Ground Risk Assessment of UAV Operations Based on Horizontal Distance Estimation under Uncertain Conditions

Yang Liu,Zhi Wang,Xuejun Zhang,Chang Liu,Ziang Gao,Ana C Teodoro

doi:10.1155/2021/3384870

Abstract

In this paper a ground safety assessment model is introduced based on the probability estimation of possible impact positions when unmanned aerial vehicle (UAV) crashes on the ground. By incorporating the random uncertainties during the descending process, risks associated with UAV’s ground crash are estimated accurately. The number of victims on the ground per flight hour is selected as the indicative index to evaluate the risk levels of the corresponding ground area. We mainly focus on the analysis of uncertainties that usually appear in drag coefficient which would generate a great amount of effects on the travelled horizontal distance from the failure point to the impact point on the ground, which further influences the possible impact positions. The drag force in the air, failure velocity of a UAV, and wind effects in the local area are all considered in the proposed model, as well as ground features, including sheltering effects on the ground, UAV parameter settings, and distribution of local population. Uncertainties in drag force when a UAV descends, UAV’s initial horizontal and vertical speeds at failure point, and local wind patterns are all considered as the indispensable factors in the proposed model. Especially the probability of fatality once hit by the UAV’s debris is explored to make the safety assessment more reliable and valuable. In the end, the actual UAV parameters and official historical weather data are used to estimate the risks in a real operation environment when a failure event happens at a legal flying height. Experimental results are given based on different types of UAVs and random effects in the descent. The results show that all the operations of all kinds of UAVs selected in the validation are so dangerous that the safety of people on the ground cannot be guaranteed, whose value is much bigger than the manned aircraft safety criterion 10−7.

Highlights

Unmanned aerial vehicle (UAV) is the fastest growing sector of the aviation industry, which has become the focus of many commercial and civilian applications including delivery of goods, search and rescue, disaster relief, infrastructure monitoring, precision agriculture, public safety, and weather monitoring [1,2,3].Especially because of the UAV’s strong line-of-sight connection links, fast and flexible deployment and mobility, they have been widely used in various civil Internet of ings (IoT) applications
We mainly focus on the analysis of uncertainties that usually appear in drag coefficient which would generate a great amount of effects on the travelled horizontal distance from the failure event point to the impact point on the ground. e drag force in the air, failure velocity of a UAV, and wind effects in the local area are all considered, as well as ground features, including sheltering effects, UAV settings, and distribution of local population
We have presented a method to assess the ground risks caused by the crashed UAVs, in which the possible impact positions are estimated first by deducing the probability dense function (PDF) of travelled horizontal distance from the UAV’s failure point to the ground impact point. en by considering the uncertainties that usually appear in the UAV’s descending process and local wind patterns, the obtained risk values would be more practical and valuable, especially when the real UAV parameters are used as well as the ground features

Summary

Introduction

Unmanned aerial vehicle (UAV) is the fastest growing sector of the aviation industry, which has become the focus of many commercial and civilian applications including delivery of goods, search and rescue, disaster relief, infrastructure monitoring, precision agriculture, public safety, and weather monitoring [1,2,3]. Because of the uncertainties in the airspace and limited flying resources of UAVs themselves, a failure event often happens for UAVs at some specified altitude It will introduce a lot of safety hazards to the people and properties on the ground, which further results in the imposition of a significant amount of operational restrictions on them [5,6,7]. Because in this paper an actual scenario is adopted, many random uncertainties should be taken into account in the drag force, such as the randomness in initial horizontal and vertical speed of UAV at the failure point and even the wind effects in local areas. The widely accepted value given by FAA is 10−7, which can be listed as a reference for UAVs’ operations

Ground Safety Assessment and Risk Estimation

Experiments and Case Study

Conclusions