The use of Drones is becoming more and more popular across various industries and military due to the fact that they can be outfitted with various pieces of equipment to accomplish a predetermined task or mission whether it be surveillance or fighting terrorist over seas. One company in Taiwan has found a way to weaponize quad-copters with rifles and grenade launchers.
I found this in a Facebook group. It seems that the Taiwan 205th Armory (the same people who make the T91 rifle) is experimenting with arming drones. The T91 drone is equipped with a T91 rifle while the other is a 40mm armed drone with three grenade launchers.
We have seen armed drones before (e.g. Iraqi soldiers have been arming their drones with grenades even attaching shuttlecocks to grenades to help stabilize them as they fall). While it is a little lower tech, dropping grenades seems like a much easier solution than launching 40mm grenades or shooting a T91.