Feature: Control freaks.

Jenson Button stamps on the throttle of his Lucky Strike BAR Honda: the car lurches forward. Easy. How to drive, lesson one. Right foot, plus throttle, equals acceleration. Simple, right? Well no, actually. This is Formula 1. Nothing is ever that simple...

The man-machine interface:

In most sports, it is the performance of the athlete alone that must be optimised to be competitive. If a footballer plays better or a triple-jumper triple-jumps further, it is all down to them. In Formula 1, it's a little different. Of course, a driver always strives to drive better and, as Jenson will tell you, an F1 driver needs to train as hard as any other world class athlete. Driving a grand prix car is an incredibly demanding experience and drivers need to be super-fit to cope with the extreme braking and g-forces. But the driver, however fit and however skilled, is always limited by his car.

It's a no-brainer that the car should be as quick as possible. Less obvious is the need to engineer the relationship between the driver and the car. In F1 speak, the man-machine interface needs to be optimised just as much as man and machine individually.

It is the job of Gianni Sala - chief control systems engineer - to do this at BAR.

"I try to make the driver's life in the car as easy as possible," he explains.

On one level, Gianni's job is the most pragmatic of automotive engineering tasks: designing control systems that make the car go, stop and turn at the driver's request. But on another level his job is deeply significant, almost metaphysical in its implication. For it is Gianni's job to make man and machine, as far as possible, become one.

The man-machine interface is one of the most important and complicated aspects of a Formula 1 car. As much as possible the car must be an extension of the driver. Whether it be throttle, steering, gear selection, or changing a setting on the traction control, every control input a driver makes must be realised mechanically as quickly and precisely as possible.

Electro-hydraulic control:

Making an F1 car do what the driver asks is a lot more complicated than it sounds. Control is all about information transfer. Just as the muscular movement of the driver is caused by a chain reaction of messages in his brain and nervous system, so mechanical movement of the car is caused by a chain reaction of messages through the car's brain and nervous system.

The car's brain is its ECU (electronic control unit). This is where most control information is inputted and processed. The nervous system is its network of wires and hydraulics. The wires are like sensory neurones, carrying messages from driver input to the ECU. The hydraulic lines are like motor neurones, carrying messages from the ECU to the car's mechanical control components.

Most control systems on the car are a combination of electronics and hydraulics. This is the case for the throttle, transmission, traction control, differential and many others. The basic sequence of information transfer is as follows:

Driver input - electronic signal - ECU (signal processed) - electronic output signal - hydraulics system - mechanical movement of component

In the case of power assisted steering and brakes, the rules forbid the use of any electronic control. In these cases the control system is still hydraulic but mechanically operated:

Driver input - hydraulics system - mechanical movement of component

The Brain: ECU:

The ever-increasing role of electronic control has been one of the most contentious issues in Formula 1 in recent years. The purists feel that electronics have taken away far too much from the skill of driving the car, particularly in the area of traction control. Others feel that advanced electronics are essential if F1 is to remain the pinnacle of motorsport.

Whatever your take on the whole debate, there is no denying the impact electronics have made in F1 over the past ten years. A modern F1 car is now so heavily dependent on its ECU to carry out thousands of functions every second (functions that no driver would ever be able to perform unaided) that the car would be pretty much undriveable without some form of electronic control.

This is not to say that the driver is no longer a factor in determining on track performance, but good electronics certainly help a driver to push that performance even further. Michael Schumacher is well known to be a great believer in electronic driver aids. His view is that anything that makes his car go faster is a good thing. Electronics certainly do that.

There are actually two ECU's on the car, one to cover all aspects of chassis control and another for the engine. BAR take sole responsibility for the chassis while Honda look after the engine ECU.

A huge amount of progress has been made on the electronics side of F1 in recent years. Gianni estimates that today's ECU's are at least ten times more powerful in terms of computational capacity than they were ten years ago. Not that you'd know from the outside - an ECU still looks like a rather boring little black box, betraying nothing of the information processing wizardry contained within.

All that processing power generates a lot of heat, so the ECU's need to be kept cool. They are generally located in the space around the sidepods. This is, in effect, 'dead' space, and the air intake for the radiators in the sidepods is a good source of cooling.

So what does an ECU actually do?

An ECU processes information from driver inputs, mixes it with other information about what the car is doing and comes up with the best way to bring about what the driver wants to happen.

As an example, lets go back to Jenson and his throttle. The throttle pedal is drive-by-wire, i.e. it is not directly connected to the engine. The pedal sends a signal along a wire to the ECU, which works out exactly how much power Jenson is asking for. The ECU then sends a signal to the appropriate line on the hydraulics system, which in turn causes the throttle on the engine to open the precise amount needed to give Jenson the amount of power he is looking for.

"The advantage of having an automatic throttle is we can shape the relationship between the pedal and the final throttle movement on the engine to be not necessarily linear," explains Gianni. "You can change that relationship just by changing a map on the engine ECU. This allows us to control the throttle as a function of the torque of the engine."

This means Jenson's pedal travel is a direct demand for a specific change in torque, not simply a demand for the throttle to open a certain amount on the engine.

The ECU also allows the function of the throttle pedal to be altered to suit a driver's particular style. Each driver will have the shape of his own throttle map determined by his driving style and the engine's characteristics. A driver's throttle mapping is usually sorted in the winter and left alone during the season.

The ECU performs hundreds of other calculations every second. For example, at the same time as determining the amount of torque Jenson's pedal demand produces from the engine, the ECU will work out - in accordance with the car's traction control setting - how much power to actually put through the rear wheels. But the ECU would be powerless to act on any of its clever calculations without a system that can realise the driver's demands mechanically. This is where the hydraulics kick in.

Motor neurones: Hydraulics:

A hydraulics system brings about mechanical movement using pressure transmitted through a pipe by a liquid. The technology, like so many things in F1, derives from the world of aeronautics.

The first application of hydraulic control in F1 was in 1989 by Ferrari, who used it to implement automatic control of the clutch and gear box. Now all teams use hydraulics as a matter of course.

Hydraulics work on the principle that liquids cannot be compressed - therefore any application of pressure at one end of a liquid-filled pipe (known as a line) will be transferred to the other end, where it can be used to drive a mechanical device. The hydraulics system on a Formula 1 car is pressurised by a small pump powered by the engine. Just as the alternator is driven off one end of the engine, the pump that powers the hydraulics system is driven off the other end.

"We use hydraulics because at the moment this is the most efficient way to create mechanical power with an optimised size of power source," explains Gianni. "A single, small hydraulic pump on the car is used to power all the different actuators."

Actuators are the key to hydraulic control. They are the devices that turn hydraulic pressure into actual mechanical movement.

There is a separate actuator for each hydraulic function on the car. The clutch actuator, for example, is the bit that actually makes the clutch open and close; the gear box actuator is the bit that actually makes the gear selection; the throttle actuator is the bit that actually moves the throttle on the engine... and so on.

In order to achieve the exact demand of the driver, the movement of an actuator must be extremely precise. This movement is caused by an equally precise pressure change in the line, which is effected by a servo valve. Servo valves can be electronically or mechanically operated. In the case of electro-hydraulic control, the servo valves respond to the demands of the ECU.

The basic control chain is as follows:

ECU demand - servo valve - pressure change in line - actuator movement - mechanical movement of component

Reading between the lines:

Most teams use flexible lines for their hydraulics system. BAR are one of the first teams to use rigid hydraulic lines - a cutting edge technique from the world of aeronautics. Gianni explains the rationale behind this revolutionary system:

"We decided to use rigid lines at BAR because they allow you to have a system that is much more integrated with the shape and size of the engine. In this way you can design everything as a more compact package."

As with any new technology, the difficulty is to make the rigid line system work correctly and reliably. Reliability is so important in Formula 1 these days that Gianni had to be absolutely sure the system would be worth the development effort. He's confident that it was:

"Now we have made it work, I think our rigid line system gives us a real advantage over other teams."

And that, ladies and gentlemen, is what F1 is all about.

Feature courtesy of the BAR Honda Lucky Tribe media site.