Electronic Stability Control
Newest Technologies
When drivers attempt an extreme maneuver (for example, to avoid a crash or because a curve’s severity has been misjudged), they may experience unfamiliar vehicle handling characteristics as the vehicle nears the limits of road traction. The result is a loss of control. This loss usually results in either the rear of the vehicle "spinning out," or the front of the vehicle "plowing out ."
A professional driver, with sufficient road traction, could maintain control in an extreme maneuver by using various techniques, such as countersteering (momentarily turning away from the intended direction). It would be unlikely, however, for an average driver to properly apply countersteering techniques in a panic situation to regain vehicle control.
Spinning Out
Above, two vehicles, one traveling behind the other, have entered a left curve that is too extreme for the speed they are traveling. The rear of the ESC-equipped lead (blue) car begins to slide (also known as "spinning out" or "oversteering"). In the ESC-equipped lead (blue) car, the ESC system immediately detects that the vehicle’s direction is changing more quickly than appropriate for the driver’s intended direction. ESC momentarily applies the right front brake (see arrow) to alter the direction of the vehicle back to the correct path. The rear of the non-ESC equipped trailing (red) car also begins to slide or spin out as it enters the left curve. However, in the case of the non-ESC equipped vehicle, it continues to spin out, and ends up off the road.
Plowing Out
Above, two vehicles, one traveling behind the other, have entered a left curve and have neared the limits of road traction. The front of the ESC-equipped lead (blue) car begins to slide (also known as "plowing out" or "understeering"). In the ESC-equipped (blue) lead vehicle, the ESC system immediately detects that the vehicle’s direction is changing less quickly than appropriate for the driver’s intended direction. ESC momentarily applies the left rear brake (see arrow) to alter the direction of the vehicle back to the correct path. The front of the non-ESC equipped trailing (red) car also begins to slide or plow out as it enters the left curve. However, in the case of the non-ESC equipped vehicle, it continues to plow out and runs off of the road.
HOW ESC WORKS
Electronic Stability Control (ESC) uses automatic braking of individual wheels to prevent the heading from changing too quickly (spinning out) or not quickly enough (plowing out). ESC cannot increase the available traction, but maximizes the possibility of keeping the vehicle under control and on the road during extreme maneuvers by using the driver’s natural reaction of steering in the intended direction.
ESC happens so quickly that drivers do not perceive the need for steering corrections. If drivers do brake because the curve is more or less sharp than anticipated, the system is still capable of generating uneven braking if necessary to correct the heading.
ESC systems exist under many trade names, including Vehicle Stability Control (VSC), Electronic Stability Program (ESP), and Vehicle Stability Enhancement (VSE).
