Model development, validation and nonlinear control of pneumatic suspensions

Pneumatic suspensions are widely used at present in the truck industry. The passive controllability of the parameters of these suspensions makes them suitable for load adapted suspensions. However, active control of these systems is challenging because of their parameter uncertainties and their highly nonlinear behavior. The ultimate goal of this research is to develop an active pneumatic suspension system to improve the ride comfort and performance of car suspensions. For this purpose, dimensional analysis was applied to the half car model of the Honda Civic. The conventional suspension of the Honda Civic was replaced by a pneumatic suspension. Its scaled half car model was designed and built. The parameters of the air spring were identified by carrying out a series of static experiments and frequency analysis on the physical air spring/load system. The mathematical model was validated by experimental results. Different nonlinear controllers were applied to the mathematical model of a quarter car Honda Civic equipped with an active pneumatic suspension. The first order sliding mode feedback linearization controller (SMFLC) with parameter estimator offers the best ride comfort and performance. The performance of this controller is further studied on the half car model in the presence of different model uncertainties.