Methodology for Hazard Identification and Mitigation Strategies Applied to an Overtaking Assistant ADAS

We propose a methodology for analyzing the hazards and potential mitigation of faults and failures in an Advanced Driver Assistance System (ADAS) which is applicable to individual systems and subsystems of a larger automated vehicle implementation. To illustrate the methodology, we outline the structure of an notional overtaking assistant, considering that the system would not only need internal sensors such as global navigation satellite system (GNSS) receivers, map data, and other motion and localization sensors and external sensors such as radars, lidars, and vision systems but also access to cooperative positioning information through a wireless connected vehicular network in order to identify the location of oncoming traffic. Then, we perform the hazard analysis of this subsystem utilizing a combination of methods. For the vehicle level hazard analysis we use Hazard Operability Study (HAZOP) and the first step of System Theoretic Process Analysis (STPA), and for the overall safety analysis we use Failure Mode and Effects Analysis (FMEA) and the second step of STPA. An overtaking assistant for automated vehicles is considered a type of Advanced Driver Assistant System (ADAS) that assists a partially or fully automated vehicle with an overtaking maneuver consisting of acceleration and steering control during a double lane change. Crash data indicates that although only 19% of the US population inhabits rural zones, 54% of the vehicular crashes happen on rural roads [1], with a high number of those events occurring during an overtaking maneuver on two-lane rural roads. While such an overtaking assistant would help to minimize these collision events, no commercial product is yet available due in part to the challenge of defining what constitutes safe navigation in these systems. The analysis performed on the system is presented and is proposed for use as a general methodology to analyze hazards in any ADAS system or subsystem. The summary of the analysis results provided here include a list of hazards and mitigation strategies for the proposed two-lane rural road scenario.