After discussing various principles of suspensions with variable dampers and springs as well as active components, mathematical models of these systems are derived. It is shown how the unknown parameters can be obtained experimentally through parameter estimation by using body accelerometers, wheel accelerometers, and suspension deflection sensors in different combinations. Experimental results are described for suspensions on a test rig and in cars driving over road surfaces. Through recursive parameter estimation these parameters can be obtained on-line in real time. Then, feedback principles are derived for controlling the damping ratio of dampers with proportional magnetic valve actuators. The potential of improvements for state space feedback in the case of road and body excitation is demonstrated by means of simulations and experiments. The different combinations of a sole variable damper or spring or both are performed. The combination of a variable damper and spring obtains the best results in nearly the same size as an active suspension system. These results were proofed experimentally on the test rig. However, the improvements were influenced considerably by the time constant of the magnetic bypass valve. Investigations show that a semi-active suspension's sum time constant should be less than 10 ms. The mathematical models are then used for fault detection and diagnosis of the damper by combining parameter estimation and parity equation methods. It was shown that an estimation of the characteristic curve of a shock absorber is possible. By a classification of the symptoms generated with parameter estimation and parity equations, an automated fault detection diagnosis is possible.
Mechatronic semi-active and active vehicle suspensions
Mechatronische, quasiaktive und aktive Fahrzeugradaufhängungen
Control Engineering Practice ; 12 , 11 ; 1353-1367
2004
15 Seiten, 16 Bilder, 4 Tabellen, 43 Quellen
Aufsatz (Zeitschrift)
Englisch
Mechatronic semi-active vehicle suspensions
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