Raccolta casi Working Model, visualNastran & SimWise - Three wheel vehicle dynamics

Contatto Editoriale:
Paolo Lista, Lista Studio srl®
Borgo Belvigo 33, 36016 Thiene Vi ITALY
tel/fax 0445,372479 o info@lista.it

For decades two and four wheel vehicles have been the most important means of people transport by road. Honda and Mercedes are now exploring new technical solutions especially in the field of three wheel vehicles. In this kind of vehicles the front frame is linked to the rear frame by a spatial mechanism. The different geometry of mechanism changes the position of the instant rotation center of the front frame. The principal aim of these researches is to increase safety, handling and to merge the stability typical of four wheel vehicles and the manoeuvrability/compactness of two wheel vehicles in only one kind of vehicle. The most followed way to realize this merging is to build a three wheel vehicle characterized by the capability of rolling.

Please click here to download a 1MB AVI file (compressed with WinZip) with the animation of this three-wheel vehicle

Prof. Cossalter’s team at University of Padua is examining the dynamics of this kind of vehicle and investigating the most important design parameters with the final target of providing strong indications necessary to the building of a first prototype.

According to the graduating student: "Our model is characterized by two principal frames. The front frame consists of the front wheel, forks and main structure, with a rigidly attached rider. The rear frame consists of the two rear wheels, the engine and the structure which support both of them. The front frame roll around the rear frame which doesn’t roll.

In our opinion, the most interesting field of research is to experiment different mechanism linking the front to the rear frame. In particular, by changing the kinematics, we translate and rotate the front frame’s roll axle obtaining very different vehicle behaviors.

We have used SolidEdge parametric features to generate many models, then in little time we have carefully assembled them. The model, which has sprang out, has been read by to Working Model integrated in Solid Edge.

In Working Model we have provided the vehicle with a mathematical tire model using one force and two torques for the front wheel, and only one force for the two rear wheels. Lateral tire force is proportional to the sideslip and to the wheel roll, whereas the two torques compute the moving of the contact point between tire and ground.

To test the vehicle’s performance and behavior we have also provided it with a proportional-derivative-integrative control. This has been realized by using the OLE Automation capability of Working Model: an external Visual Basic program gives the input to the steering torque. The control calculates torque value following a cubic spline interpolated trajectory. Various maneuvers have been implemented. The control system drives all vehicles trough the same trajectory, and we measure their performances evaluating vertical and lateral tire loads, steering torque, roll and yaw velocity and others."

According to Prof. Cossalter: "In short time, we have obtained many results, and we think others will be reached by pursuing our researches. We have been pioneers in using Working Model in Europe and our intentions are to cooperate to improve the software either for research or for teaching purposes."

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