TLDR: Active suspension is a type of car suspension that uses a control system to control the movement of the wheels and axles. It improves ride quality and handling by keeping the tires perpendicular to the road and preventing unwanted contacts between the vehicle frame and the ground.
Active suspension is a type of automotive suspension that is different from the conventional suspension found in most cars. Instead of relying solely on large springs to support the weight of the vehicle and dampen the movement of the wheels caused by the road surface, active suspension uses an onboard control system to actively control the vertical movement of the wheels and axles relative to the chassis or vehicle frame.
There are two classes of active suspension: true active suspensions and adaptive or semi-active suspensions. True active suspensions use actuators to independently raise and lower the chassis at each wheel, while adaptive or semi-active suspensions vary the firmness of the shock absorbers to match changing road conditions.
Active suspensions allow car manufacturers to achieve a greater degree of ride quality and car handling. By keeping the tires consistently perpendicular to the road when turning corners, active suspension prevents unwanted contacts between the vehicle frame and the ground, especially when going over bumps or depressions. This improves traction and steering control, resulting in better overall handling.
An onboard computer detects body movement from sensors throughout the vehicle and uses that data to control the action of the active and semi-active suspensions. This virtually eliminates body roll and pitch variation in many driving situations, including cornering, accelerating, and braking.
Active suspension can also be used in commercial vehicles such as buses to temporarily lower the vehicle's floor, making it easier for passengers to board and exit the vehicle.
In summary, active suspension is a type of car suspension that uses a control system to actively control the movement of the wheels and axles. It improves ride quality and handling by keeping the tires perpendicular to the road and preventing unwanted contacts between the vehicle frame and the ground.