Generalized Template for Suspension Dynamic Modeling With the Use of Bond Graphs

Alex Beckerman and Francis Assadian

This paper develops a practical template for modeling various automotive suspension configurations based on known suspension kinematic equations or lookup tables. This is done with bond graphs, a physical modeling technique. The development of suspension models using this template has many practical applications in the study of steering feel, vehicle handling, and ride comfort through the study of such model outputs as rack force, tire normal force, and sprung mass vertical acceleration.

To illustrate the process, the template is applied to a single degree-of-freedom MacPherson strut suspension whose kinematic equations and lookup tables are available. The sprung mass is constrained to move vertically while the unsprung mass is free to move in three translational and three rotational directions. Each direction has an associated inertia.  This enhanced geometry allows for the calculation of toe, camber, caster, nonlinear strut length, among others. Inputs to the model include prescribed rack motion, unsprung mass vertical motion, and tire forces and moments defined in a Pacejka tire model frame.

Comments are closed.