1. ¹Technion—Israel Institute of Technology, Haifa, Israel
2. ²Air Force Research Labs, Wright-Patterson AFB, OH, USA

Correspondence: T Shima, Department of Aerospace Engineering, Technion—Israel Institute of Technology, Haifa 32000, Israel. E-mail: tal.shima@technion.ac.il

Received November 2005; Accepted January 2008; Published online 9 July 2008.

Abstract

A problem of assigning multiple agents to simultaneously perform cooperative tasks on consecutive targets is posed as a new combinatorial optimization problem. The investigated scenario consists of multiple ground moving targets prosecuted by a team of unmanned aerial vehicles (UAVs). The team of agents is heterogeneous, with each UAV carrying designated sensors and all but one carry weapons as well. To successfully prosecute each target it needs to be simultaneously tracked by two UAVs and attacked by a third UAV carrying a weapon. Only for small-sized scenarios involving not more than a few vehicles and targets the problem can be solved in sufficient time using classical combinatorial optimization methods. For larger-sized scenarios the problem cannot be solved in sufficient time using these methods due to timing constraints on the simultaneous tasks and the coupling between task assignment and path planning for each UAV. A genetic algorithm (GA) is proposed for efficiently searching the space of feasible solutions. A matrix representation of the chromosomes simplifies the encoding process and the application of the genetic operators. To further simplify the encoding, the chromosome is composed of sets of multiple genes, each corresponding to the entire set of simultaneous assignments on each target. Simulation results show the viability of the proposed assignment algorithm for different sized scenarios. The sensitivity of the performance to variations in the GA tuning parameters is also investigated.