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CONTROLS SYSTEM OF VEHICLE MODEL WITH FOUR WHEEL STEERING (4WS ...
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Short Description: Electro-hydraulic mechanism (e.g. Mazda 626 – 4WS). Electric mechanism (e.g. Honda E-4WS, .... wheels through gear ratios of steering boxes. ...
Content Inside: XIII Meunarodni naucni simpozijum Motorna Vozila i Motori International Scientific Meeting Motor Vehicles & Engines XIII Kragujevac, 04. - 06.10.2004 YU04017 P. Brabec*, M. Mal**, R. Vozenlek*** CONTROLS SYSTEM OF VEHICLE MODEL WITH FOUR WHEEL STEERING (4WS) Abstract: Four-Wheel Steering Rear Wheels Control. For parking and low-speed maneuvers, the rear Wheel steer in the opposite direction of the front wheels, allowing much sharper turns. At higher speeds, the rest wheels steer in the same direction as the front wheels. The result is more stability and less body lean during fast lane changes and turns because the front wheels don't have to drag non-steering rear wheels onto the path. KEY WORDS: Four-Wheel Steering, 4WS, Rear Wheels Control 1. INTRODUCTION Mainly in aviation and shipping industry, the scale models belong for many years to common methods of experiment implementation. For example, in aerodynamics of aviation structures, the aircrafts' scale parts or entire aircrafts have been used for experimental determination of aerodynamic characteristics and their optimisation. With the help of similarity theory, using this method, it is possible to obtain relatively accurate experimental results with low costs incurred. It is also possible to execute experiments, which would otherwise be entirely infeasible, verify function of even small-scale variations and modifications of the structure; all this can be done within a short time. Also a minimum risk experienced is essential, which would naturally accompany experiments that are otherwise feasible. These advantages as well as development of commercial sets of scale models have led to utilisation of this method even in the field of development of new resolutions in disciplines of vehicle design and intelligent transport systems design. In case of automotive industry, recent technologies have allowed going beyond this; thus, in addition to aerodynamics, which is focused mainly on the shape of vehicle body and the air flow along car body as well, it is possible, through accurate miniatures of structural parts of vehicles, to make a vehicle that is very similar to real car, including weight proportions and dynamic characteristics. 2. SYSTEM 4WS Contemporary rear axles allows for coincidental steering through the influence of variation of elastokinematic steering; rear wheels rotate, due to an influence of variation of vertical load of wheels (tilting), in the same direction as front wheels. Nevertheless, such a turn of rear wheels is very small and driver's will-independent. A disadvantage of this so-called passive steering system is that it operates even when driving in straight direction when single wheel of an axle hits surface irregularity (deterioration of directional stability). New generation of active steering systems distinguishes a need of steering of rear wheels for the reason of directional stability from a need of steering of rear wheels for the reason of cornering at slow speed. Therefore, the active system means that rear wheels are possible to be turned either coincidently or non-coincidently. The increase of the manoeuvrability when parking the vehicle is achieved by means of disconcordant steering, meanwhile the increase of the driving stability at higher speeds is achieved through concordant steering. *Pavel Brabec, Eng., Technical University of Liberec, Faculty of Mechanical Engineering, Hlkova 6, 461 17 Liberec, Czech Republic, pavel.brabec@vslib.cz ** Miroslav Mal, Assoc. Prof., Technical University of Liberec, Faculty of Mechanical Engineering, Hlkova 6, 461 17 Liberec, Czech Republic, miroslav.maly@vslib.cz *** Robert Vozenlek, Eng., Technical University of Liberec, Faculty of Mechanical Engineering, Hlkova 6, 461 17 Liberec, Czech Republic, robert.vozenilek@vslib.cz
