Electronic Stability Control (ESC): How It Makes Cars Safer
Electronic Stability Control (ESC) is actually much more complex than it sounds. Since most vehicles today are being equipped with some form of stability control, it’s easy to take this new technology for granted. It’s composed of a lot more than your vehicle’s computer just performing some calculations to keep your car from exhibiting too much body roll. It controls braking, steering, lateral slippage, and traction, all in the background so that you never even know it’s there. To give you a better idea of how this new safety standard is working to make driving a bit less hazardous, we’ll run you through the workings of the ESC system, and give you some examples of vehicles that are coming with it standard.
The innovators of ESC were actually Mercedes-Benz and BMW, who introduced traction control in 1987. This is different from today’s ESC, but it was the starting point for it. Notably, it was these same two companies who introduced the first ESC systems in 1995. Basically, ESC works to monitor steering and vehicle direction. It determines the actual direction the driver wants to travel by the position of the steering wheel and compares it to the actual direction of the vehicle. If the two readings are different, it can use braking and individual wheel speeds to adjust for the difference. It finds the actual direction of the vehicle through a series of sensors that measure the vehicle’s lateral acceleration, yaw (vehicle rotation), and wheel speeds. It can also use the engine and transmission to adjust power settings if it detects a slippage.
Even with everything that ESC is capable of, it only intervenes if it detects a loss of steering control. This keeps you from fighting the system itself. When ESC was first introduced, many thought that when it kicked in it would be like someone grabbing the wheel in the middle of driving. This is actually not at all what the system does or feels like when activated. It works within the limits of the vehicle’s steering and traction abilities to assist the driver in regaining control of the vehicle. It doesn’t necessarily make decisions for you, it only helps you make the right decisions very quickly.
To break things down a little further, ESC uses four main sensors to check for vehicle control. The Steering Wheel Angle sensor is the one that determines the driver’s intentions by the position of the steering wheel. A Yaw Rate sensor measures the rotation of the vehicle (how much the vehicle is turning). Third, a Lateral Acceleration sensor measures exactly what it states – the lateral acceleration of the vehicle. And finally, a wheel speed sensor on each of the four wheels is used for both the antilock brakes and the ESC system. There are other sensors used on many systems, but these are the main four. Readings from these sensors are sent to your vehicle’s computer and processed through a control algorithm which decides when to apply the braking, reduce throttle amounts, and adjust wheel speed. Again, it doesn’t fight the driver, it only adjusts the tools the driver has to use in order to help him/her regain control of the vehicle.
There are times, however, when ESC is not much of a help. Being stuck in the snow or thick mud is one example. During these times most vehicles come equipped with an override switch to disable the ESC. Whenever you happen to find yourself in the unfortunate position of utilizing the spare “donut” tire is also a good time to switch the ESC system off, as it has no idea that the wheel size has changed and will try to make up for the difference in wheel speed.
If you’re looking for a vehicle that has ESC equipped, it won’t be long before you can go to your favorite dealership and simply pick one out. The United States government passed regulation that requires ESC on all passenger vehicles under 10,000 pounds for the 2012 model year. For the 2011 model year that same regulation required 95% of the under-10,000-pound vehicles be equipped with ESC, and 75% of the 2010 models. Some of the better vehicles to choose from that possess this new safety wonder are:
Economy Class:
Midsize and Larger:
Luxury Class:
SUV Class: