During my years of designing software, especially during the development of image recognition systems, there was often an emphasis on military applications. The recent rise of the machines using various drones and other remote sensor robotics has reminded me of that time of my life.
The recent gun control argument in the US has brought to the forefront a great discussion on the merits or demerits of owning and carrying weapons. Most of the time the military use of weapons is restricted to wars or training, however the advent of terrorism has become the issue for those weapons, especially in its use of modern technology.
The AK47 is a rather formidable machine gun, able to survive rough treatment and neglect and then be used reliably in battle. Various other military machine guns are used for other purposes, although most of them are very expensive. The AK47 is cheap and used by most of US enemies.
One detectable feature common to nearly all such guns is the use of steel. Barrels and firing mechanisms especially must be strong and resistant to damage during the rough conditions of battle. Plastic grips or even magazines and belts might be OK, lightening the weapons somewhat, but steel is the primary weight of those kinds of devices.
Imagine a 1 meter sphere plunging to the Earth, with the balance of weight near the bottom, with a last few seconds deceleration by parachute just before hitting the ground. Once touching, the parachute is ignited and burns completely away, so that nothing entangles the device. A spike preceded the ball and pierced deep into the ground, solidly anchoring the sphere which then unfolds like flower petals to expose a small machine gun fitted with a motor and computer vision enabled telescopic sight.
Instantly, within a second or so of anchoring, the device begins to rotate so that the firing end of the gun is pointed outward toward the area that the camera can view, in a full 360 degrees. The computer watches the camera images and detects multiple frequencies, including microwave, visible and infra-red. The first rotation of the device takes about a second, after which all points detected by the camera and determined to be steel and shaped like weapons are selected as targets.
The next rotation involves firing upon all selected targets. Once the magazine of the device is empty, or all targets have been eliminated, firing stops. After a siren begins to wail, which is intended to warn off nearby "non-targets", a timer will count down until after perhaps 1 minute or less, the device will explode like a land mind.
The explosion is not primarily for lethality, only to prohibit such devices from being captured, at least in large numbers. The electronics and camera devices of the machine will be utterly destroyed, leaving only the metal parts of the gun behind, although mangled. Therefore, once their mission has been accomplished, they erase themselves.
Obviously the possibility of friendly fire and mistaken metal non-weapons in the hands of innocents would be a problem. Therefore the recognition software employed by the device would be parametrized to detect ONLY military weapons which will be shaped in certain ways, reflect microwaves in certain ways or whatever.
In such a future combat, holding a weapon would be a liability. What would then most likely result would be a somewhat evolved enemy who would learn from the experiences and employ weapons in a different, more difficult to detect manner. Wrapping all weapons in tin-foil, wearing wire mesh garments, and other shielding mechanisms might work for a while, however such diversions would be short-lived, since the devices would also be capable of bidirectional communication using light or whatever band is the least noisy. All events would be recorded, much like gun-camera recordings in UAVs or piloted planes.
Anyone caught wearing wire mesh, using tin foil or whatever would merely be targeted as secondary targets, in the case that primary targets were unavailable. Unarmed or non-metallic objects would be completely free from selection, however there might always be the chance of deflected bullets or shrapnel injuring people unintentionally.
The scenario I have described is only a single instance of robotics. There are many other weapons used by terrorists or enemy combatants that fall outside these parameters. However those kinds of weapons are usually suited to larger offensive weapons platforms, i.e. artillery, missiles and bombs. Others are only able to be confronted up close and personal.
None of the above designs were actually developed, to my knowledge. There were only discussions of all possible countermeasures and side effects. I don't personally want to be responsible for any deaths for any reasons outside self-defence.
Yet I find it ironic that people want to wear guns when those very devices make them stand out as targets to the increasingly more sophisticated robotic systems that are proliferating in our world.