The paper presents models of car dynamics with varying complexity. Joint coordinates and homogenous transformations are used to model the motion of a car. Having formulated the models of the car, we discuss the influence of the complexity of the model on numerical efficiency of integrating the equations describing car dynamics. Methods with both constant and adaptive step size have been applied. The results of numerical calculations are presented and conclusions are formulated.
Two algorithms which allow one to take an uneven road surface into account in the vehicle dynamics analysis are presented in the article. Their essence is to determine the position of the contact point of the tire model with the uneven road surface. According to the concept of the authors, the names of the algorithms are to refer to the essence of the matter of the procedures assumed. The first of them -named Plane -can be used while considering the continuous model of the surface obtained by use of "the bicubic interpolation" taken from computer graphics, and the second one -named 4Points -in the case of the discrete model of this surface, developed especially for needs of the methods presented. In the work, it is assumed that only continuous changes of the road profile, without its possible abrupt changes, e.g. in form of a transversely placed threshold of sharp edges, can be considered. Therefore, the mapping of the road surface, obtained in the case of including its both models, is smooth. The developed algorithms are used to analyze dynamics of a technical rescue vehicle which can drive in terrain conditions.
Computer simulations of vehicle dynamics become more complex when a vehicle movement takes place on the uneven road surface. In such a case two problems must be solved. The first one concerns a way of road surface modeling, and the second one a way of precisely determining a place of interaction of reaction forces of the road on the vehicle wheels. In this paper triangular irregular networks (TIN) surface was used for modeling surface unevenness, and the author’s algorithm based on the efficient kd-tree data structure was developed for determining a place of an application road surface reaction forces. For calculating the reaction forces including rolling resistance force the Pacejka Magic Formula tire model was used. The solution presented in the paper is computing efficient and for this reason it can be used in the in real-time simulations not only for a vehicle dynamics but for any objects moving over an uneven surface road.
Driver comfort improvement by a selection of optimal springing of a seat Poprawa komfortu kierowcy poprzez dobór optymalnego resorowania fotela Abstract An optimal way to select parameters of a driver' s seat of a special vehicle, which contributes directly to an increase in driving comfort is presented in the work. A mathematical model of the vehicle was formulated by using of joint coordinates and homogenous transformations. A maneuver of driving over obstacles in a form of a speed bump of different heights and lengths is presented. A subject of the investigations was to select such damping parameters and driver' s seat stiffness to minimize amplitudes of vibrations present in this subassembly. An influence of a form of an objective function and a selection of decisive variables on quality of the optimization results obtained was analyzed.Keywords: active suspension, drive comfort, dynamic optimization, computer modeling Streszczenie W pracy przedstawiono sposób doboru optymalnych parametrów fotela kierowcy pojazdu specjalnego, który bezpośrednio przyczynia się do zwiększenia komfortu jazdy. Model matematyczny pojazdu sformułowano korzystając ze współrzędnych złączowych i przekształceń jednorodnych. Przedstawiono manewr przejazdu przez przeszkody w postaci progów zwalniających o różnej wysokości i długości. Przedmiotem badań było dobranie takich parametrów tłumienia i sztywności fotela kierowcy, aby zminimalizować amplitudy drgań występujące w tym podzespole. W pracy skoncentrowano się na analizie wpływu postaci funkcji celu oraz doboru zmiennych decyzyjnych na jakość uzyskanych wyników optymalizacyjnych.Słowa kluczowe: aktywne zawieszenie, komfort jazdy, optymalizacja dynamiczna, modelowanie komputerowe
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