Page 25 - Build Your Own Quadcopter_ Power Up Your Designs with the Parallax Elev-8

4 Bu il d Y o ur O w n Q u a d c o p t e r

A Matter of Definition

There are a variety of descriptors associated with quadcopters that I would like to briefly
examine. Probably the most general description of a quadcopter is an unmanned aerial vehicle
(UAV). UAV has also been interpreted as an uninhabited aerial vehicle, which is precisely the
same meaning as unmanned aerial vehicle. Two descriptions that are more specific would
be those of remotely operated aircraft (ROA) and remotely piloted vehicle (RPV). The last two
descriptions mean that no pilot is physically carried by the aerial vehicle and all vehicle
control is accomplished either by a pilot using a remote ground station or autonomously by
the vehicle. A related definition for this type of operation is autonomous aerial vehicle (AAV).
It is often used to describe a UAV that is controlling its own operation, independent of any
ground station. However, it should be pointed out that all AAVs should have some kind of
autonomous override command available from a ground station, just in case something goes
wrong with the onboard flight-control system. Having a fail-safe mode should always be a
paramount design decision in any AAV project.
UAV, ROA, and RPV are the most popular and well-known descriptions for the quadcopter
type of vehicle. There is also one other popular descriptor: micro aerial vehicle (MAV), which
refers to any very small-sized UAV with all length, width, or height dimensions of 15 cm or
less. MAVs are actively being developed along with swarming control techniques in a variety
of research projects. Developers of some of these projects hope to implement insect biomimicry
into their MAVs in an attempt to achieve the performance and capabilities of their real-world
counterparts.
How Are Quadcopters Used?

The answer to the question of how quadcopters are used depends on whether one is viewing
them from a military or a civilian perspective. Military use of quadcopters lies mainly in the
intelligence, surveillance, and reconnaissance (ISR) field, and to a lesser extent, in tactical
deployments. Quadcopters are excellent ISR assets that nicely complement fixed-wing UAVs
that are extensively employed by many worldwide military organizations. Currently all
tactical deployments where weapons-carrying UAVs are deployed in actual combat are still
the domain of fixed wing UAVs, such as the U.S. Air Force MQ-9 Reaper, which is shown in
Figure 1.5.
The quadcopter, as of this writing, still cannot carry a heavy payload, such as a missile
or cannon, although it is likely that there are ongoing military research projects attempting
to overcome this limitation. There would be an obvious tactical advantage for a combat
unit to be able to deploy a small, airborne weapons platform that could hover over a
battlefield and engage enemy targets upon command. The old military adage of “gain the
high ground for tactical advantage” would definitely take on a new meaning with the use of
a tactical quadcopter.
Civilian uses for quadcopters are far more numerous than military ones at this time.
Some of these are listed in Table 1.1.
There are some legal restrictions in the United States regarding the civilian use of
quadcopter UAVs, including the FAA requirements that they not be flown any more than
400 feet above ground level and not near any airport. I am sure that similar restrictions are
in place in other countries, so I would urge you to research the laws and regulations that
are applicable in your country.
U.S. residents should also be aware that the airspace above their domiciles is not
exclusive for their use. In the 1946 decision, United States v. Causby 328 US 256 1946, the U.S.
Supreme Court held that only the landowner’s airspace that may be reasonably occupied or