An Analysis of Ride Coupling in Automobile Suspensions

Abstract The tuning of a pitch-plane model of a passenger car with a ‘coupled’ suspension system was investigated and compared to that of a conventional suspension system. Direct comparison of stiffness matrices for the two models was used as well as modal analysis and frequency domain analysis, to gain insight into the optimal pitch-bounce tuning. Performance was measured in terms of body acceleration, dynamic tyre force, and suspension working space. Optimum tuning of the coupled system was found to be at lower pitch stiffness, but greater pitch damping than that of a popular saloon car. Uncorrelated inputs to the model were found to give tuning suitable for a realistic range of road speeds from 5 to 25 m/s. The Olley suspension tuning criterion was found to represent an optimal conventional suspension stiffness tuning for dynamic tyre force minimization, but not for driver chest acceleration minimization.