Development and Application of a Functional Model to Vehicle Development

The use of a functional model in the development of vehicle ride and handling characteristics can provide significant information to the engineer to aid and shorten the development process. This approach forms part of the new vehicle development strategy currently being developed at Lotus Engineering.

The paper presents a description of a functional model that has been developed and used in the evaluation of vehicle ride and handling characteristics. The basic construction of the model is described and output is validated against vehicle test data. A case study shows how the model can be used in conjunction with vehicle testing to identify particular vehicle performance characteristics and provide potential solutions.

The functional model makes use of global vehicle characteristics such as compliance steer effects and bump steer characteristics, rather than modelling individual suspension components. This reduces the number of parameters in the model and allows the engineer to conduct “what if” investigations, changing characteristics that are familiar to the development engineer. Once the required characteristics have been defined, then more detailed models can be used to identify how component changes can be made to provide the desired characteristics.

The paper concludes with an illustration of how this type of modelling can be used in the development process.