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/