Nonlinear analysis and control of a variable-geometry suspension system

The paper proposes methods for both the analysis and the synthesis of variable-geometry suspension systems. The nonlinear polynomial Sum-of-Squares (SOS) programming method is applied in the analysis and it gives the optimal utilization of the maximum control forces on the tires. Moreover, the construction of the system can be based on the nonlinear analysis. The variable-geometry suspension system affects the wheel camber angle and generates an additional steering angle, thus the coordination of steering and wheel tilting can be handled. An LPV (Linear Parameter-Varying) based control-oriented modeling and control design for lateral vehicle dynamics are also proposed. The novelty of the method is the combination of the LPV-based control design and the SOS-based invariant set analysis. The simulation example presents the efficiency of the variable-geometry suspension system and it shows that the system is suitable to be used as a driver assistance system. In the SIL (software-in-the-loop) simulation both the dSPACE-AutoBox hardware and the CarSim simulator are used as standard industrial tools.