No more skidding: Stability Control (ESP) turns 25

ESP turns 25 this year

You can thank Bosch and Mercedes-Benz if you’ve ever yanked at the steering wheel to drive around something and not ended up in a fence.

This year (2020) marks the 25th anniversary of stability control (ESP) first appearing on a vehicle. It was the Mercedes-Benz S-Class released in 1995. Until then, trying to brake, steer and drive on loose surfaces was a recipe for disaster.

The father of ESP is Anton van Zanten, the Bosch engineer who led the development of ESP and developed the yaw-rate sensor which was required to tell the ESP system when to begin working. According to Bosch, it was the partnership with Mercedes-Benz that helped to shorten the development of ESP by 25%.

But Bosch had begun working on ESP back in 1983, more than 10 years before the system would make it onto the road. The intention was to base the system off ABS (introduced in 1978) and to “flexibly adapt each wheel’s slip to improve control over the vehicle when braking in bends”.

In 1984, Bosch created a dedicated team with the aim of developing a system that would allow a vehicle to remain under control and steerable when skidding is imminent in a bend. In 1992, Bosch and Mercedes-Benz joined forces and by 1995 the system was ready and rolled out on the Mercedes-Benz Z-Class, the brand’s most powerful car.

Here’s how Bosch’s Ludger Myer described his first experience of the ESP system in 1994 – it’s the scene shown in the main image.

“It is the summer of 1994, and the air over the faded asphalt runway, which even then was a test site for the company’s engineers, is shimmering in the July heat. Our vehicle accelerates to 100 kilometers per hour before making a sharp left at full speed. What sounds like an accident in the making is, in reality, the blueprint for a test.

“As a control experiment, we switch off the anti-skid system. Anton van Zanten, the head of the ESP development project at Bosch, remains cool as a cucumber. The car picks up speed, then Zanten abruptly turns the wheel. The tires squeal; the car swerves. When it finally comes to a stop, it is obscured by smoke and the stench of burning rubber. 

“‘With the anti-skid system on, you’ll be able to take notes as we round the corner,’ van Zanten said with a wink, while he gently guides the car back to its starting position. And he’s right: we repeat the process with ESP turned on, and the outcome — at least technically speaking — is far less dramatic. We speed back up to 100 kilometers per hour before taking a sharp left. But this time, there is no sudden swerving, no smoking tires. The vehicle stays on track, the wheels perfectly in line with the steering-wheel angle, as if we had an electronic guardian angel on board.”

It wasn’t until 1997 that ESP came to the fore. Swedish automotive magazine, Teknikens Vaarld managed to flip an A-Class performing an ‘elk test’. Mercedes-Benz makes the decision to make ESP standard across its range as other car makers rush to include it in their lineups.

Then in 1998, the yaw-rate sensor that had been developed was re-made as a much smaller and longer-lasting, more reliable, less sensitive micromechanical sensor. It’s the same sensor that sits in your smartphone and allows the screen to rotate when you turn it from portrait to landscape.

By 2003, Bosch had supplied more than 10 million ESP units to car makers and now, almost every country on the planet has mandated the fitment of ESP.

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