced Research Projects Agency) driverless vehicle challenge competitions (off-road and urban—the latter conducted on a disused airbase at Victorville, CA).

VW confirms, though, that to date it has not conducted a demonstration of autonomous driving on a road used by the public and that it has “no plans” for such a demonstration in the near future.

But a VW executive did point out that arguably the concept of the autonomous vehicle, with no manual input to accelerator, steering, or brakes, could be said to have begun centuries ago, when a very relaxed driver left an inn and returned to his horse and wagon to be taken home without any input from voice, whip, or reins.

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