The elk test and preventing skidding accidents

The development of the electronic stability program (ESP) by Bosch was a milestone on the path to accidence-free autonomous driving. The 25-years old ESP can prevent up to 80 percent of all skidding accidents.

Especially when roads are wet or icy, when evading unexpected obstacles such as animals on the road, and also when driving into a bend too fast, the trademarked ESP intervenes. It or one of the competing solutions by other Tier1s combines the functions of the antilock braking system (ABS) and the traction control system (TCS), but can do considerably more. It also detects vehicle skidding movements, and actively counteracts them. Most of such anti-skid systems use CAN to communicate between the electronic control units (ECU).

The anti-skid system uses information about vehicle dynamics to detect whether the car is heading in the direction the driver is steering. If there is a discrepancy between these two factors, it takes action. Sensors help compare steering angle and vehicle trajectory 25 times a second. If the two diverge, the anti-skid system reduces engine torque and brakes individual wheels. In this way, the system helps the driver prevent the vehicle from breaking away.

The story behind this achievement is a long one. It started in the 1980s with initially independent efforts by Bosch and Daimler-Benz to achieve more vehicle stability. From 1992 until market launch, experts from the two companies worked together. The legendary elk test of 1997 helped the system achieve a breakthrough: during tests for a Swedish automotive magazine, a Mercedes Benz A-class tipped over when making an abrupt evasive maneuver. Mercedes-Benz responded by making ESP standard equipment. Since that time, more and more vehicles of many different automakers have adopted the anti-skid system.

Fewer accidents, fewer injuries, fewer fatalities – legislators have also recognized the benefits of the anti-skid system and made it a mandatory feature of vehicles in many parts of the world. In the EU, the mandating process was gradual. From November 2011, it was initially mandatory for new passenger-cars and commercial-vehicle types, and from November 1, 2014, for all newly registered passenger cars and commercial vehicles. And also in Argentina, Australia, Brazil, Canada, China, Ecuador, Israel, Japan, Malaysia, New Zealand, Russia, South Korea, Turkey, and the United States, the anti-skid system is either legally mandated or a self-imposed commitment.

“ESP has taken road safety to a new level,” said Harald Kroeger, member of Bosch’s board of management. The German company offers customized ESP systems for all powertrain types, from combustion engines to electric motors, and for vehicles of all kinds, from micro cars to commercial vehicles. Even for motorized two-wheelers, the company has developed a kind of anti-skid system, the MSC motorcycle stability control that was launched in 2013.

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