Drive behind the horsepower

Adding computing power to the horsepower in cars is a relatively new chapter in the century old story of the automobile industry. It is interesting to note that processors that had enough computing power to run hundreds of car engines simultaneously, have been available for decades.

Intriguingly, government legislation was the catalyst that paved the way for computer chips to take total control over the car engine. Until recently, the rigorous demands of the industry could be met through mechanical innovations. It was only with the introduction of strict emissions restrictions and tight legal demands on fuel efficiency, that it became necessary for car makers to use computer chips to regulate the mechanics and chemistry of the car engine in such fine detail, that mechanical improvements alone could not achieve the level of efficiency that was necessary.

In almost every car that is made today, dozens of sensors monitor the function of every component, from coolant temperature to the fuel-air combustion ratios and fuel pressure to the amount of oxygen in the exhaust. The data that is gathered by these sensors are fed into the most powerful computer in the car – the Engine Control Unit or ECU. The ECU performs millions of calculations including looking up values in tables, calculating the results of long equations to decide on the best spark timing and determining how long the fuel injector is open to ensure the lowest emissions and best mileage.

A modern ECU might contain a 32-bit, 40-MHz processor backed by about 1 MB of memory. It is not an exaggeration to say that a desktop computer these days is quite literally a hundred times more powerful. But the functions of an ECU are very simple. Unlike a PC, they don't have to deal with processor intensive tasks such as multimedia. The instruction set of an ECU is streamlined to handle a finite set of comparatively simple functions. In most modern cars, functions of the ECU include firing the spark plugs, opening and closing the fuel injectors – which is what 'Electronic Fuel Injection' is all about – and turning the cooling fan on and off.

The ECU is supported by other electronic components in a way that is not very different to the functions performed by a motherboard in a PC. These additional components help the ECU communicate with other digital as well as analogue components of the system including the sensors and regulators. They usually communicate with the ECU at speeds of up to 500 kilobits per second. This speed is becoming necessary because some modules communicate data onto the bus hundreds of times every second. The information that is exchanged between the ECU and its sensors and other components include details about any faults that occur in the various components of the car. These are sent to a central module, which stores the faults which are then sent to an off-board diagnostic tool. This can make it easier for technicians to diagnose problems with the car when it is taken for a service or repairs.

While the ECU has helped make cars more economical and efficient, there are also processors onboard that work fulltime to keep you safe. They will stabilise your car as you swerve suddenly to avoid an obstacle on the road. Any car that has Anti-lock Braking System (ABS) will have sensors measuring the grip on each tyre, an on board computer which knows the speed of the car, calculates the optimal breaking pressure for each wheel. Another on board computer will control the steering – if the car is equipped with "Electronic Stability Control" – to make sure that it doesn't spin out of control. A separate set of processors are dedicated to calculate the best time to inflate the airbags – or whether that is necessary in the first place – in case of a sudden impact.

Satellite navigations systems are sometimes available embedded on the dashboard, but more often they can be bought as stand alone portable systems. Even though this technology is not available for civilian use in Sri Lanka yet, in many other countries they will precisely guide you to a specified destination using clear voice prompts and visual displays. Most are sophisticated enough to be coupled with a mobile phone to obtain real-time traffic information which helps users avoid congested routes and estimate travel times with surprising accuracy that they almost seems magical.

So the question I posed last week still remains open; do we have the technology to build cars that will drive themselves. As you wait another week for the answer, write in to technopage@gmail.com and tell us what you think.