Raymond D. Young / | March 15, 2006 00:00
The different letters of your car's stability control
Over time, cars have progressed quite rapidly. With the inclusion of new technologies cars of today are more powerful, fuel efficient, and more dependable. Top speeds of new cars have also increased, thereby increasing the chances of mishaps.
Some manufacturers have not overseen this possibility. As their cars improve on speed, acceleration, and handling, they have also devised a way on how to control the car's behavior in the event the car's limits have been exceeded. These technologies or features are loosely termed as "Electronic Stability Control".
As the term suggests, it is a computer-governed device used to improve a vehicle's handling, in particular when the car's limits are reached, which may lead to the driver losing control. As a brief history, Bosch was first to develop and deploy an Electronic Stability Program (ESP) that was used by Mercedes Benz starting 1995. Since then, many manufacturers have come up with their own version of an Electronic Stability Control, hence the difference of terms of the same concept per almost every manufacturer.
Although implementations may differ per manufacturer, ESC compares the driver's steering and braking inputs, versus that of the actual vehicle's response parameters, such as lateral acceleration, rotation and individual wheel speeds. If needed, ESC will try to regain traction on the affected wheel by either applying brake to the affected tire or reduce engine power. With this procedure, ESC is sometimes integrated to other vehicle safety systems such as ABS (Anti-Lock Brakes), Traction Control, All-Wheel Drive and other similar systems.
It must be stressed that ESC cannot prevent a collision, it is just a tool for the driver to regain control of the car during slippery situations or when the car's limits are exceeded. In general, ESC will prevent any occurrences of understeer (i.e. car does not respond to steering input and will instead move forward) and oversteer (due to excessive power in the rear wheels, car tends to steer at a more increased angle than the driver's input).
Majority of the cars offered in the local market today have implementations of Electronic Stability Control. For the compact sedan category, Honda was the first to introduce this feature into the segment via their VSA (Vehicle Stability Assist). Variants of BMW, Mercedes-Benz, Audi, and other popular European marques also have these by default.
A similar technology but of a different implementation are mostly found on all wheel drive systems. Nissan's ATTESA-ETS PRO (Advanced Total Traction Engineering System for All - Electronic Torque Split), which debuted in the world-renowned Nissan Skyline GT-R, does not provide vehicle stability by braking or reducing power to the affected wheel but rather it does the opposite. It applies more torque to the wheel that has established traction, thereby increasing the cornering limits of the vehicle. Mitsubishi also has a similar system which is termed as AYC (Active Yaw Control) or ACD (Active Center Differential). Used in the Lancer Evolution series, the former gives more torque to either the left or right wheel which has more grip, while the latter distributes torque between the front and rear wheels via the preset settings selected by the driver.
The aforementioned technologies are devised to give more driver confidence during spirited driving or high-speed maneuvers. Keep in mind, however, that these devices are not life saving but rather keeps the driver aware of every driving situation. As mentioned, if the car's limits are exceeded there would be no ESC or any safety alphabet that could save you. Remember, safe, defensive, and sensible driving is still a must even if you drive a vehicle equipped with such technologies.