| The rapid development of economy requires the improvement of transport capacityand the highway transportation is an important part of transportation. So heavy truckswhich have lager capacity began to be applied. Because of its large loading capacity andlow transportation costs, tractor semi-trailer becomes more and more popular. However,due to its high center of gravity and narrow trade, tractor semi-trailer is easy to rolloverwhen it is turning. This will bring potential safety hazard. In recent years，many people didsome research on the rollover of tractor semi-trailer,but most of them only built the rigidmodel. They didn’t consider torsional compliance of the vehicle frame.At first the mechanics of rollover was analyzed. Some vehicle parameters was studiedon the influence of the rollover. Then a few of methods were present to improve the rollstability of tractor semi-trailer. In order to build the model easily and ensure its accuracy,some assumes and simplifies were made. the simple rigid tractor was first modeled. Thentorsional compliance of frame was considered. Tractor and semi-trailer were modeled,then they were connected by the fifth wheel. The simulation model was built inmatlab/Simulink too.Then on the basis of analysis of the mechanics of rollover and the method ofpreventing rollover of tractor semi-trailer, which is using the Anti-roll bars, the model wasresearched to design the controller. The load transfers is measured for knowing if thetractor semi-trailer became to rollover and the control strategy is designedIn the matlab/simulink environment, the models were simulated with the front wheelangle step input,fishhook input and in the conditions of double lane change. Still thesimple rigid tractor model was first simulated. Then the same methods was used in thesimulating of the torsionally flexible tractor The results were analyzed, which show thatthe control strategy can prevent the rollover of the rigid tractor or the torsionally flexibletractor.in all the conditions. |
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