Numerical kinematic analysis of the double wishbone motor-vehicle suspension system

In this paper, an efficient numerical algorithm for the kinematic analysis of a double wishbone suspension is presented. The double wishbone suspension system is usually used for front wheel axles of rear wheel driven cars. The kinematic analysis of the one-DOF suspension mechanism is carried out in terms of the rectangular Cartesian coordinates of some defined points in the links and the joints. Geometric constraints that fix the distances between the points belonging to the same rigid link are introduced. Additional driving constraints are added as a function of the input driving variables. The nonlinear constraint equations are solved by iterative numerical methods. The corresponding linear equations of velocity and acceleration are solved numerically to yield the velocities and accelerations of the unknown points on the wheel knuckle. The velocities and accelerations of the other points of interest can be calculated if their positions are locally specified. In addition, the angular velocity and acceleration of any link in the mechanism are evaluated. The presented formulation in terms of the system of coordinates based on the presented formulation in terms of the system of coordinates based on Cartesian coordinates of specified link points is simple and involves only elementary mathematics. A numerical example is presented.