Effect of the suspension structure on equivalent suspension parameters

Abstract

This paper examines the uncertainties in modelling a real suspension system that are due to the effect of suspension linkage layout (or structure) on the equivalent suspension parameters of a corresponding mathematical model. In most research on active suspension systems, a quarter-car model of two masses is very often used. However, without considering the influence of the suspension kinematic structure, the simple model may not be as effective as might be expected because of the uncertainties in the suspension parameters. Two sets of identified parameters for different suspension systems are compared to show the effect of suspension structure on the equivalent parameters. The relationships between specific parameters and changes in certain suspension linkage layouts are also investigated. The benefits of the parameter identification are demonstrated in the process of designing two active systems (one using a sky-hook control law and the other using a sliding mode control technique). The results show that suspension structure has a strong effect on the equivalent suspension parameters and this relationship becomes more important as the structure of suspension increases in complexity. The advantage of the identification process is crucial in designing both linear and non-linear active suspension systems.