A servo-driven dry-friction damper is a potential alternative to a traditional car suspension viscous damper. The friction damper is semi-active: damping is controlled without energy introduction into the system and hence the power required is much smaller than fully active systems. Models of the hydraulically actuated friction damper and of the vehicle have been developed and system performance predicted using simulation. An experimen-tal validation of the simulation study has been under-taken on the various subsystems and on the whole system. The model of the hydraulic drive describes the measured behavior very well. The leakage model employed for the valve is effective in predicting the actual pressure gain. The critical phenomenon of the air in the oil, which limits the bandwidth of the system, was taken into account by reducing the effective bulk modulus of the fluid. It has been shown that a reduction in chassis acceleration can be obtained at the cost of an increase in working space. The control algorithm has been shown to have good robustness properties. The semi-active system model works reasonably well in terms of predicting time domain response. Its frequency response matches the experimental data well up to the chassis resonance; at higher frequencies the results are over-estimated because of the limitations of the car model and the use of a linear model for the remaining (conventional) dampers. The acceleration time re-sponses are also accurately predicted. The major problem that arose in the course of the experimental work was the limited pressure control system bandwidth at low hydraulic supply pressure. This was unexpected from the initial simulation studies and to achieve a (barely satisfactory) bandwidth necessitated an increase of the supply pressure with a subsequent increase of the power dissipated. The trade-off between power consumption and bandwidth is a serious problem and will be addressed in further studies by consideration of alternative pressure modulation schemes.
A controlled friction damper for vehicle applications
Ein Stoßdämpfer mit geregelter Reibung für Fahrzeugradaufhängungen
Control Engineering Practice ; 12 , 4 ; 431-443
2004
13 Seiten, 24 Bilder, 1 Tabelle, 24 Quellen
Aufsatz (Zeitschrift)
Englisch
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