Cab Suspension Optimization Using Matlab

Driver's ride comfort is an important characteristic in heavy commercial vehicle cab design. Optimizing the ride behavior for different cab variants and vehicle applications is a challenge for cab design and development engineers. Suspension parameter tuning with physical test is time consuming and costly. Therefore, a lumped parameter quarter car model of suspended cab is developed in MATLAB® tool SimScape which includes cab mass, springs and dampers for predicting ride behavior as per ISO 2631. The study is done for a 25 t rigid truck. The input to the system is displacement at axles and the output is acceleration measured at cab and chassis level. This output is correlated with test data obtained from physical measurements using Power Spectral Density (PSD) curves, bode plots and level cross count. This proved that simple lumped parameter models which use very few input parameters can be effectively employed in analysis of cab ride in initial design phases. Further, the cab suspension is optimized to improve the ride comfort, with cab suspension stiffness and damping as tunable parameters. This study gives the choice to cab designer to choose the best combination of spring and damper for better ride at initial design phase itself. The number of physical tests required for subjective assessment and validation can be reduced, saving time and cost. In future, this model can be extended for different truck configurations.