Nowadays we’re starting to see some form of electronic stability control in most of the cars for sale. From a feature that used to be reserved for only the cream of the crop of cars, even the entry level models in our market receive this feature that some are deeming to be as important as ABS and airbags when it comes to safety. On a personal note, I am a stronger advocate of learning to handle a car without these aids, although for the vast majority of the population, these systems have become a safety net.
These systems were first introduced by Mercedes-Benz, a little over 20 years ago. It came about after a young test engineer had an accident when he skidded across a patch of ice, and from there he felt that such situations could be avoided or prevented with some mechanical intervention. It just so happened that he had transferred to the electronics group from engine development, giving him access to some of the more crucial systems that ESP revolves around.
Much like how ABS relied on wheel speed sensors to determine when a wheel was locked up, ESP also relies on wheel sensors. But where the convention was to have one wheel speed sensor on the front and one on the rear, ESP required all four wheels to have individual speed readings for the system to function accurately. Similarly the electronic application of brakes had to be individual for each wheel as well.
The system operates depending on what state the car is in: whether it’s understeer, neutral, or oversteer. These basic concepts can be thought of as the front tyres losing grip, all tyres maintaining contact, and the rear tyres losing grip respectively. How ESP works is it slows the wheels down enough to maintain grip (in the case of a rear wheel drive spinning the tyres), and it also brakes a specific wheel to generate a turning moment which brings the car back on course.
The physics and technical aspects of the system are a little difficult to explain in a short article, but the gist is this: Mercedes-Benz developed the earliest form of electronic stability control systems, and through the last 2 decades every manufacturer has slowly emulated and adopted the same principles to varying degrees of success. But it would not have become a standard were it not for the 3-pointed star, and we owe them a debt of gratitude- whether you believe ESP is necessary or not.
