Reduced Order Design of Active Suspension Control

The presence of fast and slow modes in suspension systems is utilized in the design of two reduced-order active suspension control strategies. The first strategy is obtained by combining the solutions of slow and fast control sub-problems. The second strategy is based on a two-level hierarchical control design. The local level requires measurements of local fast variables, namely the unsprung mass velocities. The coordinating level relies on measurements of slow variables, namely, suspension deflections, sprung mass velocity, and mass pitch rate. Neither strategy requires tire deflection measurements. In spite of their simplified structure, simulation results indicate that their performance is comparable to that of the full-state feedback design.