Etude et analyse de la suspension active et semi-active des vehicules routiers

The objective of this research is to analyze the influence of vibration on the comfort and the stability of the vehicles for the variation of many parameters like the suspensions coefficients, the vehicle velocity, the road irregularities and the seat position. A mathematical model to simulate the dynamic movement of a vehicle has been developed. This model can use nonlinear suspensions such as active and semi-active suspensions. In the second part of this research, a nonlinear seat model has been developed using experimental data. We have exploited this nonlinear seat to give a better explanation of the interface between the driver and the seat.; With a detailed study of the vibration and its effect on the human body, we have concluded that the natural frequency of the human body (1 to 20 Hz) has the same range of the vibration frequency generated by the road irregularities. A temporal profile based on the power spectral density (PSD) has been generated. To justify our mathematical model, we have simulated a quarter car model with passive, active and semi-active suspension. The force generated by the nonlinear suspension is based on the principles of the full state feedback law (fl) and the velocity feedback law (vl). We have showed that the principle vl can be used on the vehicle domain because the energy consumed by it is less than the fl principle and with the vl principle we have only one parameter to control. To complete this analysis, we have developed an optimization method to control the comfort and the stability parameters of the vehicle. Furthermore, with an analytical derivation, we have found the optimal parameters suspensions.; To validate this approach, 2-D and 3-D vehicle models have been analyzed. Results from these models for a random road excitation, a simple bump and a double bump showed that the active and semi-active suspensions increase the comfort level from 30% to 50% compared to the passive suspension. For example, for the 3-D model the comfort increase was in average 30% for the vertical driver acceleration, 30% for the vertical unsprung mass acceleration and 50% for the roll acceleration. However, the pitch acceleration was in the same level for the three suspensions models because we have controlled the pitch movement by introducing specific constraints.; Finally, with the experimental results obtained on the seat at the CONCAVE center of the University of Concordia we have calibrated the numerical seat model. After a comparison between the experimental and the numerical results, we have concluded that the active and the semi-active suspension increases the comfort on the seat by 20% to 30% compared to the conventional one. With this analysis, we have concluded that is better to apply the active and semi-active suspension to the seat because in many cases, like the construction and the mining area, the vehicle drivers are exposed to high amplitude vibrations.