Design, Modeling, and Analysis of Heave and Roll Decoupled Suspension Geometry for a Formula Student Prototype

This work aims to present the application of mode coupling to a Formula Student racing vehicle and propose a solution. The major modes of a vehicle are heave, pitch, roll, and warp. All these modes are highly coupled – which means changing suspension rates or geometry will affect all of them – while alleviating some and making others worse characteristics. Decoupling these modes, or at least some of them, would provide more control over suspension setup and more refined race car dynamics for a given layout of the racetrack. This could improve mechanical grip and yield significant performance improvements in closed-circuit racing. If exploited well, this approach could also assist in the operation of the vehicle at an optimal kinematic state of the suspension systems, to gain the best wheel orientations and maximize grip from the tires under the high lateral accelerations and varied excitations seen on a typical road course. Previous strategies used by other researchers to achieve similar goals are reviewed as part of this work. Some common topologies to achieve the same results are summarized, and conventional suspensions without decoupling are compared and contrasted. Ultimately, this work focuses on the heave and roll decoupling mechanisms for conventional passive suspensions, rather than full active mode decoupling, to recognize the practical constraints of time and cost that are faced by Formula Student teams.