Sense and Avoid Sensor Selection - UAS under 55lbs

     The inevitable integration of Unmanned Aircraft Systems (UAS) within existing airspace
has to be carefully controlled to ensure the safety and efficiency of not only the National
Airspace System (NAS) but the world’s airspace is not degraded.  Aircraft collision avoidance
can be separated into two categories, cooperative aircraft and non-cooperative aircraft.  The
technology to separate aircraft operating in these two categories is readily available; however,
the biggest problem is integrating this technology into a relatively new system so it can
satisfactorily perform its function.  There are a number of products on the market that claim to be
the best option for Sense and Avoid (SAA) technology which include: Traffic Collision
Avoidance System (TCAS), Automatic Dependent Surveillance-Broadcast (ADS-B), Electro-
Optical (EO) cameras, Light Detection and Ranging (LiDAR), radar, and acoustic systems.  In a
perfect world any UAS, regardless of size, would/should integrate all available technology to
ensure airspace integrity; however, this is currently not possible with UAS under 55 pounds.  In
order to detect and avoid cooperative, non-cooperative aircraft and wildlife, the combination of
these two SAA systems will be the best option for small UAS: Sagetech’s ADS-B transponder
and SARA’s Passive Acoustic Non-cooperative Collision-Alert System (PANCAS).

     The biggest challenge with smaller UAVs is getting the SAA sensory package small
enough to fit alongside numerous other electronics and still permit UAV maneuverability. 
Sagetech Corporation has solved that problem with their revolutionary transponder.  It is the
smallest transponder in the world and is easily the choice for UAS where size, weight and power
are needed for efficient operations (SAGETECHCORP, 2015).  Sagetech Transponders measure
just 3.5” x 1.8” x 0.7” and weigh only 100 grams.  Compliant up to 60,000 feet; the flight
computer can read altitude data from the transponder providing backup altitude information.

Supply Voltage is 10-32V and power consumption is 8 watts (typical) 14 watts (max).  The
company offers three variations to their transponder (SAGETECHCORP, 2015):

• Mode C Transponder – Small, high reliability solution for Mode A and Mode C requirements (Mark XA AIMS certified version is also available)
• Mode S Transponder with ADS-B Out – Enhance your safety of flight, thanks to increased visibility afforded by NextGen's ADS-B
• Mode S Transponder with ADS-B Out and GPS – Include your GPS location in Mode S communications

Even though this tiny transponder will revolutionize the UAS industry in the next 5-10 years, it
will not be very beneficial at the present time.  Until all aircraft are equipped with ADS-B
transponders and receivers, UAV SAA systems must rely on other equipment to identify other
aircraft and take evasive maneuvers.

     Solving the problem with detection and avoidance of obstacles in today’s airspace is
SARA’s PANCAS.  PANCAS enables UAVs to meet FAA standards for detecting and tracking
aircraft.  The PANCAS uses an array of four lightweight acoustic probes and a custom-designed
digital-signal processor (SARA, 2012).  Eliminating the worry of an unbalanced or less then
airworthy UAS, the PANCAS uses windscreen technology and mounting hardware that eliminate
the effect of wind noise and aircraft vibration (SARA, 2012).  The digital-signal processing
board filters the acoustics, detects, tracks targets and produces an avoidance command that eliminates an imminent collision; simultaneously sending the respective data to the ground
control station via data downlink for operator awareness.  The total weight of the sensory
package is 250g and uses around 7 watts of 6-volt DC power.  An advantage with using an
acoustic sensory suite over other optical or radar based alert systems is:

• Offers all-weather collision avoidance capabilities
• PANCAS can be integrated into and Class UAV hardware
• Provides 360 degree (spherical) coverage
• Ability to detect objects day or night, through clouds or fog

     In summary, the combination of the Sagetech’s ADS-B transponder and SARA’s
PANCAS will allow small UAS to operate safely and efficiently within the NAS and airspace
around the world.

- Garrick


References

SAGETECHCORP.com, (2015). XP Family Of Transponders.  Retrieved from
http://www.sagetechcorp.com/unmanned-solutions/
SARA.com (2012). UAV Acoustic Collision-Alert System.  Retrieved from
http://www.sara.com/ISR/UAV_payloads/PANCAS.html

CONTROL STATION ANALYSIS

     A challenge has presented itself to identify a Ground Control Station (GCS) that can be
either used by ground or maritime systems and breakdown its functionality (good, bad, ugly).  I
can take the easy route and pick the first thing my preferred internet search engine display;
however, I wanted to present something a tad-bit outside the box.  More times than not, when
someone pictures an Unmanned System (US) GCS a large room comes to mind equipped with a
huge array of advanced electronics.   This image holds true to some of the military’s current
control stations or even the National Oceanic and Atmospheric Administration (NOAA) ground
control stations.  On the opposite side of the coin, GCS’s can be as simple as a control tablet/pad
or an Electronic Ordnance Disposal (EOD) control unit set-up in the back of a Mine-Resistant
Ambush Protected (MRAP).  I would like to present the middle ground if you will in control
stations. 

     Let me introduce UAV Factory’s off-the-shelf portable GCS.  This particular GCS offers
it users a flexible yet extremely powerful alternative to your current off-the-shelf unmanned
system controllers.  UAV factory has made this particular GCS customizable per customer
request to fit its users unmanned control system needs.  From a business perspective,
customization is a very important feature of this product due to the numerous unmanned vehicle
applications being used worldwide.  This GCS uses a distinctive Modular Electronic
Compartment (MEC) which houses the control stations electronics.  The MEC dimensions are
3.2ft X 1.3ft and are made from a damage resistant material.  The MEC allows the user to
quickly uninstall and install new hardware.  This flexibility enables users the ability to
control/monitor sensors of numerous unmanned vehicles or robotics with little downtime.  Per
manufactures website, here is a list of features (UAVFACTORY, unk):

•  Universal off-the-shelf ground control station 
•  Based on fully ruggedized Panasonic CF-31 Toughbook
•  Integrated Toughbook docking station
•  Two Hot-swappable lithium batteries
•  User-dedicated modular electronics compartment
•  Two 12 V power outputs for datalinks
•  Comprehensive set of connections
•  Super bright 17” and 13” touch screen displays
•  10-32 VDC input range
•  Intuitive power monitoring display
•  Over-voltage, overcurrent, reverse polarity protection
•  Battery over-discharge protection
•  User-serviceable fuses
•  Removable Cordura bag for accessories
•  Carry handles, wheels and shoulder strap for convenient transportation
•  Ruggedized and lightweight design

Let’s look at the systems data depiction and presentation strategy as offered by it array of user
electronics.

     Data depiction is presented to the user via Panasonic’s field proven CF-31 Toughbook as
well as the GCS’s additional 17’’ sunlight readable touch screen display (UAVFACTORY, unk). 
Connections are made through the following: -2 serial (RS-232), 5 USB, 2 Ethernet, 1
Composite Video in, 1 VGA in, 1 Microphone in, 1 Audio out, PCMCIA slot, and HDMI.  The
presentation strategy is clearly and simply displayed using the two available screens.  The respective Toughbook displays images using a 13.1” XGA 1200 nit touchscreen (Panasonic,
2013).  The 17’’ display is presented in 1280 x 1024 (SXGA) and has an optional touch screen.
The users unmanned vehicle operation(s) will be conducted using the Toughbook
Operating System (OS) system software.  Currently the Toughbook is using a Windows® 8.1
Pro 64-bit OS.  This current iteration of Windows is a powerful option that will efficiently utilize
and take advantage of the systems Intel® Core™ i5-5300U vPro™ Processor.  User interface is
conducted via touchpads, mouse, and touchscreens.

    I want to give you (the reader) some negative reviews (as most writers tend to do, as it’s
easy to criticize) of the GCS and point out its numerous flaws; however, I really can’t find any.  I
have yet to use this particular GCS, but after reading current user reviews and thoroughly going
over the system specs via its easy to understand 23 page manual, I find myself liking it more and
more.  The only challenge I can conjure up would be finding level ground to place the GCS stand
on.  Unlike identification of system flaws, I can recommend the following change: integrate a
cooling system (fans, etc) within the docking stations.  This would assist with keeping your
expensive electronics running a peak performance and eliminate unneeded damage cause by
overheating.



References

UAV Factory (unk). Unmanned Platforms and Subsystems.  Portable Ground Control Station. 
Retrieved from http://www.uavfactory.com/product/16

Panasonic (2013). Toughbook 31.  Retrieved from
http://www.business.panasonic.com/toughbook/fully-rugged-laptop-toughbook-31.html