Stability Analysis And Evaluation Of The Tractor-semitrailer Manipulation

With the rapid development of Chinese high-grade highway network, the tractor-semitrailer plays an increasingly important role in material circulation with its hang volume, low cost advantages and high efficiency. Compared with the ordinary vehicle, the force of tractor-semitrailer is more complex, because of structure of combination and interacting between tractor and trailer. As loadage and running speed of tractor-semitrailer increased with technology advances, it is prone to "jackknifing","sway","oscillatory" and induces handling instability, so it is necessary to analyze the handling stability of tractor-semitrailer.Considers the lateral and yaw motions of tractor and trailer respectively, four degrees of freedom model is established with linear and nonlinear tire model, where the nonlinear tire model using the simplified magic formula tire model. Based on linear vehicle model, combined with the tractor and trailer understeer gradient, the tractor-semitrailer handling stability and lateral stability were studied. Tractor-semitrailer understeer gradient and articulation angle gain were investigated with the changing of structural parameters, the articulation angle gain was used to analyze the stability of tractor trailer at different use and structural parameters. Using the stability theory of dynamic system, through the analysis of the tractor trailer understeer gradient, articulation angle gain and damping ratio of the system change, the relationship was discussed between lateral instabilities and handling properties, a common method is established to evaluate the handling and stability. Based on the nonlinear vehicle model, the handling diagram was used to analyze the stability of tractor trailer at different use and structural parameters, and compared it with the linear vehicle model; the A and Y handling surface was used to describe the steady-state properties of a tractor-semitrailer at different maneuver; depending on H handling surface and tractor-semitrailer understeer gradient which can deduced from the contour line of the H surface, the stability of a tractor-semitrailer are analyzed at particular maneuver. With the nonlinear dynamics theory, the relationship of equilibrium with load scenarios is analyzed, discusses the tractor-semitrailer lateral instability and mechanisms at critical situations.