2_1 / texts_exercises / Now who's in the driver'seat

Now who's in the driver's seat? Computers and cars already have one thing in common: they crash. But put them together and the performance improvements are impossible for the car industry to ignore.

Duncan Graham-Rowe. 

New Scientist 180.2420. (2267 words) 

IT IS one of those coincidences of history that Henry Ford established the Ford Motor Company in the same year that the Wright brothers made their first flight. And now, 100 years later, these two technologies are becoming more closely intertwined than ever.

In the next few years we will start to see cars adopting one of the key elements of aircraft design. They won't fly, but they will take the radical step of severing all mechanical connections between the driver and the car. No longer will drivers have their hands and feet on the car's real controls. Instead, any movement of the steering wheel or pressure on the pedals will be fed to a computer, which will be entrusted with the tasks of controlling the steering, acceleration and braking.

Taking control away from the driver might seem unnecessary, even reckless. But it is old hat in the aviation industry, where "fly-by-wire" technology has been used successfully for 30 years. The automotive equivalent, drive-by-wire, is not quite ready for market, but all the major car makers are developing it and the first cars using elements of the technology are already on the road.

According to the manufacturers, drive-by-wire will make cars easier to handle, more fuel efficient and, above all, safer. They point out that fly-by-wire has transformed aircraft performance, and say that it is time to do the same for cars. But to some computing experts, the parallels with aviation are worrying. Fly-by-wire might be foolproof now, they argue, but it was not always so. While no air crash has ever been officially blamed on a fly-by-wire system going wrong, it still took years of tweaking before aircraft designers got it absolutely right. Who's to say the car industry won't suffer teething troubles too, and with serious consequences?

The idea of handing control of your car over to a computer is nothing new. Computerised cruise control has been around for years, and today there are cars that automatically correct your steering when you stray out of your lane, or sense when you are about to crash and apply the brakes. Soon, some cars will even try to protect passengers if the car turns over, closing the windows and sunroof, and tightening the seat belts automatically.

But drive-by-wire goes much further. Rather than adding non-essential functions, drive-by-wire places the car's critical control systems--the brakes and steering- directly under the computer's command. The motivation for doing so lies in the competitive nature of the motor industry, where companies will go to extraordinary lengths to gain even a small advantage over their rivals. Until now they have been able to use traditional design techniques to eke out better performance. But this progress is reaching a plateau, so car makers are turning to computer control to squeeze the most out of their designs.

By making the brakes, suspension and steering work together, for example, a computer can optimise them to ensure the car grips the road better on bends. Improved handling increases fuel efficiency and makes the car more enjoyable to drive, says Nick Zielinski, director of vehicle and technology integration for General Motors in Michigan.

From a driver's point of view, however, very little will change. While companies such as DaimlerChrysler are showing off futuristic prototype cars controlled by joysticks, the reality is that most drive-by-wire cars will look and feel like a conventional car. You'll press the same pedals and turn the same steering wheel. But behind the scenes the car will make subtle modifications to your driving, improving the way you take corners, smoothing acceleration and making sure you don't throw the car into a skid when you hit the brakes. The result will be a car that handles better and uses less fuel.

As well as improving performance, drive-by-wire can lead to new capabilities, Zielinski says. "Active steering", for example, can amplify the driver's turning of the steering wheel, making it possible to pull the front wheels all the way to their "lock" with the minimum of movement--a big help when parking in a tight space. Similarly when the vehicle hits ice or a tyre blows, the computer can react faster, and probably in a more appropriate way, than any driver could to ensure the car does not skid out of control.

So when is this going to happen? At the moment the only place you will see full-on drive-by-wire is in concept cars built by car manufacturers to show off their latest gizmos. That is unlikely to change for at least five years. But drive-by-wire technology is creeping into the showrooms. It already controls the throttle in some cars equipped with cruise control. And in 2001, GM launched a range of four-wheel-steering vehicles in which the front and back wheels can be turned simultaneously to manoeuvre into a tight parking space. This is not the first time four-wheel steering has been seen, but GM's rear-wheel electronic steering is the first use of drive-by-wire steering on a production car.

As far as the industry is concerned, it is only a matter of time before drive-by-wire becomes standard. But some safety experts are questioning the wisdom of this radical change. They point out that fly-by-wire has a bumpy track record. Will the car industry learn from these mistakes, they ask, or make them all over again?

The first fly-by-wire planes were developed by the military in the early 1970s. Aeronautical engineers seeking to make jets more manoeuvrable discovered that there was a trade-off: the more agile they made the jets, the more unstable they became. This instability could be compensated for using the ailerons, rudder and other control surfaces, but the reaction times required were far faster than a human pilot could manage. So the engineers decided to dispense with traditional controls and hand them over to computers. Where previously the pilot controlled the ailerons and rudder directly, using a joystick and pedals, now a computer-based flight control system intervened to manage the lot.

Today, many commercial aircraft use fly-by-wire, most notably the Airbus A320, which went into service in 1988 and has since become a workhorse of the industry. Pilots still operate cockpit controls similar to the old stick and rudder, but their commands are fed through 150 onboard computers before being translated into action. "It's a computer network with a plane wrapped around it," says Peter Mellor, an expert in software reliability at City University in London.

Safe and sound

While drive-by-wire systems will not need quite this level of complexity, they will use similar safeguards to ensure that everything runs smoothly. Think of the word "computer" and the word "crash" surely follows--not a happy notion when attached to planes or cars. So allowances have to be made for when things go wrong.

All software designers strive for reliability, but for safety-critical systems such as electronic brakes the mantra is more demanding--"reliability and availability". What this means is that the system must keep working even if the software starts playing up.

One technique for providing reliability and availability in aviation is to have four completely different computers looking after each critical system. "They use different programs, written by different programmers in different languages," says Tom Anderson from the Centre for Software Reliability at the University of Newcastle upon Tyne in Britain. Before any action is carried out the computers vote on how to proceed. This provides two layers of redundancy so that even if one computer fails altogether and another starts acting up, there will still be two in control.

Drive-by-wire will use the same approach, says David Ward of the Motor Industry Software Reliability Association, a British consortium set up by the motor industry to develop standards for drive-by-wire technology. But this imperative is creating an unexpected problem: it is proving difficult to cram all the computing power into a car without eating into its performance.

The reason, Ward says, is that to be truly fault-tolerant you need more than multiple computer control systems; you need multiple sensors and actuators too, and these all add to the weight of the vehicle. And while there are weight savings to be had from removing mechanical systems such as the steering column, Zielinski says the first drive-by-wire cars will probably have to keep the mechanical systems as back-up.

Even with the safeguards in place, things can still go wrong. In 1988, an Airbus A320 crashed at an air show at Mulhouse-Habsheim airport in France. It was the first time a fly-by-wire passenger plane had crashed and the circumstances still generate controversy.

The official investigation blamed the pilot, but the pilot claimed that the fly-by-wire system was at fault. He said that during a low fly-over of the airfield, he attempted to increase the thrust from the plane's engines but there was an unexpectedly long delay before he got it. He was unable to pull the plane up in time to clear the trees ahead and it crashed, killing three passengers.

According to the accident report the software worked correctly and a delay was only to be expected when thrust was switched from an automatic setting to manual. A delay was built into the system to protect the engine from sudden, large changes in power. The pilot failed to take this into account and so was culpable, according to the report. Investigations into other crashes involving fly-by-wire planes have come to similar conclusions, says Mellor.

But according to Mellor, this illustrates a potential problem with drive-by-wire technology. Even if the software is working perfectly, its specifications may not be quite right. Indeed, most experts agree that the greatest challenge for drive-by-wire lies not in developing the software but in anticipating how people will use it. "There is an element of human-computer interaction," Mellor says. "You have to look at the system as a whole."

And this is where the greatest challenge lies. Designing safety-critical software is difficult enough without having to predict how people are going to use it, says Nancy Leveson, an aeronautical software expert at the Massachusetts Institute of Technology. "You have got to anticipate every possible situation," she says, which is impossible.

The designers of drive-by-wire systems may fail to anticipate all the actions that could be taken by drivers in response to the car's behaviour, leaving loopholes in the system that could lead to an accident. What, for example, would happen if a driver tried to avoid an obstacle just after a tyre burst? Would the steering allow for this or would it try to keep the car straight? This scenario would be easy to test, but there are thousands more like it. According to Leveson, it will be impossible to anticipate every one, let alone test them.

One thing's for sure, she says: anticipating human-computer interaction is going to be even more difficult for cars than it has been for planes. This is because cars operate in a much less constrained and regulated environment. Pilots are highly trained, have co-pilots as backup and air traffic controllers watching over them. With cars it is a different story. "You don't even have to be sane to drive a car," Leveson says. And while Ward says the problem could be tackled using well-established techniques for assessing human-computer interaction, he too recognises that it will not be possible to predict every scenario. It might be sensible to start thinking about giving additional training to the drivers of drive-by-wire cars, he says.

The intimate meshing of driver and software raises another question: who can be said to have ultimate control over a drive-by-wire vehicle? If the software fails to prevent a crash, who is responsible for the consequences? Given the "at fault" nature of car insurance, this is more than a hypothetical question.

Again, an episode from the fly-by-wire experience is instructive. In its first year of operation, an Air France A320 was briefly taken out of operation when a warning light came on indicating the landing gear was not fully engaged, even though it was. When engineers failed to find anything wrong, the plane was allowed to fly again. Eventually, after 12 months and following a similar incident, a faulty piece of computer hardware was identified and replaced.

Part of the reason such problems prove so hard to pin down is that with complex systems, it can be difficult to reproduce the precise conditions that caused the fault. If something similar happened in a car and caused a crash, the driver could end up out of pocket even though it was the car itself that was at fault.

Already the issues raised by drive-by-wire are being tested in court. In the US, Ford has been sued by a number of customers who claim their drive-by-wire cruise controls caused sudden surges of acceleration with no prompting from the drivers. Some experts are pointing the finger at inadequate shielding of electronic components governing the cruise control, making them vulnerable to electromagnetic interference from elsewhere in the vehicle. Ford denies that its cruise control is at fault in these cases. It claims that its engineers cannot repeat the supposed fault and denies that interference is a problem.

Whatever teething troubles drive-by-wire suffers, the motor industry will probably overcome them, just as fly-by-wire innovators did in aviation. And no doubt people will accept the technology. After all, millions of people now regularly travel on fly-by-wire planes. But in the meantime, the marketing people have a job on their hands. How are they going to persuade us to hand control of our cars to a technology that is synonymous with the word "crash"?

Duncan Graham-Rowe is a freelance journalist based in Brighton