Semi-Active Strategies for Racing Car Suspension Control

Quite a lot has been written on active suspension, the topic being suitable for theoretical studies. Unfortunately only a few applications has seen the road and even less went into production; by now very few road cars equipped with a real active suspension system are available on the market, and the interest to this kind of application seems to be reduced, perhaps because of high costs and restrictive regulations applied to the race car world. For this reason this paper presents the results of a study conducted on the vertical dynamics of a two wheel car model with a semi active suspension system, a possible alternative way to a fully active system to considerably improve suspension performance. Here the damping force of each suspension is obtained by modulating its damping factor according to opportune functions of the system state variables. This allows to reach several of the objectives achievable with a fully active suspension, without the need of a big amount of energy.