Development of semi-active truck suspension

Within the EC project Copernicus SADTS (Semi-Active Damping of Truck's Suspension and Its Influence on Driver and Road Loads) the semi-active suspension for Liaz truck prototype is being developed. The objective is to decrease the dynamic road-tyre forces in order to reduce the road damage. It was necessary to develop a suitable truck prototype, its simulation model, different control concepts and to implement the semi-active suspension. The paper describes the development stages and the so far achieved results. The full mathematical model was the basis for simplified models for control designs and served as a reference model for comparison of different control concepts. The spatial three dimensional simulation model has been developed and verified. The base model includes also the reference inputs of excitation and the different criteria for performance evaluation. The purpose of the model was to investigate the vertical dynamics though with the influence of antisymmetry of uneveness and lateral motion. A number of different control concepts have been considered. Possible suitable control concepts have been selected from existing classical as well as advanced control design methods. Also several within this project newly developed approaches have been added. There have been considered the control concepts of simple approaches (sky hook), classical approaches (LQR), multi-objective multi-parameter optimization (MOPO), fuzzy and neural networks, robust control design. The newly developed control concepts are ground-hook and combination sky/ground-hook, robust multi-objective optimization based on Taguchi approach, fuzzy control based on optimization, structural approach (separate control of frame and cabine suspension). The performance criteria for evaluation have been road forces, driver's seat and load accelerations, robustness against change of parameters. The comparison has been done on the simulation model in SIMPACK program package connected with MATLAB/SIMULINK. Very promising results have been achieved up to now by combination of sky-ground hook and by the classical LQR control. The evaluation of other concepts is still in progress. Hardware and field tests are scheduled for 1997.