Skin Conductance Acquisition from Different Hand Sites: Towards an Instrumented Steering Wheel

Minimally invasive Driver Monitoring Systems (DMSs) can be designed by instrumenting the car steering wheel with sensors, to collect observations about the driver's psycho-physical status. Among the available options, this paper considers the use of dry electrodes integrated into the wheel, to acquire the skin conductance (SC) signal of the driver. Such signal, in fact, is deemed suitable to reflect the stressed or relaxed condition of the driver, which may have an impact on the probability of accident. As the driver may unpredictably change the position of their hands on the wheel, during driving and maneuvering, different sensor locations are considered. Tests involving pairs of fingers and hand palm of the same hand or different hands are performed, and the correlation among the signals acquired is evaluated, to estimate the degree of similarity and ensure that the meaningful content of the signal is preserved, irrespective of the specific measurement sites used. The results, though preliminary, show that a correlation greater than 0.80 is obtained for the majority of involved subjects in tests performed on pairs of fingers, irrespective of the hand used, and for electrodes located on a pair of fingers and on hand palm of different hands. Smaller and more variable correlation values are obtained considering electrodes located on a pair of fingers and hand palm of the same hand. While the influence of motion artifacts is to be acknowledged, this last result deserves further investigation.