In this paper, a longitudinal-vertical coupling dynamic model of a tracked vehicle under uneven road conditions is established. The torsion suspension forces and torques generated by the torsion bar springs and torsion shock absorbers are considered in the present model. The tracked vehicle’s longitudinal acceleration and velocity change at the same time as the vehicle heaves under the excitation of uneven road terrain. The vehicle’s longitudinal-vertical coupling dynamics are explained elementarily by analysing the longitudinal and vertical dynamics of a road wheel based on the road wheel force model. From the coupling tracked vehicle model, the dynamic responses of the vehicle in the vertical and pitch directions as well as the longitudinal direction are investigated. The vehicle dynamics characteristics are compared with those obtained by Recurdyn simulation. The results indicate that the proposed dynamic model performs well in predicting the dynamic characteristics of the tracked vehicle on uneven roads. By means of the coupling dynamic model, the influences of vehicle speed and road conditions on the vehicle’s longitudinal dynamics are further studied. It has been found that both a higher velocity and a larger roughness coefficient will lead to a negative longitudinal acceleration with larger absolute value.

In this paper, a longitudinal-vertical coupling tracked vehicle dynamic model is established to simultaneously describe the longitudinal, vertical and pitch dynamic responses of the tracked vehicle under off-road conditions. The road wheels are subjected to variable longitudinal-vertical forces due to the terrain unevenness and the excitations are transmitted to the vehicle body through the torsion suspension system. An experiment by means of a scaled-down tracked vehicle was carried out. The comparisons between the field test results and simulation results verified the effectiveness of the coupling dynamic model on predicting the vehicle dynamics. Taking advantage of the coupling tracked vehicle dynamic model, the energy computation formulas are further derived to quantitatively study the vehicle energy consumptions. The energy consumption distributions of the tracked vehicle on uneven road and paved road at different velocities are analysed. The computation results indicate that the developed energy computation method is reliable on predicting the energy generation and dissipation of the tracked vehicle. It has been found that the proportions of damping dissipation energy and road roughness caused energy consumption to total energy consumption are both higher at a greater speed.