# Analysis of Longitudinal Braking Stability of Lightweight Liquid Storage Mini-Track Vehicles
## 5 Conclusions  
The tracked vehicle works at a complex and narrow disaster site, and thus it is important and innovative to investigate its braking stability, which was evaluated in this study. Further, the fluid-structure coupling analysis of oil, liquid tank, and track vehicle was carried out when analyzing the longitudinal stability of tracked vehicle. * The braking dynamics model of the lightweight mini-track vehicle was established. According to the model, the effective braking speed reduction was positively correlated with the total mass of the tracked vehicle when the tracked vehicle was impacted by the liquid tank during running. Furthermore, it was negatively correlated with the longitudinal impact force of the liquid oscillation. In other words, the smaller the tracked vehicle mass, the greater the longitudinal impact force. Moreover, smaller vehicle mass also corresponds to a smaller effective braking deceleration, inferior longitudinal stability, and longer braking time. * Based on the fluid motion equation applied to the liquid tank and the theoretical model of longitudinal impact force, the influences of the TLR, IV, and IBD on the longitudinal stability of the observed vehicle were analyzed. It is noteworthy that the control variable method and the fluid simulation software FLUENT 2023 were used. The results show that the TLR significantly impacted the braking efficiency of the tracked vehicle. The braking effect was the weakest for the filling ratio of 0.7, and the braking efficiency decreased by 32% compared to its initial value. Changing only the IV exhibited a limited effect on the longitudinal stability of the tracked vehicle. Further, the braking efficiency was also reduced by about 30% compared with the IBD. When the IBD was changed, the braking efficiency reduction rate was positively correlated with it. Finally, when the IBD speed was increased to 5 m\(\cdot\)s\({}^{-2}\), the braking efficiency decreased by more than 48%. Figure 19: Experimental data obtained for longitudinal angular displacement of the tracked vehicle during starting, accelerating, walking, and braking: (**a**) IV 1 km\(\cdot\)h\({}^{-1}\); (**b**) IV 2 km\(\cdot\)h\({}^{-1}\); (**c**) IV 3 km\(\cdot\)h\({}^{-1}\); and (**d**) comparison of each IV condition. * The dynamic stability experimental platform of the lightweight mini-tracked vehicle was built. The limit conditions of the TLR of 0.7 and effective braking deceleration of 4 m\(\cdot\)s\({}^{-2}\) were selected for the experimental case. The longitudinal stability of the tracked vehicle during the starting, accelerating, walking, and emergency braking at IVs of 1, 2, and 3 km\(\cdot\)h\({}^{-1}\) was evaluated. Based on the results, the following conclusions were drawn: when the TLR and effective braking deceleration were constant, the change in the IV exhibited a limited effect on the effective braking deceleration. Compared to the simulation results, the AEBD obtained in the experiment was smaller. This was due to the sudden acceleration or braking of the tracked vehicle during the road experiment, which caused forced vibration of its motor, gearbox, and pump, among other components. The forced vibration led to a further increase in the longitudinal force of the liquid, thus reducing effective braking deceleration. * When the tracked vehicle accelerated and braked under extreme conditions, the front and rear tilt angles were approximately 4\({}^{\circ}\). This value is below 5\({}^{\circ}\), which indicates that the stability requirements are met. * Owing to time and resource constraints, only the longitudinal stability of the tracked vehicle during the braking was studied. However, the road conditions of the tracked vehicle during the rescue were harsh. Therefore, it might be valuable to systematically examine the lateral rollover stability and longitudinal stability of the tracked vehicle under various working conditions. Conceptualization, C.Z. ; methodology, X.C. ; software, L.X. ; project administration, X.C. ; results analysis and discussion, C.Z. and X.C.