A Suspension Model of an Offroad Vehicle using an Automated Procedure based upon Kane´s Equation

Multibody Dynamics Programs that automatically generate the equations of motion enable designers to study the large displacement two/three-dimensional motion of constrained mechanical systems. Most existing multibody programs have been developed to deal with problems in machine and robotic dynamics. While these programs can be applied to vehicle dynamics their use of cartesian coordinates and Lagrangian multipliers make them rather inefficient in vehicle applications. This paper describes the development of a program that automatically generates and solves the equations of motion for two dimensional systems with prescribed displacements and closed loop constraints. The program uses Kane´s method to develop the equations for the system´s generalized coordinates. A simple coordinate partitioning technique is applied to the Jacobian of the loop closure equations to select the dependant coordinates. The elimination of forces of constraint and the use of minimal coordinates makes this approach particularly attractive for vehicle simulations. Results from a simulation of a vehicle are presented.