Module 7.4 – UNSY 605
In
order for unmanned systems to become a more viable option for many
applications, the sense and avoid technology they operate must improve
significantly. The currently available
options for unmanned systems do not provide effective enough detection and
response capabilities to be viable options.
As a result, unmanned aerial vehicles (UAVs) present a severe risk for
mid-air collisions with other aircrafts or stationary objects such as buildings.
Due to the risk of collision associated
with flying UAVs, they must be flown within line of sight, which restricts their
use for many applications at this time (Roden 2016). The development of sense and avoid technology
is advancing in two stages: improved
sense and avoid technology for better information relay to an operator and the
development of completely autonomous sense and avoid technology (Roden 2016). Both of these stages of development face
major challenges, but there are some sensors available for operator-controlled UAVs.
One popular avenue of improving sense and avoid sensor
for UAVs has been to incorporate information from Automatic Dependent
Surveillance-Broadcast (ADS-B) transponders.
There are two parts to an ADS-B, the ADS-B In and the ADS-B Out
(Cincinnati Avionics 2016). The ADS-B Out
uses onboard GPS to transmit its position information to Air Traffic Control
(ATC) while the ADS-B In receives position information on other aircraft
carrying an ADS-B transponder (Cincinnati Avionics 2016). uAvionix has designed several versions of
their ADS-B transponders for commercial usage and the ping2020 ADS-B
transceiver is perfect for use on small UAVs.
The ping2020 weighs only 20 grams and has a minimal power requirement at
500 mW (uAvionix 2016). Aside from its
small size, the ping2020 is optimal because it accomplishes both the ADS-B In
and ADS-B Out functions (uAvionix 2016).
The ping2020 can detect objects within a 100 mile radius on two ADS-B In
frequencies, 1090 MHz and 978 MHz (uAvionix 2016). As for the ADS-B Out, the ping2020 transmits
on the 978 MHz frequency (uAvionix 2016).
The only detail about the ping2020 is not ideal is the price. Though I could not find a valid source for
the price, I found one listing of the ping2020 for $1200, which is higher than
desired when it comes to such a small component.
The ping2020 is a solid starting point for the first
stage of sense and avoid technology development, but it is by no means a final
solution. The idea behind implementing
an ADS-B transponder into a sense and avoid sensor is helpful, but it has its
major faults. The main issue is that in
order to sense another aircraft that aircraft also has to be equipped with an
ADS-B transponder. The Federal Aviation
Association (FAA) recently mandated that operate in U.S. National Airspace must
be equipped with ADS-B by the year 2020, which means that the number of
aircraft which are detectable by the ping2020 will be much higher (uAvionix
2016). However, the ADS-B makes no
improvements on the sense and avoid capabilities of stationary objects such as
buildings or trees. More than likely,
small UAVs will not be operating in a high altitude environment for extended
periods of time, which means that they will have to navigate obstacles
presented by lower altitude areas.
The bottom line for commercial small UAV operations in
the future is that the discrimination capabilities of sense and avoid sensors
must improve drastically. Adding
additional components, such as the ping2020 ADS-B, can help patch some of the
issues for a short time. But in the end,
the sense and avoid sensors themselves have to become more effective to move
forward in both operator-controller and autonomous UAV operations.
References
Cincinnati
Avionics. (2016). ADS-B 101: what you need to know. Retrieved from http://cincinnatiavionics.com/ads-b-101-what-you-need-to-know/
Roden,
M. (2016). SkyTech Event: UAV Conference & Exhibition. Retrieved
from http://www.skytechevent.com/#!Sense-and-Avoid-The-Technology-to-Watch/c1leh/559bb52c0cf2361ae7868374
uAvionix. (2016). PING-2020 ADS-B Transceiver. Retrieved from http://www.uavionix.com/products/ping2020/