An Open Simulation Approach to Identify Chances and Limitations for Vulnerable Road User (VRU) Active Safety

Abstract

Objective: It is commonly agreed that active safety will have a significant impact on reducing accident figures for pedestrians and probably also bicyclists. However, chances and limitations for active safety systems have only been derived based on accident data and the current state of the art, based on proprietary simulation models. The objective of this article is to investigate these chances and limitations by developing an open simulation model.Methods: This article introduces a simulation model, incorporating accident kinematics, driving dynamics, driver reaction times, pedestrian dynamics, performance parameters of different autonomous emergency braking (AEB) generations, as well as legal and logical limitations. The level of detail for available pedestrian accident data is limited. Relevant variables, especially timing of the pedestrian appearance and the pedestrian's moving speed, are estimated using assumptions. The model in this article uses the fact that a pedestrian and a vehicle in an accident must have been in the same spot at the same time and defines the impact position as a relevant accident parameter, which is usually available from accident data. The calculations done within the model identify the possible timing available for braking by an AEB system as well as the possible speed reduction for different accident scenarios as well as for different system configurations.Results: The simulation model identifies the lateral impact position of the pedestrian as a significant parameter for system performance, and the system layout is designed to brake when the accident becomes unavoidable by the vehicle driver. Scenarios with a pedestrian running from behind an obstruction are the most demanding scenarios and will very likely never be avoidable for all vehicle speeds due to physical limits. Scenarios with an unobstructed person walking will very likely be treatable for a wide speed range for next generation AEB systems.

Issues and challenges for pedestrian active safety systems based on real world accidents

“…Approaches based on numerical simulation have been explored to assess the effect of systems in various accident scenarios. These scenarios are provided from in-depth crash investigations and are simulated using simple models (Rosén et al, 2010;Seiniger et al, 2013). More complex methods (probabilistic methods as Monte Carlo) expand the scenarios by slightly varying the initial pre-crash conditions in order to cover a wider range of crash configurations (Lindman and Tivesten, 2006).…”

Driver models for the definition of safety requirements of automated vehicles in international regulations. Application to motorway driving conditions

“…TTC-based models have been used in safety evaluations for active safety of Advanced Driver Assistance Systems (ADAS) using experimental data, as in the work of Seiniger et al ( Seiniger et al, 2013 ). However, in contrast with ADAS systems which should intervene at the last moment in an emergency, AVs are responsible to avoid emergencies, when possible, by driving defensively.…”

Intersection AEB implementation strategies for left turn across path crashes

“…Additionally, the angle between the sight line (side midpoint to sensor origin) and the normal vector of the side was 45 or less. The brake delay time of the brake system was 150 ms and the brake jerk was 28 m/s 3 , representing a mid-class car (Edwards et al 2014;Seiniger et al 2013). Brakes were applied to reach maximum deceleration with the available road friction coefficient, which was also assumed to be available for the AEB algorithm.…”