Modelling, control and design of heavy duty suspension systems

The design of suspension systems for off-highway vehicles covers a specific field of automotive industry. During the last years, due to the working conditions in agricultural environments, there have been an increasing demand in power capabilities, loads and driving speeds of heavy duty vehicles. In this way the industrial design and consequently the research activity present a big potential of improvement. This paper describes the development, modeling and testing of suspension systems and control algorithms for heavy vehicles. The main targets of this activity, currently under development, consist in the study of the dynamical behaviour of agricultural tractors and the design of a cost-effective industrial solution. The work is structured in different steps: the definition of the project requirements (also by consultations with manufacturers), the modeling of agricultural tractors by symbolic and numerical multibody codes, the investigation of commercial solutions in terms of comfort, ride and energetic requirements and finally the development of control algorithms for hydro-pneumatic semi- active suspension systems. The main results are validated through experimental activities done by a suspension bench test purposely designed. The experimental sessions consist in the identification of the frequency response of the suspension system and the computation of performance indexes.