Bio-signal indices to evaluate driver stress of automatic platooning

To reduce amount of CO₂ emission and improve efficiency of commodity distribution, a highway transportation system of automatic platooning is developing by applying closed gap distance control to trucks reducing their large air resistance. However, driver stress intensity during automatic platooning has to be evaluated, since driver stress occurs by the closed gap distance. In the paper, bio-signal indices of surface electromyogram (sEMG) of masseter muscle and perspiration rate of palm are proposed to evaluate driver stress intensity during automatic platooning. In virtue of a universal driving simulator, the bio-signals of subjects were measured in virtual traffic environment of automatic platooning. By the analysis of the bio-signal indices, it is found that driver stress intensities sharply increase by the sequence of trucks distances of 12, 8, and 4 meters during automatic platooning, and analytical results show that the driver stress intensities in trucks distances of 4 and 8 meters of automatic platooning mode are apparently larger than the driver stress intensities in normal driving mode.