A Study on Parallel Routes Lateral Separation for Urban Logistics UAV

To improve the operational safety of urban logistics with unmanned aerial vehicles (UAV) in high-density regions, lateral separation (LS) for UAVs in parallel routes is studied. Specifically, the conflict frequency and collision probability are taken into account in the LS model and the LS for UAVs meeting the safety requirements is determined. The target level of safety (TLS) is set and the criteria of conflict is defined as the lateral distance of adjacent UAVs is less than the required LS. Then, the frequency of conflict can be counted by using the real operation data of UAVs. An urban logistics system using UAVs is simulated, comprehensively incorporating the UAVs' performances, flight flow, airspace volume, deviation probability, deviation angle, conflict detection and resolution, etc. The Monte Carlo method is introduced to assess the probability of collision by simulating the scenarios where a UAV has a random accidental deviation causing conflict with the adjacent UAVs under a given probability. A total of 5.1 million rounds of simulations are performed and the LS ranges from 1 meter to 51 meter. The results show that: ①50 302 violations are observed; ②the probability density function (PDF) of collision and the LS value fit an exponential distribution, well; ③applying a proper lateral separation would be a potential risk mitigation strategy for reaching TSL. In summary, the required lateral separation for UAVs in the urban city is suggested as 33 m by comparing the accepted TSL with the residual risk calculated by the fitted PDF.