The work discussed in this report is a continuation of the studies in MOU 252 and the discussions in a preceding report, UCB-ITS-PRR-97-4 (ST 971023). This report reviews the effects of certain operational parameters on the post-impact vehicle trajectories. Simulations of vehicle-following collisions show that large lateral offset and large initial spacing can result in significant path deviations or vehicle rotation and cause quick departure from the original traveling lane. The speed-differential or delta-V in collision appears to be a significant factor of the collision outcome in typical highway operations, as reflected in the large initial-spacing cases. The results also indicate that without control actions, the vehicles involved in a collision can be out of their lanes within 1 to 3 seconds. Several maneuvres are proposed to examine the feasibility of controlling vehicle motions during or after collisions. These maneuvres involve the use of steering and/or braking inputs on one or both vehicles. The results demonstrate lane-change or lane-keeping functions can be accomplished in the representative scenarios. An emergency braking function, if implemented, will be desirable to reduce the vehicle speed and their traveling distance. The understanding of vehicle motions in collisions is an important element in evaluating the safety hazards and benefits of automated vehicles. The use of two-dimensional crash models allows the examination of lateral and rotational movement. These simulations enable the assessment of operational parameters as well as the control inputs in crash conditions. A continuation of this work should include the implementation of a closed-loop control model with the crash and dynamic models. Efforts in developing a model with similar features for multiple vehicle collisions are also considered. (A)
Abstract