Simulation method of comparative evaluation of the agility of a passenger car when moving “forwards” and “backwards”
Janusz Kulma 1  
,   Zbigniew Lozia 1  
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Warsaw University of Technology, Faculty of Transport
Publication date: 2014-08-25
The Archives of Automotive Engineering – Archiwum Motoryzacji 2014;64(2):49–64
The objective of this study is to compare the agility of a specific motor vehicle (ability of the vehicle to follow paths having small radii of curvature) when moving “forwards” and “backwards”. These terms have been put here in quotation marks because their meaning depends on the point of view individually adopted. In this study, the vehicle is understood as moving “forwards” when the vector of the predefined vehicle velocity is pointing towards the vehicle front. The vehicle may also be said to move “backwards” when it is reversing and to move “forwards” when it is driven in any other gear. To accomplish the objective of this study, a simulation method was employed. Instead of the Ackermann model, a three-dimensional dynamic model was used where the tyre slip angles were taken into account. The vehicle manoeuvres simulated during the tests included vehicle drive along a path with a constant curvature radius on a road surface affording good adhesion, vehicle drive with a “saw-tooth” input applied to the steering wheel, and vehicle drive into a parking place parallel to a roadway edge. The vehicle speed was limited to 40 km/h because of the nature of the manoeuvres simulated (aimed at the evaluation of vehicle agility) and because it would be difficult to achieve higher velocities of the vehicle reversing in real conditions. The results obtained have shown significant differences in the vehicle behaviour when it moved “forwards” and “backwards”. Some of them are known to every experienced driver and this fact may rather be considered just confirmation of the usefulness of the simulation method adopted.
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