Performance of a Fail-Safe Active Suspension with Limited State Feedback for Improved Ride Quality and Reduced Pavement Loading in Heavy Vehicles

The increased number of heavy trucks on today's highways, along with the extended driving hours, resulted in increased demand for improved driving conditions and prompted concern about the dynamic pavement loads. The dynamic pavement loads are one of the major causes of pavement deterioration. Passive suspensions, while being very reliable and easily implementable, fall short of satisfying the various conflicting design requirements. The overwhelming improvement of ride quality resulting from the use of active suspensions seems to have overshadowed their effect on tire generated pavement damage. An in-plane tractor-semitrailer model is used to evaluate the relative performance of fail-safe active and passive suspensions. Both full state feedback and limited state feedback are used in the design of the active suspension. Even when hard to measure road profile signals are eliminated from the feedback scheme, the performance of the active suspension is negligibly affected and remains superior to passive suspension performance. The design of an active suspension is partially governed by subjective choice of the scaling factors in the performance index. The desired vehicle performance can be achieved by tuning these scaling factors and consequently evaluating the suspension feedback gains.