Effect of Chassis Design Factors (CDF) on the Ride Quality Using a Seven Degree of Freedom Vehicle Model

The kinematics and kinetics of a seven degree of freedom vehicle ride model with independent front and rear suspension are developed. Lagrange's equation is used to obtain the mathematical model of the vehicle. The equations of motion are transformed to state space equations in Linear Time Invariant (LTI) form. The effect of Chassis Design Factors (CDF) such as stabilizer bars, stiffness', Dynamic Index in Pitch (DIP) and mass ratio on the vehicle ride quality are investigated. The ride quality of the 3 dimensional vehicle that includes bounce, pitch, roll and unsprung masses motion is demonstrated in time domain response. The vehicle is considered as a Multi-Input-Multi-Output System (MIMO) subjected to deterministic ground inputs. Outputs of interest for the ride quality investigation are vertical and angular displacement and vertical accelerations. Numerical computer simulation analysis is performed using MATLAB® software. The uniqueness of this research is the implementation of classical mechanics and modern dynamic systems using state-space approach to investigate ride quality. The simulation and analysis are performed using vehicle parameter data of an SUV. The research shows that choosing the appropriate design factors are critical for optimal ride quality.