Research On Lateral Stability Judgment And Control Of Tractor-semitrailer

Tractor-semitrailer has the advantages of economy,efficiency and large volume of transportation,so it plays an important role in the transportation of goods.Nevertheless,because of its high center of mass,long body length,large load capacity and mutual coupling between the tractor and the semi-trailer,it is prone to tail,fold and side slip when driving on a low adhesion coefficient road,and it is prone to cause rollover accidents when driving on a high adhesion coefficient road.In recent years,some heavy traffic accidents have occurred in China’s tractor-semitrailer,causing huge economic and social losses.Hence,the driving stability and safety of tractor-semitra iler have become a major problem restricting the development of China’s road transport industry.This paper studies the lateral stability of rollover and folding of tractor-semitrailer.Based on K means clustering analysis,the method of determining the rollover and folding stability of tractor-semitrailer is proposed.The stability of tractor-semitrailer is controlled by combining differential braking and fuzzy control.The main work is reflected in:1)The five-degree-of-freedom dynamic model of the tractor-semitrailer and the Truck Sim vehicle model are established.The steering simulations of the Truck Sim vehicle model and the five-degree-of-freedom dynamic model are carried out under the steering wheel angle step input and double shift line conditions.2)K means clustering method is used to judge the risk of vehicle rollover and folding and online identification.The main state parameters of the vehicle and cluster analysis results are used to verify the results.Firstly,the simulation conditions and output state parameters are set by Truck Sim software,and the K means clustering analysis method is used to perform offline cluster analysis on the vehicle driving state parameters,and the cluster centroid is obtained and four danger levels are determined.Then,the semi-hanging is used.The hinge angle and hinge angular velocity of the car train are compared and verified.The stability of the rollover is verified by the tilt angle of the semi-trailer.Finally,the online dangerous situation identification is carried out,and the joint simulation platform of Truck Sim and Simulink is established.The realtime state parameters generated by the tractor-semitrailer and the offline cluster centroid are used to calculate the Euclidean distance,and the dangerous state of the tractor-semitrailer is divided and determined.The simulation results show that the method can effectively determine the state change of the rollover and folding stabilit y of the semi-trailer.3)Using the combination of differential braking technology,fuzzy control technology and slip rate control to control vehicle rollover and folding instabilit y.Firstly,the hazard level of the folding and rollover of the tractor-semitrailer is determined online by cluster analysis.Then,it is decided to choose the anti-rollo ver control or the anti-folding control to perform differential braking control on the vehicle to avoid the instability phenomenon.Finally,the simulation experiments of steering wheel angle step input and double shift line operation are carried out.The simula t io n results show that the control strategy designed in this paper can improve the lateral stability of tractor-semitrailer.