The Shorter Takeover Request Time the Better? Car-Driver Handover Control in Highly Automated Vehicles

The future development of fully automated vehicle cannot be predicted yet. CarCars-driver handover control need be existed in a certain period, but it is not well understood. The present study is to gain deeper insight into carCars-driver handover control in the highly automated vehicle by investigating the effects of mode transition, the time of transition to takeover request (TTR-time) and take over request time (TOR-time). Two experiments were conducted via driving simulator. Experiment 1 invited twenty participants to analyze the influence of TOR-time when resuming control. Experiment 2 recruited forty participants to further explore the effects of mode transition, TTR-time and TOR-time with a 2 * 2 * 2 mixed design. The shorter TOR-time resulted in less takeover reaction time but worse quality. Six seconds was the balance point between less takeover reaction time and higher handover control quality. In addition, the shorter TTR-time aggravated the significant difference of takeover reaction time caused by TOR-time, but the longer TTR-time abridged the significant difference and improved the attitude towards TOR-time during transition from level 3 to level 2 of automation. If the TOR-time is needed to be reduced in the design for acute threats, no less than six seconds would be better. If the future autonomous vehicle involves the mode transition of automation levels, designerDesigners and engineer also should take the time of mode transition to takeover request into account. These findings provide practical implications for the takeover control design of highly automated vehicles.