Study of hydraulic steering process for articulated heavy vehicles based on the principle of the least resistance

This paper presents a new model for the hydraulic steering mode of articulated heavy vehicles (AHVs). The objective is to obtain the more accurate vehicle performance during steering process. The dynamic analyses of the hydraulic steering system, and the kinematic analyses of steering mechanical structure, including the steering wheel, articulation joint, and struts provide the constraints for the study of steering process with the principle of the least resistance. Meanwhile, a three-DOF dynamic model is developed to analyze the force characteristics of vehicle components. In order to verify the model, field tests and the comparisons with existing research works are performed. The results show that the present model is more effective and similar with the real steering process of AHVs. Moreover, another three conclusions can also be drawn: 1) Only 20% of the hydraulic pressure provides steering driving force. The rest is wasted, which is used to overcome the resistance of outlet pressure in hydraulic system itself. 2) The lateral resistance of each wheel is much greater than the longitudinal, but for the energy consumptions of lateral direction only accounting for 0.1% of longitudinal. Therefore, the lateral forces cannot be ignored in the dynamic model. But for the control strategy with minimum energy consumption, it is useless to consider the energy of lateral impact. 3) Road conditions or vehicle parameters such as the load, the wheel tread, or the wheel base, influence wheel resistances easily, which further influence the vehicle steering process. Furthermore, the vehicle trajectory and differential forces of each wheel obtained from the model are credible to be the reference of intelligent control for AHVs.