Mini and micro versions of UAVs were introduced in 1990, and, the famous Predator drone was introduced in 2000. This was used in Afghanistan to launch missiles and in the search of Osama Bin Laden.
Each drone in a swarm is propelled by a specific number of rotors and has the ability to vertically hover, take-off, and land (VTOL). The flight of the drones is controlled either manually, i.e. by remote control operations, or autonomously by using processors deployed on the drones [1].
