The Relative Performance Capabilities of Passive, Active and Semi-Active Car Suspension Systems

Abstract

Based on the well-known quarter car representation of the automobile suspension design problem, pdomnce parameters relating to passenger discomfort, working space and tyre load variability are generated for passive, active and semi-active suspension systems. Active systems of two types having different hardware implications are considered, and linear optimal control theory is used in each case to derive a good set o control law parameters. The semi-active systems studied have control laws based on the fully active systems, but are capable only of dissipating energy, so that where the corresponding active system would be acting as an energy supply, the semi-active system switches off Practically realizable switching dynamics are assumed in the calculations. Results for all the systems, for one road surface roughness and vehicle speed, are generated in a form which allows comparison between systems of diffient types which have equal suspension working space requirements. The wider implications of the results are discussed, and far-reaching conclusions about the relative capabilities and design features of passive, active and semi-active systems are drawn.

Observer Based Optimal Control of MR Dampers

“…The dynamics of the state estimation error are then given by (11) Where L is the observer gain, and (12) If the eigen-values of have negative real parts then as . Hence, as .…”

“…Scientists have been studying the vibration theory since the first quarter of the twentieth century [5][6][7][8][9][10][11][12][13][14][15][16][17]. Some of the earliest research was done by Timoshenko [17] and Den Hartog [5] who described the primary solutions to vibration problem of the engineering structures.…”

“…For the large excitation bandwidth the performance will decrease. Due to this passive systems are optimal for specific conditions [12].…”

“…The performance of semi-active systems almost reaches that of active systems while keeping the weight, cost and complexity of the system similar to passive systems [7,12]. Semiactive systems provide a means to control energy storage and/or dissipation.…”

Optimisation of an Active Suspension Force Controllerusing Genetic Algorithm for Random Input

“…The spectral characteristics of road roughness have been measured extensively for various types of roads, from high quality highways to poorly maintained secondary roads [17][18][19] . The measurements are analysed in terms of wave-number spectra, or power spectral density where the independent variable is distance rather than time.…”