SEMI-ACTIVE SUSPENSION SYSTEMS FOR HEAVY-DUTY VEHICLES: MULTIBODY MODEL DEVELOPMENT, IDENTIFICATION AND CONTROL ALGORITHM EVALUATION

The design of suspension systems for heavy-duty vehicles covers a specific field of automotive industry. During the past few years there has been an increasing demand in power capabilities, loads and driving speeds of heavy duty vehicles. Therefore, off-highway vehicle manufacturers have shown their interest in employing new technologies. This work focuses on the investigation of hydro-pneumatic suspension systems for heavy duty vehicles, in particular on the benefits of a semi-active solution compared to a passive one. The main targets of this activity is the study of the dynamical behaviour of agricultural tractors and the design of a cost-effective controllable suspension, capable to adapt the tractor dynamical behaviour, under different road and load conditions. The work started with the development of a multibody model of the suspension test bench to be used for control solution comparisons. The multibody model was experimentally validated by characterizing the cylinder friction, tire parameters and Frequency Response (F.R.) of the suspension bench test equipped with a passive solution. As a last step the evaluation of different control algorithms for hydraulic semi-active suspension was carried out via Adams/Matlab co-simulation technique