Chaotic behaviors of a ground vehicle oscillating system with passengers

In this paper, some considerations regarding a ground vehicle oscillating system based on chaotic behaviors are studied. The vehicle system is modeled as a full nonlinear seven-degree freedom with an additional degree of freedom for each passenger. Roughness of the road surface is considered as sinusoidal waveforms with time delays for the tires. The governing differential equations are extracted under Newton-Euler laws and solved via numerical methods. The dynamic behavior of the system is investigated by special nonlinear techniques such as bifurcation diagram, time series, phase plane portrait, power spectrum, Poincarʹe section, and maximum Lyapunov exponents. The time delays between the tires are used as a control parameter. First, the vehicle behavior is investigated and the chaotic regions are detected. Then, the damping and stiffness coefficients are used to return to the regular behavior. Results show that by changing the system parameters and selecting the appropriate values, one can minimize vibrations as well as eliminate chaotic behavior. The comparison of the results obtained from the proposed model and those from the vehicle without passengers show the great differences in the dynamic behaviors of the two models.