Active Suspension

The active suspension and adaptive suspension/semi-active suspension are types of automotive suspensions that controls the vertical movement of the wheels with an onboard system, rather than in passive suspensions where the movement is being determined entirely by the road surface.

This technology allows car manufacturers to achieve a greater degree of ride quality and car handling by keeping the tires perpendicular to the road in corners, allowing better traction and control. An onboard computer detects body movement from sensors throughout the vehicle and, using data calculated by opportune control techniques, controls the action of the active and semi-active suspensions. The system virtually eliminates body roll and pitch variation in many driving situations including cornering, accelerating, and braking.

While adaptive suspensions only vary shock absorber firmness to match changing road or dynamic conditions, active suspensions uses some type of actuator to literally raise and lower the chassis independently at each wheel. Manufacturer brand names for adaptive suspensions include Airmatic suspension (Mercedes-Benz), Adaptive Damping, and Road-Sensing Suspension. Active suspensions include Active Body Control (Mercedes-Benz) and Active Roll Stabilization (BMW). For instance, in the 2005 model year, the Mercedes-Benz S55 AMG has the Active Body Control active suspension, while the Mercedes-Benz S430 comes standard with the Airmatic adaptive suspension and has Active Body Control as an option.

Active suspensions can be generally divided into two main classes: pure active suspensions and adaptive/semi-active suspensions.