Safety Analysis And Test Evaluation Of Safety Of The Intended Functionality Of Highway Pilot System

Traffic accidents are one of the major causes of human casualties worldwide.With the widespread use of autonomous driving technology,the number of traffic accidents has decreased significantly,but the issue of Safety of the intended functionality caused by the inadequate functionality of autonomous driving systems also arises.In January 2021,the United Nations Economic Commission for Europe(UNECE)issued the first regulation UN-R157 for Automated Lane Keeping Systems(ALKS),an L3 level autonomous driving system,proposing design requirements for the development of high-level autonomous driving systems,and the object of this paper is Highway Pilot(HWP),a subsystem of ALKS.First,Safety of the intended functionality of the HWP system,including the definition of HWP system related items,the definition of operational design conditions,and the construction of the initial architecture of the HWP system as the theoretical basis for Safety of the intended functionality analysis of the HWP system.Based on the guide words of Hazard and operability analysis(HAZOP)method to derive the possible hazardous behaviors of HWP system,and based on Safety of the intended functionality analysis process proposed by t Safety of the intended functionality standard ISO 21448,the hazard analysis and risk assessment of HWP system are conducted to get the hazard events that are related to Safety of the intended functionality and the risk is unacceptable.The hazard events related to Safety of the intended functionality and unacceptable risk are obtained,and the top event of the cause-effect tree analysis method is done with a hazard event,and the performance limitations and trigger conditions of the HWP system are obtained in a layer-by-layer refinement.Second,based on the expert experience and data to generate typical highway/urban expressway straight cut-in logic scenarios for HWP system.Firstly,based on the expert experience,we construct the typical highway/city expressway cut-in functional scenario and abstract scenario of HWP system,and define the key moments and scenario elements of the cut-in scenario,use UAV to collect the video data of Chinese drivers’ vehicles that meet the operational design conditions of HWP system,process the video data to get Aerial Dataset for China Congested Highway & Expressway(AD4CHE),and use the rule-based method to extract the cut-in scenarios from the aerial dataset,extract the value range of scenario elements in the logical scenarios of HWP system,fit the change trend among the scenario elements,and generate the typical highway/city expressway straight cut-in logical scenarios of HWP system by combining the trigger conditions.Thirdly,Safety of the intended functionality testing of the HWP system.Generate specific scenarios based on the range of scenario elements taken in the logical scenario and the fitting relationship between scenario elements,and discretize the range of scenario elements taken.Based on the trigger conditions and the closed-field test method,design the closed-field test cases,the expected functional safety test process of HWP system,and complete the expected functional safety test of HWP system.Finally,Safety of the intended functionality the HWP system is quantitatively evaluated.Based on the design guidelines of ALKS system and the definition of relevant terms of HWP system,Safety of the intended functionality evaluation dimensions of HWP system are extracted and the framework of quantitative evaluation system is constructed;the operational safety assessment metrics are summarized and classified based on domestic and foreign literature,and the quantitative evaluation system is completed based on the physical formula and usage conditions of the operational safety assessment metrics;the cut-in scenario with the same speed interval between the main vehicle and the target vehicle in the closed field test case is extracted from the AD4 CHE dataset The results of the operational safety assessment metrics are calculated by extracting the cut-in scenarios in the same speed range of the main vehicle and the target vehicle from the AD4 CHE dataset,using a linear fitting method to obtain the fitting trend between the trigger conditions and the operational safety assessment metric,comparing the safety of the Chinese driver and the HWP system under a typical highway/city expressway straight cut-in test case,and judging whether Safety of the intended functionality of the HWP system meets the design requirements.This paper supports Safety of the intended functionality safety analysis of high-level autonomous driving systems,generates typical test scenarios,and quantitatively evaluates Safety of the intended functionality of autonomous driving systems.