Automated heavy-duty vehicles have the potential to produce significant economic benefits with a driver in the lead vehicle and the remaining vehicles in an automatic tracking mode. This, however, requires that control issues in normal tracking and emergency operations be fully understood, and that automated control system at least have the ability to cope with well known phenomena arising from stability issues in heavy duty articulated vehicles. The solution will involve understanding the role of the lead truck (driver response and response of its control system) in assisting the trailing vehicles, and the development of control system for the trailing vehicles to provide stable longitudinal and lateral dynamics. This paper has analyzed some fundamental control issues that have to be treated in the transition from a human driver to an automated control system, and has focused on the role of lateral stability as the critical issue to guarantee vehicle safety in both tracking and emergency scenarios. It has emphasized the critical role of tire force saturation and steer angle limit as the two main nonlinear effects that must be thoroughly understood in developing appropriate controls, proposing simplified piecewise linear characteristics be used in design models. This is base on the development of adequate tire models, based on the Magic formula and the LuGre model. The LuGre dynamic tire model has the capability to capture the transient processes associated with tire friction and to include the effect of surface condition, tire normal load and the phenomenon of tire friction ellipsoid, and should get wider attention. Such models form the basis for the appropriate characterization of tire force distribution, the evaluation of actual and desired slip ratios, and the integration of brake and steering action in emergency situation when linear models of lateral dynamics may not be adequate. Conventional vehicle dynamic analysis was used to highlight the need to combine handling characteristics with limits posed by these nonlinearities and with the possibility of enhancing stability by such coordinated use of steering and differential brake.
Safety concerns in automatic control of heavy-duty articulated vehicles
Sicherheitsbetrachtungen bei der automatischen Steuerung von Schwerlast-Sattelkraftfahrzeugen
2004
15 Seiten, 16 Bilder, 26 Quellen
Conference paper
English
Safety concerns in automatic control of heavy-duty articulated vehicles
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