Abstract
Keywords - Heavy Truck, Steering Feel, Semantic Differential, Correlation, Field Test
Driving a car gives us a certain feeling. Driving another car returns a very different experience. If we could drive with closed eyes, we could nonetheless explain which vehicle it was we were sitting in. Not only are there differences between sports cars and transporters or limousines and trucks, but also it is possible to feel the different sensations from driving trucks of different manufacturers. It depends on the seat, the sitting position, the view, the sound, the performance, the brakes - and the steering feel.
There are many ways how to describe a vehicle's steering feel. There are ISO-standards, such as ISO/TS 20119 and ISO 14792 that generate characteristic values, there are subjective tests of automotive magazines, and there are opinions of test and race drivers. But exactly there, between the pure objective tests and the subjective impressions that are difficult to describe, exists a gap. This relationship between instrumentally measured numbers and nearly indescribable feelings has not been fully investigated yet. With a better understanding of the correlation between objective values and subjective experience, it may be possible to find an answer on which parameters can manipulate the feelings.
This paper is on an investigation about finding a correlation between instrumental values (values measured by instruments or calculated from those) and non-instrumental values (values obtained by human impressions). The idea is to use drivers as human measuring gauges and let them measure impressions in their own words.
Thus, in order to gather a standardized answer that can be evaluated, a questionnaire was developed. For this questionnaire the most important consideration was to facilitate the test drivers with their own languages. Therefore, the questions were developed in the test drivers' native language. The characteristic words were chosen corresponding to the results of a double interrogation process.
When people express their feelings like they are accustomed to do, they will utilize a library of expressive words instead of numbers. Thus the measuring results will have that character, too. By using the semantic differential method, expressions can be translated into numbers. The semantic differential method is a well-known method especially in psychoacoustics which allows people describe how noise sounds to them. With this kind of evaluation - value assigning procedure - a list of parameters comes to existence similar to that containing the instrumental values. To explore the relation between the instrumental and non-instrumental values, statistical methods are used.