Controlling an active suspension using methods of optimal control

This paper deals with a control strategy for the vertical dynamics of a passenger quarter-car equipped with an active suspension system. The control objectives are formulated in optimal control problems with different complexity, regarding inequality constraints and nonlinear cost functions. The influence of the different formulations of the optimal control problem on the controlled system is discussed regarding the resulting optimal trajectories in comparison to the passive system. For the favored cost functions the offline calculated solutions for the discretized state-space are then used to generate a state-feedback control. An optimization of calculation time is seeked applying dynamic programming and modal synthesis. The developed controllers are implemented and their performance is analyzed in simulation and at a quarter-car test rig equipped with a hybrid suspension system.