Investigation of the performance of hyDROPneumatic slow active suspension systems for motor vehicles

This thesis contains theoretical and experimental studies of thehyDROPneumatic vehicle suspensions. Depending on the well-known quartercar model, first techniques for modeling the vehicle and road surface arediscussed. The standard linear and nonlinear analysis methods are reviewed.The performances of the proposed suspension systems are compared withboth the baseline passive system and an idealized fully active suspensionone.Secondly, the analysis and the descriptions of a hyDROPneumatic suspensionsystem is studied based on the existing hyDROPneumatic passive suspensionsystem of CITROEN-BX type. Predicted results for this existinghyDROPneumatic passive suspension system are generated in terms of theI.S.0. weighted body acceleration; dynamic tyre load, and suspensionworking space.Thirdly, the control laws for active suspension systems using the full andlimited state feedback gains are generated. The controller design for theproposed suspension is based on limited state feedback, and the NelderMead simplex algorithm is used to calculate the gains to optimise theperformance index. The effects of the control law time delay, and the payloadvariations on the active suspension system performance are discussed.Fourth, two versions of slow active (limited bandwidth) hyDROPneumaticsuspension. systems are studied and developed. By using existinghyDROPneumatic suspension system components, that taken off Citroen-BXtype, it is capable to form a practical slow active hyDROPneumatic suspensionsystem. By inserting a PlO controller into the error correction signal with thesuspension working space feedback signal, a self leveling effect can beobtained,Fifth, the characteristics of the practical hyDROPneumatic passive suspensionsystem (i.e. gas spring stiffness and throttling valve-damping coefficients) aremeasured, and the quarter car (single wheel station) test rig is designed toevaluate the performance of the hyDROPneumatic passive suspension systemwhich taken off CITROEN-BX type. A controller is designed to drive thepractical slow active hyDROPneumatic suspension system using Labviewsoftware with the pc mIc, and the data acquisition card. Finally, the theoreticaland the experimental results of the slow active hyDROPneumatic suspensionsystem are reasonable and encourage continuing the work in this field withthe limited state feedback gains.