UAS Missions

6.4 Research:  UAS Mission

What are the design and implementation of a specific UAS mission (military, or civil)? Determine a specific subject mission, consider public use or emergency services as law enforcement, medical, rescue or fire related mission sets. In your response:

·         Identify and discuss the particular mission you are highlighting for a UAS

·         Select three platforms capable of performing the mission and obtain an appropriate reference citation for each

·         Discuss any considerations relative to the mission and if they correlate to the performance of any related mission execution tasks

·         Identify the benefits and challenges associated with performing the particular UAS mission you are highlighting

·         Identify and discuss at least two legal and or ethical challenges to the specific mission you are highlighting

There are many current missions and missions yet to be thought up that will be done by commercial UAS.  The variety of mission scope is large and continues to grow by the day as current and new companies innovate and emerge with new ideas.  One mission that will be highlighted here is the gathering of aerial data for surveying and Photogrammetry.  Photogrammetry is the science of making measurements from photographs.  The photographs are taken with a high degree of overlap and then a computing software processes the images together by finding matches from each photograph to stitch together an orthomosaic photograph.  The photos can be used to create point cloud models which can be used to make a digital surface models (DSM).  Point cloud models are transferred to CAD software through surface reconstruction.  The models can then be used to run simulations and predict behavior of the surface under various conditions and disturbances (such as flood, earthquakes, etc).  Traditionally this has been done by manned aircraft, but increasingly UAS are showing up to do the task for less the cost, especially for small areas. 

Limitation to UAS in performing survey tasks include both technical and regulation obstacles.  Many survey areas are multiple square miles in area.  To perform the survey efficiently, the UAS has to be able to fly beyond of line of sight (BLOS) miles away from the operator.  Sensor payload and altitude go hand in hand.  The higher the altitude the UAS is flown at, the quicker and more efficient the survey can be.  But at higher altitudes, sensors are required to be increasingly more accurate.  More accurate sensors will increase the cost.  Range, sensor accuracy, and altitude are all technical obstacles that obviously can be overcome by throwing more money at the project.  However, the UAS does not have an advantage over manned aircraft unless it is significantly less expensive.  So, the challenge is to design an aircraft with the range, sensor payload, and altitude capability in a low cost manner. 

Regulations present challenges to UAS surveying.  The currently proposed UAS rules only allow operation up to 500 ft AGL and prohibit BLOS operation.  For surveying of large projects, both of these capabilities are necessities.  The regulations should be modified to safely allow BLOS operation.  UAS outfitted with sophisticated sense and avoid systems and ADS-B equipment should be allowed to operate above 500 ft AGL and BLOS. 

Honeycomb Corp. AgDrone^TM System

Like most drone manufacturers, Honeycomb Corp is a relatively new company.  It was founded in 2012 and is based in Wilsonville, OR.  They have essentially one product, the AgDrone^TM System.  It is a fixed wing aircraft weighing a little under 5 lb.  It seems very capable, it includes dual 16.1 MP RGB visible and NDVI (Normalized Difference Vegetation Index) NIR (near infrared) cameras and ground resolution up 1.26 in with a flight time of 30-60 min, depending on wind and other conditions.  Both cameras can be carried on the drone during the same flight, no need to swap them out for different missions.  It is also constructed of durable aramid (Kevlar) composite.  It appears to be of more durable construction than the foam construction of the Sensefly eBee models.  One downside is the size, the wing span is just over 4 ft. It also appears that the drone is not collapsible for transport.  So with carry case and all, this is not a drone that you could just stuff in a backpack.  The cost for this drone appears to be in the mid range for survey / agriculture drones, $10 – $20 k.

3D Robotics

3D Robotics is a US company that has been around for a few years.  They started as a company providing resources and parts for the DIY (do it yourself) drone builders.  They have recently released the 3DR Solo, which is a direct competitor to the DJI Phantom series drones.  The Solo is built for the GoPro, but on a cost basis it is about $400-$500 more than the Phantom 3 for a similar setup.  The Solo will not be further described here for this reason. 

The only other 3DR model of merit to mention is the Aero-M.  The Aero-M is a revamped Aero, built specifically for mapping.  The Aero came out a few years ago and is a fixed wing drone, costing around $1300 and does not come with a camera (though some DIY people have reported success with retrofitting the Sony S100 and others).  The Aero-M and the X-8 (3DR’s quadcopter mapper) both come in at a price of $5400.  The Aero-M comes with a 12 MP camera mounted looking down and has automated software for creating, flying, and analyzing mapping missions.  The software is downloaded to any laptop computer.  It allows a polygon to be selected on a map for the desired survey area.  The software then calculates the waypoint grid, altitude, flight time, and ground sampling distance that can be achieved.  The waypoints are then uploaded from the laptop to the aircraft.  Once uploaded, the aircraft is pre-flight checked and armed and then it is simply thrown into the air.  The aircraft senses the forward movement and it automatically starts the prop and then flies the mission.  When the mission is complete, the aircraft will automatically land in the designated spot.  FPV kit with nose mounted camera is included.  A separate receiver and monitor is required to view the video feed.  The aircraft does not appear to be very rain resistant.  Flight time is about 40 minutes and the range is about 1 km (0.62 mi).  Ground sampling distance is 2 in/pixel.  The weight is 6.8 lb. 

The aircraft can be flown automatically or manually.  It comes with a scaled down version of Pix4D (made by a Swiss company and one of the current standards today for mapping software).  This version of Pix4D allows only 2D mosaics and does not support 3D images.  The Pix4D 3DR version is specific to the Aero-M and the X-8-M.  The X-8-M is 3DR’s quadcopter mapper and will not be discussed further because similar tasks can be done with the DJI Phantom series for much less the cost.  The Aero-M must have a wide open space to takeoff and land.  The aircraft is landed by performing a belly landing.  Depending on the surface the belly landing has the potential to cause damage to the aircraft and to the camera sensor.  The aircraft appears to be constructed of foam that may dent and crack easily. 

For the price, the 3DR Aero-M appears to be the most affordable entry point into professional fixed wing mapping drones.  The price cannot be beat for the capability that it offers.   

Aeromao

                Aeromao is a Canadian company that seems to have very capable fixed wing aircraft for mapping priced in the mid-commercial range ($8-$16k).  The Talon is the lowest price option.  The 300 and EV2 are the other higher priced, higher performance options.  The Talon comes with the Sony a5100 24 MP camera with a survey grade lens and boasts a 20 km (12 mi) range!  Endurance is 80 min!  Ground Sampling Distance (GSD) can be as good as 1.5 cm/pix (0.59 in/pix)!  The camera has a lens protector that automatically uncovers the camera after takeoff and covers the camera before landing to protect the camera.  It also comes with a parachute landing system so that the aircraft can be operated in rugged environments.  Options for dual sensor operation and a wide variety of hot-swappable sensors (NIR, FLIR, etc) are available.  The Talon has all electronics enclosed and is able to fly in light rain.  With these features and a price of around $9000, this is a pretty awesome package in comparison to other COTS UAS currently available. 

However, as an entry point, the 12 mi range, 80 min endurance, and 0.59 in/pix resolution may be a little overkill.  It sure does put the Sensefly eBee and the Honeycomb Agdrone to shame though, because both of those UAS are priced above the Talon.  This is a serious UAS that would be useful for very large surveys in remote areas, such as for forest service use.  The Talon is after all made by a Canadian company.  With Canada’s wide expanse of remote territory it is understandable that this UAS would be very useful in such an environment.  For surveying one Farmer’s field, this is probably a little too much.     

References

American Society for Photogrammetry and Remote Sensing. (2015, June 10). Retrieved from Wikipedia: https://en.wikipedia.org/wiki/American_Society_for_Photogrammetry_and_Remote_Sensing

Austin, R. (2010). Unmanned Aircraft Systems. West Sussex UK: John Wiley & Sons.

Geographic Information System. (2015, June 27). Retrieved from Wikipedia: https://en.wikipedia.org/wiki/Geographic_information_system

Photogrammetry. (2015, June 25). Retrieved from Wikipedia: http://www.geo-matching.com/category/id64-uas-for-mapping-and-3d-modelling.html?param=ZmlsdGVyWzQ2NDY5XVtdPUFpcmNyYWZ0&sort=br

Point Cloud. (2015, May 19). Retrieved from Wikipedia: https://en.wikipedia.org/wiki/Point_cloud

UAS for Mapping and 3D Modeling. (2015). Retrieved from Geo Matching.com: http://www.geo-matching.com/category/id64-uas-for-mapping-and-3d-modelling.html?param=ZmlsdGVyWzQ2NDY5XVtdPUFpcmNyYWZ0&sort=br

 

 

Module 4.4
How can the separation of unmanned aircraft be monitored and maintained (among other unmanned aircraft and manned aircraft) in the National Airspace System (NAS)? What considerations need to be made for varying sizes (i.e., Group 1 to 5) and airframes of UAS (e.g., fixed-wing, rotary-wing, and lighter than air)? What technology is currently employed by manned aircraft and is it adaptable for use with unmanned?

In general, upcoming regulations for UAS should be constructed by taking into account the size, weight, and mission of the UAS being used.  The regulations should not be overly burdensome on the nascent UAS commercial industry while meeting the intent of safety regulations.  To some extent it makes sense for small UAS operated within line of sight to be self-separated by the operators.  This means that each small UAS operator would be responsible for overseeing the flight of the UAS and for avoiding obstacles as well as other UAS and manned aircraft.  Granted some training would be required so that the operator can understand how far they must operate from objects, UAS, other manned aircraft.

In the past, self-separation of aircraft has been done by the pilot ensuring that they stay “well clear” of other aircraft.  When an automated system needs to provide self-separation, and ambiguous term such as “well clear” is not helpful.  Weibel’s work shows a probabilistic approach using a predefined risk threshold to define the boundary of “well clear” numerically so it can be acted upon by an automated system. 

Well clear performance would be assessed through safety assessment, as part of an overall target level of safety analysis for midair collision. An unambiguous boundary provides a clear measure of when execution of well clear separation has failed.

An analytical definition of well clear, such as the one proposed above would be implemented in a UAS collision avoidance system as a desired avoidance boundary. Avoidance actions would be designed to be executed by automated systems or a human in the loop who would seek to maintain well clear through horizontal or vertical maneuvers.

The horizontal contours of 5% collision risk suggest that a well clear boundary based on this threshold would extend approximately 8,000 ft ahead of an aircraft, 3,000 ft. laterally, and 3,000 ft behind.

By framing the threshold as a separation standard, boundaries can be derived based on an acceptable threshold of risk that is incurred from violating the threshold. This has the additional advantage of being comparable to the expected decision-making of pilots in executing self-separation. In the discussion below, a potential well clear boundary is proposed, and additional considerations and future work are outlined (Weibel, 2011).

Automated self-separation will occur most likely with a UAS that is operated out of line of sight range of the operator.  Video cameras may not be sufficient for the operator to provide self-separation of the UAS.  In this case automated systems operated by cell tower signals may be appropriate.  The automated system would need to actively “sense and avoid”. 

ADS-B (Automatic Dependent Surveillance Broadcast) is one way that UAS could provide their location to other UAS, manned aircraft, and ATC.  ADS-B is already being rolled out and will be required by all manned aircraft by 2020.  Smaller ADS-B systems are being developed that could be carried on a UAS.  By using this technology UAS could broadcast their location, while seeing others’ location.  Traffic Information System technology could be used to alert the UAS operator to nearby aircraft.

 

 

 

References

Weibel, R. E. (2011). Establishing a Risk-Based Separation Standard for Unmanned Aircraft Self Separation. Ninth USA/Europe Air Traffic Management Research & Developement Seminar, (pp. 14-17). Berlin. Retrieved from http://www.atmseminar.org/seminarContent/seminar9/papers/64-Weibel-Final-Paper-4-12-11.pdf

The Quadcopter, Then and Now

The quadcopter was actually an early design for vertical lift.  The design showed promise because the short rotors were easy to manufacture, the counter rotating sets of blades cancel the torque so the craft does not spin in a circle, mechanical linkages aren’t needed to vary rotor pitch, and the load is less per rotor since there are 4 instead of just one.  Also, as opposed to the single rotor copter, the quadcopter balances torque by using motors that are creating lift.  In a single rotor copter, there is waste in having a tail rotor that doesn’t create lift or thrust.  Other factors that lead to a prominent single rotor design was that a payload naturally hangs below a single rotor in a stable manner and there could be one engine, tied to only one rotor (reduced complexity).  The disadvantages of the early quadcopters were the heavy weight associated with 4 propulsion systems and the overwhelming workload on the pilot to independently control 4 rotors simultaneously.  Early flying designs included the Oemichen No2 (1920), De Bothezat (1923), Covertawings (1956), Curtis Wright VZ-7 (1958)

Figure 1: Oemichen No. 2, 1922 [12]

Figure 4:Curtiss-Wright VZ-7, 1958 [9]

Probably the significant recent developments that are allowing quadcopters to make a comeback and be viable in the UAV field is the material weight reduction and computing power.  Advances in material science allow for very strong, but very lightweight materials to be manufactured.  Lighter weight puts less strain on the rotors.  High power density lightweight motors enable very small and inexpensive, but powerful motors to be used.  Also, the drastic improvement in computing power enables miniature flight controllers and electronic speed controllers that automatically adjust the speed of each of the 4 rotors to keep the torque balanced, ascend and descend, forward/backward/side to side movement, and balancing for disturbances such as drift and wind currents.  Everything is handled by the computing system so that the pilot does minimal compensation/correction control and can focus on flying where he wants to go.  Quadcopters and other multi-rotors will increasingly become prevalent for Unmanned applications because of their mechanical simplicity and ease of control.  For safety reasons, I think that a manned quadcopter may not happen.  If a conventional single rotor helicopter looses its engine, the helicopter can perform an autorotation landing and have a chance of the pilot surviving.  With a quadcopter, if one rotor/motor is lost then the craft will be unstable and crash.

 

References

History of Quadcopters and Other Multi-Rotors. (n.d.). Retrieved from Krossblade Aerospace: http://www.krossblade.com/history-of-quadcopters-and-multirotors/

Ottaviano, N. (n.d.). History. Retrieved from Quadrotor Drone: https://sites.google.com/site/quadrotordrone/home/history

What Makes the Quadcopter Design so Great for Small Drones? (n.d.). Retrieved from Forbes: http://www.forbes.com/sites/quora/2013/12/23/what-makes-the-quadcopter-design-so-great-for-small-drones/