Simulation Analysis On Braking-performance Of Multi-axle Vehicle

With the development of construction and production needs,a number of high-power,large carrying capacity special large all terrain cranes has been widely used.Due to road conditions,and traffic regulations,to rely solely on a single shaft to increase the carrying capacity and to lower vehicle quality has failed.Only by increasing the number of axles,can we meet the requirements of national standards. Therefore more attentions have to be paid to the safety performance of the use of the multi-axis heavy-duty vehicles.Braking performance is one of the most important functions of vehicles.The importance of vehicle braking performance was increasingly apparent with the increase of the speed and the density of the road traffic. The structural difference between the multi-axle vehicle and the ordinary,make the analysis of the two kinds of vehicles different.And there are so few related literatures about the project.Thus the air braking system,tires and ground,vehicles and their associated self-assembly properties that are related to the braking performance and so on will be studied in-depth.The accurate parameters can be achieved by trial,but there exist a lot of complicated elements in reality.Some parameters and their changing disciplines are constrained by trial conditions,we cannot measure.The disadvantages of the experimental investigations as follows:First,the high workload, the long period and the high cost.It also needs vehicles,ground,manpower,fuel and so on;Second,it will be dangerous to brake,especially high speed braking;Third,it is of blindness to do experimental investigations without any preparation and optimal design of the parameters.With the development of the computing technology,simulation analysis becomes one of the methods to research on vehicle properties.In this paper,heavy vehicles and multi-axis braking performance related to the various parts of the mathematical model are built,and then based on mathematical model and make use of the MATLAB/Simulink software,the model has been built.The simulation analyses of different working conditions as follows:(1) Combine the characteristics of the structure of multi-axle vehicle,multi-axis pneumatic braking system of four lines have be designed for heavy-duty vehicles. According to their basic structural characteristics,in accordance with air pressure drive system dynamics and the basic principles of mechanical equilibrium,the establishment of control of piping,braking air rooms and the mathematical model. The establishment of the entire air braking system simulation model,thereby braking system on the pressure characteristics of the non-linear analysis and discussion by the braking chamber pressure changes in air pressure over time curve,as well as putting the braking torque and putting the relationship between stroke,hoofed clearance on the brake drum pressure chamber.(2) Based on the two-axle vehicle braking model,considering the precision of the model and the feasibility synthetically,making use of the theorem of momentum and moment of momentum theorem in Newton vector Dynamic systems,3 + 2n DOF model in simple working conditions and 6 + 4n DOF model in complicated working conditions for simulation analysis have been built.(3) Through an analysis of the theoretical tire models,come toαhow to influence of the vertical angle and the ratio of the vertical and horizontal power in the joint work condition,and then on this basis,pure data have been processed,joint working condition data has been derived,and then draw aligning torque through the theoretical model in the joint work conditions.(4) For different work conditions,road roughness model has been built respectively on the highway,main road and the slip road to the simulation,the surface displacement with time is obtained.As a result of multi-axis road vehicles are often operating in complex and ever-changing conditions,in order to achieve the establishment of road conditions and more hopping coefficient of friction,separation, staggered and grid four road conditions attached to describing the model for vehicle dynamics simulation analysis of the corresponding input.(5) The access control of the ABS and layout of the vehicle braking performance analysis of the effects of drawing on the experience of the successful application of ABS,combined with the characteristics of the multi-axle vehicle,the axis of a vehicle equipped with ABS the seven options.Through comparative analysis,further arranged in accordance with the basic principles and methods of ABS,Balance between economy,initially set a more reasonable program of ABS.Considered the advantages and disadvantages of Fuzzy Control Method and Self-Optimizing theory,and combined with them,adaptive Fuzzy Control Method has been put forward. Self-Optimizing controller has been built by using of Matlab/Simulink.(6) By using of Matlab/Simulink,the model of braking-performance simulation analysis of the vehicle is obtained.For vehicle braking performance evaluation index, linear braking and cornering braking simulation analysis under different road conditions and the ABS to determine the initial layout of the program were analyzed.