Flatness Based Control of a Suspension System: A GPI Observer Approach

We propose a robust, flatness based, approach for active regulation of a railway vehicle suspension system externally perturbed by track irregularities. A simplified perturbed input--to--flat-output model for the vehicle model, which is differentially flat, is established. The observer-based control scheme uses the simplified model considering all the additive state-dependent terms and the influence of external disturbance inputs, as a single lumped unknown but bounded disturbance signal. The proposed GPI observer simultaneously estimates the required flat output associated phase variables allowing to complete the linear feedback loop via on-line disturbance cancellation. Simulations reveal the effectiveness of the approach.