Impact of Uncertainty on Collision Avoidance between Multirotor Small Unmanned Aircraft System and Manned Helicopter in Multilateration Environment

Abstract

Recently, with the increase in the number of small unmanned aircraft system (sUAS) flights, the risk of collisions between sUAS and manned aircraft such as helicopters flying at relatively low altitudes is also increasing. For mitigating the risk, we develop a collision avoidance method for multirotor sUAS, assuming the encounter with a manned helicopter in a multilateration (MLAT) environment, which is a surveillance system for manned aircraft. The MLAT system can also detect manned helicopter's position but has position error. The proposed collision avoidance method is formulated based on Markov decision process considering uncertainty from the position detection error in the MLAT environment. The optimal action for avoiding collision is derived by solving the formulated collision avoidance problem using dynamic programming. Numerical simulations are held for evaluating the impacts of uncertainty on the collision avoidance method. The results show that the proposed method can avoid the collision between sUAS and manned helicopter while considering uncertainty from the MLAT environment. Additionally, the proposed method is evaluated based on the collision risk ratio, and the evaluation results show the requirements for the MLAT performance for realizing safe collision avoidance.