"The suspension system represents a vehicle system at each wheel. It consists of a spring ks, a damper bs and a hydraulic actuator Fa. The tire stiffness and damping properties are also shown by kt and bt, respectively. The effective vehicle body mass is shown by Ms (sprung mass), and Mu (unsprung mass) represents the effective mass for the wheel and axle. The vertical displacements from the static equilibrium for Mu and Ms are shown by xu and xs, respectively. The road profile is represented by xr. The suspension travel xs - xu is measured and compared to the set point (r = 0). The required actuator force is determined by the controller to eliminate the error, and thus, to reduce the vehicle oscillations. The actuator can provide a maximum force of 3000."
Duc Chung Tran (2020). Quarter Car Modelling.zip (https://www.mathworks.com/matlabcentral/fileexchange/46316-quarter-car-modelling-zip), MATLAB Central File Exchange. Retrieved .