| Currently, tractor-semitrailer plays a dominant role in road freight transportation due to its cargo-carrying capacity and transportation cost. However, a number of reasons lead to the bad performance and even accident situation of tractor-semitrailers in China. First, because of the increasing vehicle speed and traffic volume, the probability of tractor-semitrailer steering under high speed situation becomes higher. Second, due to the independent production and management mode, the matching of tractor-semitrailers is often ignored, so it is difficult to ensure vehicles’ integrated security. Therefore, the tractor-semitrailers’ dynamic characteristics in high speed and different steering conditions should be explored to improve their maneuverability and stability.The tractor-semitrailer’ dynamic characteristics will change a lot when it drives in extreme conditions. Therefore, this paper aims to explore the dynamic characteristic of plane motion, energy conversion, master the essence of stability mechanism and nonlinear dynamic characteristics of tractor-semitrailer, and provide theoretical basis for safer driving. The specific contents are as follows:(1) Based on system dynamics theory, the dynamic multi-degree-of-freedom model of tractor-semitrailers derived; then, vehicle dynamics model is transformed into the state space expression by using matrix conversion according to the selected state variables. By applying Matlab/Simulink to build the tractor-semitrailer model, the dynamic characteristics are simulated under the empty load or full load condition at a certain speed, and the characteristics are analyzed based on the built model.(2) To verify and improve the accuracy of the proposed model, Magic Formula is adopted to establish the dynamic three-degree-of-freedom model of tractor-semitrailer. By using Matlab/Simulink to build vehicle model, the dynamic characteristics are simulated under different loads and steering conditions. The simulation results are then compared with those of linear model to provide reliable data support for subsequent energy analysis.(3) Based on the compiled program and the non-linear model’s simulation results, the steering stability of the tractor-semitrailer is analyzed from the perspective of energy conversion. It is then compared with the dynamic characteristics under the same experimental conditions to conduct a preliminary exploration of the relationship between them. |
