Online force estimation for an active suspension control

While the damping of a common cabin of a commercial vehicle is realized with hydraulic based dampers integrated into the air springs of the suspension, the damping forces of the realized active cabin suspension are generated by varying the mass of air inside the air spring volume. To achieve a high bandwidth of vibration suppression, the mass flow of compressed air is controlled using fast switching valves. To design the force controller, the air spring force has to be known for the feedback. Due to the limited design space and to reduce costs, an observer based concept is chosen, utilizing the already available sensor signals for displacement and acceleration. To ensure an accurate and high dynamic force estimation, two nonlinear state estimator concepts are introduced, which are both capable of considering noisy signals as well. The comparison between estimation results and measured signals shows a good correlation. By use of a superimposed vibration control, the cabin accelerations can be reduced by applying optimal damping forces, which is proven by measurements.