String stable platoons of all-electric aircraft with operating costs and airspace complexity trade-off

TL;DR

This paper develops an optimal control framework for all-electric aircraft platoons that balances operational costs and airspace complexity, ensuring string stability and safe separations in urban air mobility scenarios.

Contribution

It introduces a novel pairwise dynamic workload function and derives both optimal and suboptimal airspeed solutions with formal stability conditions for heterogeneous aircraft platoons.

Findings

Suboptimal solution closely matches the optimal in performance.

Method reduces operational costs and airspace complexity.

Ensures string stability and safe separations in simulations.

Abstract

This paper formulates an optimal control framework for computing cruise airspeeds in predecessor-follower platoons of all-electric aircraft that balance operational cost and airspace complexity. To quantify controller workload and coordination effort, a novel pairwise dynamic workload (PDW) function is developed. Within this framework, the optimal airspeed solution is derived for all-electric aircraft under longitudinal wind disturbances. Moreover, an analytical suboptimal solution for heterogeneous platoons with nonlinear aircraft dynamics is determined, for which a general sufficient condition for string stability is formally established. The methodology is validated through case studies of all-electric aircraft operating in air corridors that are suitable for low-altitude advanced/urban air mobility (AAM/UAM) applications. Results show that the suboptimal solution closely approximates the optimal, while ensuring safe separations, maintaining string stability, and reducing operational cost and airspace complexity. These findings support the development of sustainable and more autonomous air traffic procedures that will enable the implementation of emerging air transportation technologies, such as AAM/UAM, and their integration to the air traffic system environment.