Multi-objective Optimization of Low-floor Minibus Suspension System Parameters

Goran Šagi (PROSTEP AG, Adolo7 d.o.o.), Zoran Luli (PROSTEP AG, Adolo7 d.o.o.) and Josip Stjepandic (PROSTEP AG)

This paper describes improvements and interaction of multi-objective optimization and simulation tools for the analysis of suspension system kinematics and vehicle dynamics in the conceptual phase of low-floor minibus development. Achieving optimum parameters of the vehicle at this stage of development reduces the possibility of wrong solutions or concepts. Suspension system development process is a challenging task due to the existence of many influential parameters, complex and often conflicting objectives related to stability, handling, ride comfort and other aspects of vehicle dynamics. Also this is a multidisciplinary task which presents a computational and modeling challenge. This task has three fundamental steps: multi-objective problem definition, multi-objective optimization process and multi-criteria decision making. In this research, the focus is on the first two steps.

Variables – Positions of suspension system hard points


The definition of design variables, objectives and constraints is necessary in the problem definition process. After that in optimization process, the goal is to determine optimal suspension system parameters of low-floor minibus using newly developed optimization model, based on evolutionary algorithms and vehicle dynamics simulations. This paper gives a contribution to the validation of simulation models, the fine adjustment of optimization algorithm parameter values (population size, probability of mutation, crossover or selection, etc.), the analysis of convergence of an evolutionary algorithm, the comparison of the results obtained by evolutionary algorithms with results of other multi-objective optimization methods and the implementation of proposed optimization model for determining optimal suspension system parameters of low-floor minibus.