ISBN 9783843936385

978-3-8439-3638-5, Reihe Ingenieurwissenschaften

Mahmoud Ahmed
Robust and Preview Control for Vehicle Semi-Active Suspension

197 Seiten, Dissertation Universität der Bundeswehr München (2017), Hardcover, A5

Zusammenfassung / Abstract

Vehicle suspension is one of the main elements inside a vehicle that mostly affects its entire dynamics regarding both ride comfort and road holding. The semi-active suspension system with its varying damper characteristics is considered to be the best compromise between cost and performance. The aim of this thesis is to present control design approaches for improving the performance of vehicle suspension with respect to both ride comfort and road holding. The current state of the art is extended by this thesis with the following contributions:

A Non-Model based Adaptive Control (NMAC) algorithm has been proposed for generating road profiles using an electro-hydraulic servo system. This control algorithm can be implemented without having a plant model to meet the adaptability requirement.

A robust gain-scheduled control approach is introduced. Two linear H-infinity controllers are computed for both ride comfort and road holding under considering the minimum and maximum limits of the chassis mass. The two controllers are coupled together to cope with the chassis mass variation.

A preview controller based on Fast Fourier Transform (FFT) is proposed, such that the road profile in front of the vehicle is scanned using LIDAR sensors. The control functions of the vehicle suspension are obtained for different road profiles by solving a mixed-integer optimization problem based on Model Predictive Control (MPC) offline. These functions are saved in lookup tables to be recalled during the vehicle motion online.

Another preview controller is presented, such that the control laws are derived based on frequency partitioning of the chassis acceleration and tire load spectra. A simulated vehicle model is run online during the vehicle motion. For each frequency partition, a control law that achieves the optimal performance in the selected partition is applied.

The obtained results indicate the improved performance of the proposed controllers that can be used in the future for enhancing the overall vehicle dynamics for Global Chassis Control (GCC).