Study On Steering Mode And Stability To Large All Terrain Crane

All terrain crane has the advantages of high speed and high climbing ability.And it can work in the field and other conditions of poor working conditions. So the application of all terrain crane is very extensive. But for large tonnage of all terrain crane, There exist many problems due to shaft multiple, such as low-speed maneuverability, high-speed stability and so on. Therefore, it is very important to study the steering stability of multi-axle vehicle, which has theoretical and practical significance to improve the steering stability.Firstly, this paper introduces several commonly used vehicle steering system and expounds the multi-axis(axis number is greater than or equal to 5)of all terrain crane steering model and vehicle stability evaluation index, laying the groundwork for the analysis of the theory and research.Secondly, the dynamic differential equation of 3-DOF is established by using the Lagrange equation. This paper use roll speed, roll angle, sideslip angle,yaw rate and other parameters as the research object. Simulation and comparative analysis of four kinds of steering modes are done by MATLAB software.Finally, all terrain crane’s steering stability is studied from two aspects: the internal vehicle design parameters and the external control strategy. This paper puts forward the improvement measures to the problem.For the influence of design parameters, this paper selects the tire cornering stiffness, suspension roll stiffness and damping coefficients to make theoretical analysis and computer simulation from 2-DOF and 3-DOF. And the quantitative analysis of some simulation curves are also done. The preliminary results of the steering stability’s influence are obtained.For the influence of control strategy, this paper focuses on three kinds of control strategy to make simulation analysis, that is the rear wheel angle which are proportional to the front wheel steering angle and yaw rate, the combined control of proportional control and yaw moment. The use of each controlstrategy and the three strategies are compared and analyzed. At the same time,the fuzzy control strategy with zero side slip angle is analyzed from the angle of three degrees of freedom based on the proposed improvement to preliminary method of stability of multi axle vehicle.