Real-time optimal mission scheduling and flight path selection

We consider a mission in which m UAVs with a capacity limit q each visit n( <= mq) targets in a hostile environment in a cooperative manner (and return to where they departed from) such that the cost reflecting operating time and risk exposed is minimized. We first propose a mixed-integer linear programming (MILP) formulation which exactly solves the problem and then propose four alternative MILP formulations which are computationally less intensive and, therefore, suited for real-time purposes, but yield a theoretically guaranteed suboptimal solution. The main contributions of this note are an exact but compact MILP formulation, using a room concept, and four nonexact formulations, each one of which ensures a certain level of solution quality and relatively fast computational time for the considered real-time mission scheduling problem.