On the Effects of State Information on Driver-Vehicle Performance in Car Following

A control stick with a built-in kinesthetic-tactile compensatory display, which was used to give a driver information concerning his state with respect to the nearest lead vehicle, was tested in several full-scale car-following situations. System performance was evaluated for several display excitation signals by means of average tracking measures (headway variance and relative velocity variance), system dynamic response as evidenced by describing-function models, and subjects' opinion ratings. The average tracking performance and dynamic response of a driver-vehicle system, as well as a driver's workload, were substantially modified by providing him with aiding information. More consistent dynamic performance among driver-subjects was obtained, and it was established that part of the driving workload can be effectively shared by an automatic system.