Due to continuously increasing driving speeds of tractors, the driving dynamics aspects gain more and more importance. To recognize critical vehicle behaviour and inadequate design at an early stage of development, multibody simulation models are used, most of them are focused on passenger car tyres and are limited in their use for simulation of large, soft tractor tyres. Thus at the University of Hohenheim a transient model for agricultural tyres was developed and applied to a multibody model of a of a Fendt 509 C agricultural tractor. Its basics are explained in this article. Besides that, the test stands used for parameterisation and model verification are presented as well as some verification results. Finally, the multibody model of the vehicle and its validation using a test vehicle are introduced. For the calculation of the three dimensional transient tyre force and torques, the Hohenheim Tyre Model was applied to the vehicle model. The tyre model calculates the relative movement between the tread and the rim and uses it as an input for spring - damper systems. As it is a point contact model, forces occurring during the rolling over obstacles can not be calculated. Since the modelling approach is physical, an extension of the model to a more detailed mechanical model is possible. However, this would extend the calculation effort and duration as well. The short calculating time - realtime factor far below 1 at a calculation frequency of 500 Hz - is another attribute of the Hohenheim Tyre Model. The number of model parameters is rather low and all have a physical background. They can be determined on university's test stands, which also were used for model verification. The multibody model of an agricultural tractor presented in this article was validated by various handling tests and shows good results. Consequently, it can be used as a basis for analysis of driving dynamics of tractors and for further vehicle improvements.
Driving dynamics simulation of agricultural tractors using the Hohenheim tyre model
Fahrdynamiksimulation von Ackerschleppern unter Einsatz des Hohenheimer Reifenmodells
2007
16 Seiten, 15 Bilder, 12 Quellen
Conference paper
English
Driving dynamics simulation of agricultural tractors using the Hohenheim Tyre model
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