In this paper, the authors have investigated the performance of semi-active vehicle suspensions which are based upon smart fluid dampers. The investigation has been essentially numerical but the mathematical models of the smart fluid dampers have been derived from an industrial scale experimental facility. A number of interesting conclusions have emerged: 1) Under open loop conditions, smart dampers are not well suited to vehicle suspension applications. This arises from the typical form of the force/velocity characteristic of a smart damper which resembles that associated with a Bingham plastic. The presence of a yield stress, which must be overcome before motion can occur, is not conducive to the efficient operation of a vehicle suspension. 2) If force feedback control is applied then the force/velocity characteristics of the smart damper can readily be linearised. In this way the damper can be made to behave like a controllable viscous device. In the numerical simulations of a quarter car model it has been shown that there is excellent agreement between the ER device under feedback control and the corresponding idealised passive device. This result holds under both sinusoidal and non-sinusoidal excitations and over a range of damping rates. The approach could be useful for vehicle suspension prototyping trials. 3) Within the available control envelope, the ER damper under feedback control can be made to operate in a similar fashion to a skyhook damper. Skyhook damping can be improved by augmenting the system with passive damping, resulting in the modified skyhook control strategy. For this latter strategy there is very good agreement between the behaviour of the ER device and that of its idealised counterpart under sinusoidal excitation. For non-sinusoidal excitation it has been shown that significant performance gains can be achieved over a conventional passive suspension. To extend this result to MR-based semi-active suspensions a numerical study suggested that larger time constants do not significantly affect the response. However, further work is required to validate these results. This will require more accurate representations of road disturbances together with validated models of a suitable MR damper. Work is currently proceeding on both aspects. 4) It was shown that while the on/off control of a smart fluid damper will work effectively under sinusoidal excitation, the approach breaks down under non-sinusoidal excitation. This result underlines the usefulness of the continuous feedback control strategy proposed by the authors. Future work will focus on modelling and control of MR dampers using the same techniques followed by an experimental investigation along the same lines as this numerical study.
Semi-active vehicle suspension using smart fluid dampers: a modelling and control study
Halbaktive Fahrzeugfederung mit intelligenten Flüssigkeitsdämpfern: Untersuchung von Modellierung und Regelung
International Journal of Vehicle Design ; 33 , 1/3 ; 76-102
2003
27 Seiten, 32 Bilder, 1 Tabelle, 26 Quellen
Article (Journal)
English
Fahrzeugfederung , Stoßdämpfer , Fahrzeugdämpfung , Fahrverhalten , Fahrzeugfahrwerk , Anwendung im Fahrzeugbau , magnetorheologische Flüssigkeit , intelligenter Werkstoff , elektrorheologische Flüssigkeit , Schwingungsregelung , mechanische Schwingung , theoretische Untersuchung , Systemantwort , mathematisches Modell , Regelungstechnik , Regelkreis , Pkw (Personenkraftwagen)
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