UAV Path Planning in Search and Rescue Operations

Abstract

Unmanned aerial vehicle (UAV) search operations usually involve two consequent steps. The first one is the area of interest observation and data capturing with the aid of optoelectronic cameras, and the second one is the data transmission to the flight control center. Very often the position of the observed object is rather far from the area covered by a communication network formed by stationary general use base stations or a group of mobile base stations temporarily deployed for the search mission. This, as well as the constraints caused by surface features, may prevent the immediate transmission of the collected data. Therefore, after capturing the data, the UAV must find an appropriate position to perform a successful transfer of the information flow. Moreover, in case of manifold search mission, the UAV must be ready for an unplanned task correction, and therefore a landing and commencing a new flight are not acceptable. In this paper, UAV search mission planning is considered as a path optimization problem. The optimization goal is to set up the best conditions for data capturing and transmission under velocity and timing mission constraints. The optimization parameters are the UAV path and the data transmission plan; thus, the optimization problem is naturally decomposed into the internal problem of data transmission optimization and the external surveillance path planning. The first one is solved in an explicit way for a given path, and for the second one, the numerical solution in the deterministic case is found with the aid of the maximum principle. For the stochastic case, the approach is also outlined. The findings are illustrated by simulation results.