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Modelling and Simulation of Rapidly Changing Road Gradients

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)392-401
Number of pages10
JournalSAE International Journal of Passenger Cars - Mechanical Systems
Issue number1
DateAccepted/In press - 1 Apr 2016
DatePublished (current) - 5 Apr 2016
EventSAE 2016 World Congress and Exhibition - Detroit, United States Minor Outlying Islands
Duration: 12 Apr 201614 Apr 2016


In vehicle dynamics modelling, the road profile is generally treated in one of two ways; either the gradient is a property that changes over a length scale far greater than that of the vehicle's wheelbase, or as a very detailed road surface model for determining the behaviour of vehicle suspensions. Occasionally, for modelling the behaviour of off-road vehicles, step-climbing manoeuvres are modelled. We propose an extension the general ideas of these step-climbing models to a general, continuously varying road gradient model for cases where the distance over which the large gradient change occurs are of similar length-scale as the vehicle wheelbase. The motivation behind this work comes from a road gradient and vehicle mass estimation problem where it was noticed that very sudden gradient changes have a significant impact on the powertrain, but in a way that is not proportional to the attitude change of the vehicle. We present an analysis applicable to these cases where the road gradient change is substantially different from the vehicle attitude change. The analysis is built up from a very basic step climbing exercise to a general case solution for two dimensional longitudinal vehicle dynamics. Methods of handling road gradient and gradient change for modelling purposes are also discussed, and a method is proposed defines the gradient change as an input to the model (where applicable) as well as simply the instantaneous gradient at a point in space. The results of preliminary validation experiments for simple gradient change cases are shown. We discuss the implication of these road gradient transients to vehicle parameter estimation based on powertrain behaviour.

    Research areas

  • Commercial vehicle, automotive, simulation and modeling, vehicle dynamics, off-highway vehicles and equipment


SAE 2016 World Congress and Exhibition

Duration12 Apr 201614 Apr 2016
CountryUnited States Minor Outlying Islands
Degree of recognitionInternational event

Event: Conference

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    Rights statement: This is the author accepted manuscript (AAM). The final published version (version of record) is available online via SAE International at Please refer to any applicable terms of use of the publisher.

    Accepted author manuscript, 631 KB, PDF document


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