Driving a car gives us a certain feeling. Driving another car returns a very differentexperience. If we could drive with closed eyes, we could nonetheless explain which vehicle itwas we were sitting in. Not only are there differences between sports cars and transporters orlimousines and trucks, but also it is possible to feel the different sensations from drivingtrucks of different manufacturers. It depends on the seat, the sitting position, the view, thesound, the performance, the brakes - and the steering feel.There are many ways how to describe a vehicle's steering feel. There are ISO-standards, suchas ISO/TS 20119 and ISO 14792 that generate characteristic values, there are subjective testsof 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 nearlyindescribable feelings has not been fully investigated yet. With a better understanding of thecorrelation between objective values and subjective experience, it may be possible to find ananswer 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 measuringgauges and let them measure impressions in their own words.Thus, in order to gather a standardized answer that can be evaluated, a questionnaire wasdeveloped. For this questionnaire the most important consideration was to facilitate the testdrivers 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 adouble interrogation process.When people express their feelings like they are accustomed to do, they will utilize a libraryof 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 psychoacousticswhich allows people describe how noise sounds to them. With this kind of evaluation - valueassigning procedure - a list of parameters comes to existence similar to that containing theinstrumental values. To explore the relation between the instrumental and non-instrumentalvalues, statistical methods are used.

“If touching is not a single perception but a plural, then its objects are a plurality, too.” (Aristotle)

For investigating steering feel, a very important part is how to measure what people feel. The hypothesis in the present research work is that steering feel, as perceived by human beings, can be allotted in dimensions. The steering feel of a certain vehicle can then be seen as a point in a space with multiple orthogonal dimensions. The aim is to find the dimensions that people use to perceive and describe steering feel, in order to define this non-instrumental space. This article describes two modes of evaluation, a manual mode anda mathematical mode using the statistical method of multidimensional scaling. Applying these modes, it has been possible to extract nine dimensions describing the steering feel of road vehicles.

There have been several investigations to find out how drivers experience a change in vehicle-handling behaviour. However, the hypothesis that there is a correlation between what the driver perceives and vehicle-handling properties remains to be verified. To define what people feel, the human feeling of steering systems was divided into dimensions of perception. Then 28 test drivers rated different steering system characteristics of a semi-trailer tractor combination in a moving base-driving simulator. Characteristics of the steering system differed in friction, damping, inertia and stiffness. The same steering system characteristics were also tested in accordance with international standards of vehicle-handling tests resulting in characteristic quantities. The instrumental measurements and the non-instrumental ratings were analysed with respect to correlation between each other with the help of regression analysis and neural networks. Results show that there are correlations between measurements and ratings. Moreover, it is shown that which one of the handling variables influence the different dimensions of the steering feel.

This work presents the evaluation of an experiment on the relationship between driver performance and vehicle handling quantities. Both of them are instrumental quantities, however, the former are driver dependent, the latter are only vehicle dependent. A moving base driving simulator was used to examine 16 truck-trailer-combinations. The driving of 28 test drivers in a special developed manoeuvre resulted in characteristic driver performance values evaluated of vehicle system quantities measured while driving. Stationary and dynamical ISO-handling tests resulted in handling quantities. The correlation by means of regression analysis between these driver performance values and the quantities of the ISO-handling tests are presented here as a step towards the mapping of steering feel.

There is not yet a standardised method to find mutual corresponding subjective and objective measurements. This paper describes how non-instrumental measurements (made by human measurement gauges) and instrumental measurements (made by measuring instruments) can be distinguished in quantities that are dependent of the vehicle, the driver's skills or the driver's individual preferences. Moreover, this paper shows the correlation between instrumental and non-instrumental measurements.

This paper presents an investigation about influencing the driver's behaviour intuitively by means of modified steering feel. For a rollover indication through haptic feedback a model was developed and tested that returned a warning to the driver about too high vehicle speed. This was realised by modifying the experienced steering wheel torque as a function of the lateral acceleration. The hypothesis for this work was that drivers of heavy vehicles will perform with more margin of safety to the rollover threshold if the steering feel is altered by means of decreased or additionally increased steering wheel torque at high lateral acceleration. Therefore, the model was implemented in a test truck with active steering with torque overlay and used for a track test. Thirty-three drivers took part in the investigation that showed, depending on the parameter setting, a significant decrease of lateral acceleration while cornering.

This paper shows for a heavy truck simulation model the advantages of an artificial understeering functionality realised by a PID controlled active front steering system based on linear calculated yaw rate error. The yaw rate error results from the difference between measured vehicle yaw rate and a linear calculated yaw rate based on steering wheel angle and vehicle speed. The integrated controlled system shows increased performances: The more linear-like behaviour together with a higher understeer gradient over a wide lateral acceleration range which increases safety especially in emergency conditions.