Research On Control Strategy Of Handling Stability For Multi-Wheel Steering System Of All Terrain Crane

All Terrain Crane is a new kind of high-efficient hoist apparatus , its has some advantages of truck crane and rough terrain crane , such main characteristics as moves fast and goes with load on rough terrain. Compared with general truck crane, it has more superior jack-up performance and stronger cross-country ability. In addition, it can meet the needs of different working environment. ,In our country, the development of all terrain crane start relatively late, the research on multi-axle steering system is not deep.In recent years, In our country , also design some all terrain truck cranes, which have two steering axle and even more. Though all the type of all terrain crane have multi-axle steering system, the way of multi-axle steering is extremely simple and the technology is unripe, In addition, the defect exiting in steering system limit moving flexibility of all terrain crane, moreover, the problem aggravated the wearing and tearing of the tire and also increased the use cost of the vehicle.Along with the increasing of axle number, the steering distortion of high-speed run mode becomes deteriorate, even at a lower speed of 40km/h, vehicle may also lost direction control. More than that, wheel's wear and tear as well as use-cost increases accordingly, with the number of bridge increasing. Steering performance of heavy-duty vehicle has directly effect on vehicle agility manipulate stability and use economy. Optimization steering process requires all wheels working in the state of pure roll without slipping, or only little slippage. Or else large slippage will aggravate wheels' wear and tear. For over-length heavy-duty vehicle, only reasonable steering drive mechanism can meet vehicle's minimum steering radius need demanded by national standard.The better of all All Terrain Crane is that All Terrain Crane can adjust their center of mess's slip angle while turning direction, angular speed and angular acc- eleration in the course of turing transition, All Terrain Crane can also reduce turn radius of car when it turn around at low speed, vehicle enhance moving flexibility by this, all terrain crane also should have crab walk ability which can make it can fast close to the operation area or leave. Thus steering stability and mobility of all terrain crane be improved In this article The relationship of multi-axles steering and maneuvering stability is studied basing on all terrain truck crane as the prototype.The mathematical model of two and three degrees of freedom steering system are established on the base of theoretical analysis using the automatic control theory and the multi-body dynamic theory the computer simulation research of steering characteristic of multi-axles vehicle is made.(1) The article bsed on the automobile theory and the differential equation of vehicle's motion, the gain of the yaw velocity was developed. The paper studies the transfer function of transient response by means of MATLAB software, the characteristics of 2WS vehicle and 6WS vehicle in both time and frequency domain responding to front wheel step input were simulated.(2) On the basis of mathematical model, this paper utilizes MATLAB software to analyze steering performance in steady state and respond characteristic in the course of transition when inputing a step angle on front wheel under various working pattern, this paper also simulate the working situation under the mode of minimum-steering-radius(3) The computer simulation on controller control was analyzed and in research. Fuzzy controller and LGR was designed for the Semi-active suspension with fuzzy control method. And the fuzzy controler's parameter and control performance were carried out. The controller are designed which can improved the handling stability and improved the controller precision.(4) According to the requirements for all terrain crane, basising on the steering scheme confirmed and the characteristic of power steering system in all terrain crane, finally, the optimal control strategy of 6WS in all terrain crane is confirmed, which can make all terrain crane move flexible and handle steadily.This paper has put forward the systematic mathematical model of 6WS of a certain all terrain crane, simulation methods used and results offer the basis for the development of 6WS in a certain all terrain crane, the stratage of control and the design of system had raised is very impotant to the development of 6WS, it also has reference value for the research of multi-axle steering system in other vehicle.