Analyzing Driver Foot Behavior between Regenerative and Service Braking

Abstract

With the increase of electric vehicles on the roads, there is also an increase with vehicles that use regenerative braking (RB). This novel braking method differs from traditional service braking (SB) because RB decelerates the moment the driver releases the accelerator pedal and continues to actively brake if neither pedal is depressed. Since the vehicle actively decelerates when neither pedal is depressed in a vehicle with RB, we hypothesized that this would result in a difference in driver foot behavior. There were two pieces to explore this potential difference. The first piece was to explore time-based measures. The first measure was the time period from when the lead vehicle brake lights illuminate, to when the driver releases the accelerator pedal. The second measure was the time period from when the driver releases the accelerator pedal, to when the driver presses the brake pedal. When comparing RB and SB, there was no statistically significant difference for the first time-based measure. When comparing RB and SB for the second time-based measure, the high level of RB was statistically significantly different. The second piece was to code each video to label driver foot behavior based on a set of catego-ries. The 5th category (uncertainty - "wagging foot") was the only foot behavior appearing in all three conditions (n = 2, SB; n = 4, low RB; n = 6, high RB). The 8th category (brake tap, reposition to throttle, then brake press), only appeared in the high level of RB condition and appeared 9 times (33% rate). This study shows that RB results in differences in driver foot behavior when compared to SB in the time period between accelerator release and brake press. It also shows that RB results in drivers engaging in foot behavior indicating uncertainty.