F2008-02-040
A Novel Method for Objectifying the Physiological Stress of the Car Driver while Braking
The control elements in motor vehicles must be designed such that the operator is protected to the greatest possible extent from physiological overtaxing and signs of fatigue of the muscular system during the operation of the car. If this criterion is not fulfilled, or if the driver even suffers from permanent pains while driving, the vehicle is felt to be uncomfortable. The risk of overtaxing occurs primarily during operations which last only a short time, but which require physical exertion. On the other hand, signs of fatigue generally show up during operations which require comparatively low but monotonous and long-lasting physical efforts. The possibilities known so far of detecting such stresses, and of establishing concrete connections between the stresses and their effects on the operator still leave many questions open at present. This paper describes a complex interdisciplinary methodical approach which has the potential to generate new findings and development tools for designing man-machine interfaces. This approach aims at fully objectifying those parameters which exert an influence on the physiological stress of the driver while driving by means of the braking process. The basic prerequisite for realising this challenge is provided by the combination of driving physics, human physiology and human psychology, an interdisciplinary constellation not known so far yet. On the one hand, the approach includes an analysis of the interface parameters prevailing on the carīs side by using specially developed test vehicles. These vehicles are equipped with fully active servohydraulic actuators which permit the numerous variations of the pedal and braking features. The second main focus of our investigations lies on the measurability of the driverīs response. One method established in the field of motion sciences for detecting and marking the function and stress of muscles and muscle chains is the Surface Electromyography (EMG). This non-invasive technique allows the myoelectric potentials generated through muscular activities, just as the stress lying on the driver to be analysed both while the vehicle is standing still or moving. The investigations were carried out on a number of test persons to study different muscles and groups of muscles in their lower and upper extremities and in their trunk while the braking pedal was applied under various conditions. The following parameters were taken into account: the type of car (upper class sedan car / sports car / transporter), the characteristic features of the brake pedal, the braking mission (braking at destination/ emergency stop), and the seating position. The paper presents some selected results obtained in our research work: Regarding the above-mentioned parameters, it is clearly shown that they have an influence on the control behaviour of the human body during the braking action. Some differences can be stated as far as the intensity of the muscular activities are concerned, but also regarding the selection of the muscles involved in these activities. Furthermore, on the basis of the changes of these connections stated over a longer stress period, it is possible to draw conclusions about the effects of fatigue.
This abstract is supplemented by a PDF, which can be viewed here.
Poster presentation: Man-Machine-Interaction