Definition: A computerized hydraulic suspension system that uses hydraulic "actuators" instead of conventional springs and shock absorbers to support the vehicle's weight. A "chassis computer" monitors ride height, wheel deflection, body roll and acceleration to control ride and body attitude. Bumps are sensed as they are encountered, causing the computer to vent pressure from the wheel actuator as the wheel floats over the bump. Once the bump has passed, the computer opens a vent that allows hydraulic pressure to extend the actuator back to its original length. The only production active suspension was used on the Infiniti Q45.