Preview Control of Pneumatic Rear Suspension Using a Disturbance Observer

Abstract

The main purpose of this work was to investigate the effectiveness of active suspension systems in the case that only rear suspension is controlled via a preview control method utilizing the future road surface roughness. The basic concept used here is as follows: The rear wheels of a vehicle will travel on the same road surface as that on which the front wheels have travelled. If the characteristics of the road surface on which the front wheels have travelled can be estimated, then these estimation results can be applied to control of the rear suspension. For design of an estimator which can estimate the characteristics of the road surface on which the front wheels have travelled, the concept of a disturbance observer is used. This approach has the advantage that the estimator can be designed based on a quarter-car model. Since the road surface roughness equivalent to Coulomb's frictional force is included in the estimation results, the influence of that frictional force on the control performance can be reduced. Also, it is easy to construct the feedback controller of the front suspension in order to improve the robustness for the error between the real road surface and the estimated one. From some experimental results, it was confirmed that the translational motion and the pitching motion can be suppressed with this preview control method.