I. Introduction
The unmanned aerial vehicles (UAV) or drones are aircrafts which do not require a human pilot on board but are remotely piloted or self-piloted and can carry various pieces of equipment such as cameras, sensors, communications equipment, weapons. Compared with the general planes, they have the advantage of low-cost, high-security, high survival ability, good maneuvering performance. The path planning for the UAV is one of the most important problems and it presents a large-scale multi-constrained optimization problem. The UAV path planning requires calculation of the sub-optimal route between the initial location and the desired destination with avoidance of the hazardous areas, fuel consumption minimization and consideration of other constraint conditions.