Responses of Vehicular Occupants During Emergency Braking and Aggressive Lane-Change Maneuvers

Abstract

To validate active human body models for investigating occupant safety in autonomous cars, it is crucial to comprehend the responses of vehicle occupants during evasive maneuvers. This study sought to quantify the behavior of midsize male and small female passenger seat occupants in both upright and reclined postures during three types of vehicle maneuvers. Volunteer tests were conducted using a minivan, where vehicle kinematics were measured with a DGPS sensor and occupant kinematics were captured with a stereo-vision motion capture system. Seatbelt loads, belt pull-out, and footrest reaction forces were also documented. The interior of the vehicle was 3D-scanned for modeling purposes. Results indicated that seatback angles significantly affected occupant kinematics, with small female volunteers displaying reduced head and torso movements, except during emergency braking with a upright posture seatback. Lane-change maneuvers revealed that maximum lateral head excursions varied depending on the maneuver's direction. The study concluded that seatback angles were crucial in determining the extent of occupant movement, with notable variations in head and torso excursions observed. The collected data assist in understanding occupant behavior during evasive maneuvers and contribute to the validation of human body models, offering essential insights for enhancing safety systems in autonomous vehicles.

Keywords: evasive maneuvers; midsize male; reclined; small female; upright; volunteer.

Figure 1

Test vehicle and two seating postures. (a) Test vehicle and DGPS; (b) upright seatback angle (23 deg); (c) reclined seatback angle (43 deg).

Figure 2

Test vehicle driving path and potential onset area of the evasive maneuvers.

Figure 3

Time histories of vehicle kinematics during evasive maneuvers. (a) Emergency braking maneuver; (b) left lane-change maneuver; (c) right lane-change maneuver.

Figure 4

Measurement of occupant excursion. (a) markers for stereo-vision motion tracking, (b) example of motion tracking results for goggle.

Figure 5

Measurement of occupant excursion. (a) Coordinate systems for vehicle and footplate load cell; (b) H-point measurement procedure.

Figure 6

Setting up body coordinate systems. (a) head and torso coordinate systems, (b) definition of head and torso rotation angles.

Figure 7

Distribution of head and torso excursions of volunteers during evasive maneuvers. The left and right sides of each box represent the 25th and 75th percentiles, respectively. The vertical line inside the box indicates the median. Whiskers extend from the interquartile range (IQR) to the furthest observation within 1.5 times the IQR. Observations beyond this range are indicated by red cross symbols. (a) Braking; (b) left lane change; (c) right lane change.

Figure 8

Volunteer response corridor during braking maneuvers. (a) Upright male; (b) upright female.

Figure 9

Volunteer response corridor during braking maneuvers. (a) Reclined male; (b) reclined female.

Figure 10

Individual and average head and torso kinematic trajectories during braking maneuvers.

Figure 11

Belt force and foot plate force measured during braking maneuvers. (a) Upright male; (b) reclined male; (c) upright female; (d) reclined female.

Figure 12

Occupant response during left lane change. (a) Upright male; (b) upright female; (c) reclined male; (d) reclined female.

Figure 13

Occupant response during right lane change. (a) Upright male; (b) upright female; (c) reclined male; (d) reclined female.

Figure 14

Individual and average head and torso kinematic trajectories in lane-change maneuvers. (a) Left lane change; (b) right lane change.

Figure 15

Belt and foot forces during left lane change. (a) Upright male; (b) reclined male; (c) upright female; (d) reclined female.

Figure 16

Belt and foot forces during right lane change. (a) Upright male; (b) reclined male; (c) upright female; (d) reclined female.

Figure 17

Results of linear regression analysis for maximum excursions. (a) Braking; (b) left lane change; (c) right lane change.