Quantifying the difference between intention and outcome in driving performance

Abstract

The extent to which drivers control their vehicles according to their intentions is a critical problem in driving safety. We quantify the difference between a driver’s own intentions and the actual operations from observations of driver performance.Typical driving is governed by two types of processes: proactive and reactive control. In Proactive control, the driver prepares and executes actions in a timely manner ahead of future events, whereas in reactive control the driver responds directly to environmental stimuli. A state in which the relative amount of reactive control is high implies that the driver is busy responding to the surroundings and has difficulty attending to future events.Thirty active drivers participated in on a pylon slalom task, driven on a test track, that demanded rigorous control actions on a predefined course. The vehicle dynamics and driver actions on the vehicle controls were analyzed to quantify the proactive and reactive processes.Based on three indices related to amount of compensation in steering, proactive automatization and steering onset distance, we showed that the ratio of proactive to reactive control could be computed from the driver’s operations. The linear summation of the three indices, referred to as the reactivity index, can quantify the difference between driver intention and actual operations.Quantifying a driver’s ability to control the driving situation would be highly useful for deciding whether the driver should continue driving. The reactivity index could be used in various advanced driver-assistance systems (ADAS) to monitor driver status.