Active suspension
These technologies allow car manufacturers to achieve a greater degree of ride quality and car handling by keeping the chassis parallel to the road when turning corners, preventing unwanted contacts between the vehicle frame and the ground (especially when going over a depression), and allowing overall better traction and steering control.
An onboard computer detects body movement from sensors throughout the vehicle and, using that data, 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.
To achieve the same level of stability as the Skyhook theory, the vehicle must contact the ground through the spring, and the imaginary line with the damper, as in Figure 2.
The drawbacks of this design are high cost, added complication and mass of the apparatus, and the need for frequent maintenance on some implementations.
Sensors continually monitor body movement and vehicle ride level, constantly supplying the hydraulic height correctors with new data.
This system performed remarkably well in straight ahead driving, including over uneven surfaces, but had little control over roll stiffness.
Colin Chapman developed the original concept of computer management of hydraulic suspension in the 1980s to improve cornering in racing cars.
Lotus fitted and developed a prototype system to a 1985 Excel with electro-hydraulic active suspension, but never offered it for sale to the public, although many demonstration cars were built for other manufacturers.
Sensors continually monitor body movement and vehicle ride level, constantly supplying the computer with new data.
Almost instantly, the servo-regulated suspension generates counter forces to body lean, dive, and squat during driving maneuvers.
Williams Grand Prix Engineering prepared an active suspension, devised by designer-aerodynamicist Frank Dernie, for the team's Formula 1 cars in 1992, creating such successful cars that the Fédération Internationale de l'Automobile decided to ban the technology to decrease the gap between Williams F1 team and its competitors.
[8][9] Active anti-roll bar stiffens under command of the driver or suspension electronic control unit (ECU) during hard cornering.
They consist of a solenoid valve which alters the flow of the hydraulic medium inside the shock absorber, therefore changing the damping characteristics of the suspension setup.
[23][24] This implementation is currently used industry-wide by a number of manufacturers, provided by Monroe Shock Absorbers called CVSAe, or Continuously Variable Semi-Active electronic.
DampTronic provides three selectable driver settings that can also interact with the Vehicle Dynamics Control technology to modify the transmission's shift points.
The fast reaction of the system (milliseconds) allows, for instance, making a softer passing by a single wheel over a bump in the road at a particular instant in time.
