Figure 1: A free-body diagram of the half-car model
Figure 1 illustrates the modeled characteristics of the half-car. The front and rear suspension are modeled as spring/damper systems. A more detailed model would include a tire model, and damper nonlinearities such as velocity-dependent damping (with greater damping during rebound than compression). The vehicle body has pitch and bounce degrees of freedom. They are represented in the model by four states: vertical displacement, vertical velocity, pitch angular displacement, and pitch angular velocity. A full model with six degrees of freedom can be implemented using vector algebra blocks to perform axis transformations and force/displacement/velocity calculations. The front suspension influences the bounce (i.e. vertical degree of freedom) according to Equation 1.