| There is a demand for the transportation of overlength,overwidth and overweight goods in the fields of electricity,chemical engineering,and machinery.The existing transportation methods are generally tractor trailer and multi-axle heavy-duty single body vehicles,which have low steering flexibility and poor obstacle avoidance ability.When carrying out-of-gauge goods through large curvature curves,there are difficulties or even inability to pass through.Therefore,more flexible and efficient transportation methods are urgently needed for the transportation of out-of-gauge goods.In response to the above issues,this article proposes the dual automatic guided vehicle intermodal transportation system for out-of-gauge goods.Compared to traditional out-of-gauge goods transportation methods,the dual vehicle intermodal transportation system has unique transportation advantages of high flexibility and strong obstacle avoidance ability,which can effectively improve the passing capacity of out-ofgauge goods in high curvature curves.In addition,this article completes the overall dynamic analysis of the dual vehicle intermodal transportation system using the dual layer two degree of freedom dynamic modeling idea,analyzes the overall motion characteristics of the dual vehicle intermodal transportation system from a dynamic perspective,achieves hierarchical tracking of the turning path of the dual vehicle intermodal transportation system,and provides a dynamic solution method for the dual vehicle intermodal transportation system.The main research content and results of the full text are as follows:1)Design and analysis of turning capacity of the dual vehicle intermodal transportation system.Firstly,clarify the structural form of the dual vehicle intermodal transportation system,select the out-of-gauge goods to be transported,and select appropriate transport vehicles;Secondly,referring to highway standards and real curve data,determine the high curvature turning conditions to be studied in this article;Then,qualitative analysis is conducted on the turning ability of the dual vehicle intermodal transportation system,including the impact of flexible wheelbase on the turning ability of the dual vehicle intermodal transportation system,comparison of turning ability of different transportation methods,and analysis of obstacle avoidance ability of the dual vehicle intermodal transportation system.The above analysis indicates that the dual vehicle intermodal transportation system has unique transportation advantages such as high flexibility and strong obstacle avoidance ability compared to traditional out-of-gauge goods transportation methods.2)Modeling of equivalent monorail vehicle for the dual vehicle intermodal transportation systems.Firstly,the concept of equivalent tire for a single vehicle is proposed,which defines the lateral force exerted by out-of-gauge goods on the guide vehicle-the slope of the guide vehicle sideslip angle curve at 0° as the cornering stiffness of the equivalent wheel.The equivalent wheel cornering stiffness under design conditions is solved through front wheel step input tests;Then,the concept of equivalent monorail vehicle for the dual vehicle intermodal transportation system is proposed,and the dynamic parameters of the equivalent monorail vehicle for the dual vehicle intermodal transportation system are determined based on the parameters of the object being transported and the front and rear vehicles.A two degree of freedom equivalent monorail model of the dual vehicle intermodal transportation system is established.Through the concept of equivalent tire for a single vehicle and equivalent monorail vehicle for the dual vehicle intermodal transportation system,the overall dynamic analysis of the dual vehicle intermodal transportation system is completed using the dynamic modeling concept of double layers and two degrees of freedom.The overall motion characteristics of the dual vehicle intermodal transportation system are analyzed from a dynamic perspective.3)Hierarchical tracking control for the turning path of the dual vehicle intermodal transportation system.First of all,the turning paths of the dual vehicle intermodal transportation system based on the third-order Bezier curve and the arc-line are obtained respectively,and the former is selected as the final curve passing path of the dual vehicle intermodal transportation system through comparison;Secondly,design lateral path tracking controllers for front wheel steering and four-wheel steering vehicles based on LQR;Then,the equivalent monorail vehicle and 4WS-LQR controller are used to track the centroid turning path of the dual vehicle intermodal transportation system,and the turning path of the front and rear vehicles is obtained by combining the actual attitude and geometric constraints of the dual vehicle intermodal transportation system;Finally,the front and rear vehicles and the FWS-LQR controller are used to track the turning paths of the front and rear vehicles decomposed from the upper layer,completing the task of transporting out-of-gauge goods through large curvature curves in the dual vehicle intermodal transportation system. |
