We have all seen the TV commercials where the family’s life was saved by automatic stability control. This scene is usually a wet rainy night, and a boulder falls off the side of a mountain onto the road surface. This stability control commercial shows the driver skillfully avoiding a potential accident by yanking on the steering wheel.

Many people see these commercials and think that this is pretty interesting automotive technology. But what they may not know is that these systems are mostly operated and controlled by antilock brake technology. Although keep in mind when you are buying a new car that various types of stability control systems are found on today’s vehicles.

Just as on traction systems stability controls are based and linked to the ABS system and on some vehicles they are linked to both the brake and electronic suspension systems. A few expensive vehicles offer a driver controlled switch that allows the traction control system to be disabled without turning off the stability control features.

Automatic stability control operation

Again, the systems will differ between vehicle manufacturers, but most stability control systems will momentarily apply the disc brake pads at one wheel to correct a oversteer or an understeer condition. The control unit receives signals from the speed sensors plus some units will have a lateral acceleration or G-force sensor. The latest releases might be equipped with a steering angle sensor.

Understeer is best described as a condition where the automobile is slow to respond to driver steering input. Oversteering is like fish tailing or when the rear of the vehicle becomes out of alignment with the front axle. If the automatic system detects over or under steer while the vehicle is negotiating a turn brake pressure is applied to the appropriate rear caliper.

Relying on the input from the sensors and the computer programming the system calculates if the vehicle is going exactly in the direction in which it is being steered. If there is a difference between what the drivers asking for and what the vehicle is doing the system will ideally correct this situation by applying one of the brakes in the four corners.

Stability control advanced Systems

This advanced control system will use the steering angle to calculate the path the driver has selected. It will then monitor the lateral sensor and the G-forces on the vehicle to measure where the vehicle is actually going.

Stability safety control offers assistance when the automobile is braking, coasting or during heavy acceleration. If emergency braking is applied and over steer or understeering is senced increased brake fluid pressure is sent to the caliper needed to maintain driver control.

It took us a while to get used to antilock brake systems and traction control systems. But they have been proven to provide a safer driving experience. These automatic stability control systems show the same promise to improve automobile safety. Over time as automotive diagnosis and technologies improve, we may even see them as government mandated standard safety equipment.