Safe Schedule Verification for Urban Air Mobility Networks with Node Closures

TL;DR

This paper develops a linear programming-based method to verify the safety of Urban Air Mobility schedules under vertiport closure scenarios, ensuring UAVs can find safe alternative landings.

Contribution

It introduces necessary and sufficient safety conditions for UAM schedules and an efficient LP algorithm that handles uncertainty and scales to large networks.

Findings

Algorithm verified safety for networks with up to 1,000 UAVs.

Uses properties of totally unimodular matrices for efficiency.

Handles uncertain travel times between vertiports.

Abstract

In Urban Air Mobility (UAM) networks, takeoff and landing sites, called vertiports, are likely to experience intermittent closures due to, e.g., adverse weather. To ensure safety, all in-flight Urban Air Vehicles (UAVs) in a UAM network must therefore have alternative landing sites with sufficient landing capacity in the event of a vertiport closure. In this paper, we study the problem of safety verification of UAM schedules in the face of vertiport closures. We first provide necessary and sufficient conditions for a given UAM schedule to be safe in the sense that, if a vertiport closure occurs, then all UAVs will be able to safely land at a backup landing site. Next, we convert these conditions to an efficient algorithm for verifying safety of a UAM schedule via a linear program by using properties of totally unimodular matrices. Our algorithm allows for uncertain travel time between UAM vertiports and scales quadratically with the number of scheduled UAVs. We demonstrate our algorithm on a UAM network with up to 1,000 UAVs.