Dynamic Analysis And Control Study Of The Trailer

Compared to other vehicles, the advantage of the trailer gives its prominence for transporting lots of goods and carrying heavy goods. This is conducive to the point to point transportation, left hanging transportation and ro-ro transportation. It can realize the connection between the highway transportation and waterway transportation. Flexibility of the trailer is enough strong. It can meet the requirements of large and medium-sized enterprises in transportation. The trailer brings business value for the enterprise, but at the same time, it also causes traffic accidents. It is a composite structure. The movement of tractor and carriage is both independent and mutual coupling. Its movement is much more complex than the traditional passenger car. With the development of technology, the loading capacity and driving speed of the trailer has significantly improved. Its disadvantage is that it is liable to occur “fold”, ”spin” and “horizontal shimmy” unstable phenomenon during normal driving. Therefore it is necessary to analyze and the design of control for the steering stability of the trailer.The main content of this thesis is arranged as follows:Firstly, this paper considers the lateral movement and yaw movement of the tractor and carriage. So we establish two-degree-of-freedom linear vehicle model and nonlinear vehicle model. Among them, the cubic nonlinear tire model is used in the tire model of the nonlinear vehicle model. It simplifies the complexity of tire model.Secondly, the dynamics model was presented based on the dynamics analysis, as the tractor sideslip angle, the yaw rate of tractor and carriage and relative yaw angle as the states. Aimed at uncertainty of parameters of the trailer, the sliding mode control system and fractional sliding mode control system is designed based on the front wheel steering of the carriage. A simulation experiment has been carried on in the MATLAB/Simulink environment and the superiority of these two kinds of control algorithm. The result shows the fractional sliding mode control strategy have stronger robustness than the integral compensation method. So they could control the relative yaw angle between the tractor and carriages in a larger stable range and prevent them from fold effectively. It also could better able to track the desired yaw rate of the vehicle and improve the lateral stability of the trailer.Finally, the nonlinear instability forms model of the trailer is mainly studied. The vehicle model of the trailer is fitted with the magic tire model, thus obtained to the cubic nonlinear tire formula. Then the complete nonlinear dynamic model of the vehicle is established. According to the Routh Criterion, the robust stability of the equilibrium point of the necessary and sufficient conditions is analyzed. As a result, the transverse shimmy of the different speed condition is analyzed and compared through data by MATALB simulation. Thus understanding the instability in the form of the vehicle was understood. At the same time, the nonlinear vehicle model, the introduction of fractional order sliding mode control, the yawing angular velocity and the relative changes of the yawing angle is closer to actual working condition, has the very good reference value.