Semi-active Suspension & Adaptive Damping

[ARTICLE IS WORK IN PROGRESS]

The key difference between semi-active and active suspension is such that:

• • Fully active suspension: generates and dissipates energy

  • Semi active suspension: only dissipates energy

Adaptive Damping Systems (ADS) as a part of semi-active suspensions adjust the amount of damping force for different conditions including:

• • vehicle speed

  • vehicle cornering attitude (steering angle, steering rate)

  • vehicle longitudinal accelerations (longitudinal G, braking, throttle)

  • road morfology (accelerations, frequencies)

Several patented terms and technologies are in wide use in industry:

• • Magnetic Ride Control - Cadillac

  • Electronic Air Suspension (EAS) - Range Rover

  • Active Body Control (ABC) - Mercedes Benz

  • Active Roll Control - TRW AUtomotive

  • Dynamic Body Control - Delphi Automotive

  • Magne Ride - Delphi Automotive

Typically cars that offer ADS have selectable "modes" for the driver to choose from. Audi for example offers a Sport/Comfort button, whereas supercars like McLaren have a Handling mode with selectable Normal/Sport/Track settings.

Typically, damping force can be electronically controlled in two ways:

• • by varying the opening of the valve orifice that controls oil flow: Continuously Controlled Electronic Suspension (CES)

  • by making a fluid more or less viscous: Magneto-Rheological dampers (MR)

CES or MR systems are used as OEM parts or aftermarket. For example shown below is a system provided by the german manufacturer KW.

Continuously Controlled Electronic valves are mostly manufactured and sold to other suppliers by Ohlins

Literature:

Gaspar, Szabo - Active Suspension in Integrated Vehicle Control (intechopen.com)

Guglielmino, Sireteanu, Stammers - Semi-Active Suspension Control (Springer ISBN 978-1-84800-231-9; £129 hardback)

Kashem, Nagarajah - Vehicle Suspension Systems and Electromagnetic Dampers (Springer ISBN 978-981-10-5478-5 £129 hardback)

Koch - Adaptive Control of Mechatronic Vehicle Suspension Systems

Liu, Gao, Li - Handbook of Vehicle Suspension Control Systems (IET ISBN 9781849196338)

Mustafizur - Simulation of Preview Controlled Active Suspension for Vehicles (Lambert ISBN 9783659284830 £55 via blackwells.co.uk)

Savaresi - Semi-Active Suspension Control Design For Vehicles

Sun, Gao, Shi - Advanced Control For Vehicle Active Suspension Systems (ISBN 978-3-030-15785-2; £120 hardback)

Yasser - MPC-on-chip in Application to Automotive Active Suspension Systems (Lambert Academic Publishing; Blackwells.co.uk)