Simulation And Experimental Study On Steering Performance Of All Terrain Crane

This thesis is writing based on school-enterprise cooperation projects which are reliability of driving and design parameters software development of all terrain crane(A,B), the Project Number is 200822010100145 and 2009220101001350, and the Jiangsu Province special fund for science and technology achievements which is the research and industrialization on Large mobile crane, the Project Number is BA2007038. With the vigorous development of energy, transport and other major projects in China as to the global, the market demand for all terrain crane is rapid growth. Multi-axis steering system as the main components of large special vehicles, construction machinery and other major technologies and equipment, which has important strategic significance in enhancing ability of independent innovation of major technical equipment and enhancing Country's economic strength. At present, the building of theory platform of large multi-axis vehicle is just starting, steering technology is turning from mechanical hydraulic power steering to the direction of combining hydraulic power steering and Electronically controlled. The control of Security steering mode is still groping. As to the studying on vehicle handling and stability has no precedent, it lead to the development lags behind of Overall industry in Large multi-axis vehicle in China, therefore, the researching on multi-axis steering of technology, vehicle safety, reliable steering is particularly important.This paper is researching in-depth on Dynamic model manipulation of Multi-axis Steering Vehicle, virtual prototype simulation of complex systems and experimental rsearch,secondary development, steering control algorithm for multi-axis and so on.Mathematical model is a key core technology of engineering practice and the basis of multi-axis steering of research. This paper established Linear model of two degrees of freedom and Linear model of three degrees of freedom of multi-axis steering vehicle, derived the transfer function from front corner to yaw rate, sideslip angle and vehicle body side angle under the conditions of meeting Ackerman's law and the steady-state gain expressions during thenm, got the Vehicle stability factor expression and the factors which affect vehicle steering stability. Analysised the relationship of the projection distance to the vehicle body of centroid and the steering center of the vehicle under the conditions of the other side of the angle control strategy. Respectively analyzed in low-speed, high-speed conditions, the Vehicle steering performance.the impact on vehicle steering performance under the model of front wheel steering vehicle, all-wheel steering vehicle and electronic control steering the vehicle steering performance.Based on the dynamic manipulation model of Linear three degrees of freedom,builded the model of nonlinear three degrees of freedom,cosidered importantly tire nonlinear cornering stiffness impact on vehicle steering performance and conducted a case study.The moment of friction between tire and the ground is two to three when steering in situ than driving steering. Tire cornering performance in situ is important to steering system matching. Taking into account that the empirical formula of steering resistance in situ couldn't describe the relation between steering resistance torque and tire rotations, we conducted real vehicle tests for steering resistance in situ, and also introduced the "magic formula" and Lugre model into the analysis of steering resistance in situ, and got good agreement. Testing and analysis indicate that they have nonlinear relationship between steering resistance torque and tire rotations, the resistance increased with the increase of the wheel rotation, and in finally tended to a constant value.Considering the problem that the steering rods and steering tie rod appeared breaking when all terrain crane is in use,we conducted a spot steering real vehicle testing and virtual prototype simulation for some seven-axis vehicle,the simulation results are consisitence with the experimental results,and also we got the trend of bar force. In it does not change the linkage of parameters steering and ensure that wheels meet the Ackerman Law context, We optimized design steering cylinder size and location parameters, significantly reduced the stress state of steering Linkage and steering tie rod, Increased the reliability of steering Linkage and steering tie rod. Morever, this design has been used by businesses and successfully applied to other product design. Hydraulic steering system is an important part of all terrain crane. According the actual structure of constant current valves, emergency valves and diverter, it builded each virtual prototype simulation model, analyzed their performance, and also conducted bench testing and validation. Based on these, it builded the virtual prototype simulation model of steering-hydraulic integration, and also conducted vehicle testing when the vehicle steering in situ, passed the verification of test results, Identified the correctness of multi-axis turning vehicle virtual prototype model.Because it needed the pressure of the hydraulic system required which was different when the vehicle Pivot steered and drive steered, it could appear the problem of sharp increasing in hydraulic system pressure and mutating of bars force when the wheels turn to the "limit"position, we researched and improved the hydraulic steering system.According the characteristics of all terrain crane, by the software of AMESIM, we developed the hydraulic components library of hydraulic steering system, used ADAMS, we developed parametric Model of mechanical system and optimizer, based on these, we used Visual Basic to develop the platform of the simulation and analysis of steering system for multi-axis steering vehicle. It greatly improved the efficiency and accuracy of design, improved reliability. Now, this paltform has been used by business sucessfully, and also successfully applied to the development and analysis of the appropriate product.At present, the research on handling and stability of large multi-axis steering vehicles just start at home, there is no experimental research on the whole vehicle. In this thesis, it conducted firstly the whole vehicle test of handling and stability of all terrain crane, selected a six-axle vehicles, and then conducted the snake test and steady-state circular test for the whole vehicle. The next, it simulated and analysed the virtual prototyping, further verified the validity of the model. It provided a reference for handling and stability of multi-axis vehicle.In order to reduce tire wear of multi-axis, we improved the handling model of multi-axis steering vehicle, by controling the corner of the wheel axles of any two to control the corner of the other wheel axle, combining the model of multi-axis steering vehicle with the handling model of two-axle vehicle. So some of steering control algorithm of two-axle vehicle could be used in multi-axis vehicle, improved the versatility of some of the control algorithm.By introducing the method of yaw moment control to the mechanical steering vehicle, to improve the steering performance of mechanical steering vehicle included.Using the zero steady-state error tracking control theory, we designed tracking controller of three degrees of freedom multi-axis turning vehicles, analyzed and compared that this controller was impact on the steering performance of all terrain crane. Simulation results show that all terrain crane which used the tracking controller had good tracking performance, could improve the steering performance of vehicle according to actual needs, and guarante the safety and handling stability of all terrain crane.In this paper, it used the research methods of thecombination of virtual simulation and real vehicle testing, depth research on the performance of hydraulic steering system and complex mechanical system in steering. Achieved theoretical analysis and experimental validation with each other and promote each other, orovided theoretical support for the designing of multi-axissteering vehicle, provided some reference for the research of the handling and stability of multi-axis steering vehicle.