Sensor Placement in Photography and Racing Drones

Sensor Placement in Photography and Racing Drones

Sensor placement is one of the most crucial elements of unmanned system design, and

the purpose of the unmanned system dictates exactly where and how critical sensors are 
placed.Quadcopter drones (the four-rotor helicopter drones that have become 
ubiquitous in electronics stores) all look similar from a distance, but vary wildly 
in their sensor placement depending on their purpose. Two such unmanned systems 
are photography drones and FPV racing drones, which superficially look similar 
but are actually worlds apart in both purpose and sensor placement.

           

DJI is one of the industry leaders in hobby and commercial photography drones, 
and their Phantom 4 drone stands at the top of their professional-level UAV 
catalog (Mellors, n.d.). According to Mellors (n.d.), the chief feature of the 
Phantom 4 is the 4K camera, which enables the user to record ultra-high 
resolution video. Below is an image of the drone:

This is a great example of the drone’s camera placement. It is mounted on a 
gimbal on the bottom of the craft, which gives it the ability to both rotate and 
pan up and down.  This allows the camera to adjust to a wide variety of 
positions while the drone is hovering in place, giving the pilot the ability 
to capture a wide variety of images and angles without having to reposition 
the drone. The gimbal also compensates for the UAV’s movement in the air, 
enabling the camera to record stable footage even if the craft is moving 
(Mellors, n.d.). Sensor placement is key in the DJI’s functionality as a
photography tool.

            

Camera drones aren’t the only quadcopters in the skies; first-person view (FPV)
racing drones are also becoming popular. FPV drone racing is a growing sport 
where competitors fly their drones through pre-built tracks (Drone Enthusiast, 2016). 
The “FPV” is the key term here; operators utilize displays which show a first-person 
view from the drone, almost as if the pilot is sitting in the drone’s cockpit. The 
FPV requirement dictates very specific mounting for the racing UAV’s camera, 
namely its nose:

This is the Walkera Rodeo 150 FPV racing drone. Just like the DJI Phantom 4, 
it is a quadcopter, but that is where the similarities end. The Rodeo is a lightweight 
craft; it only weighs a hundred and fifty grams, and is designed for indoor and 
outdoor racing (Brown, n.d.). According to Brown (n.d.), it is also designed for 
aerobatic flight.

            

Since this is an FPV racing drone, the camera is mounted to the UAV’s nose,
centered in such a way as to simulate a cockpit view. According to Brown (n.d.), 
the camera’s position is fixed in place, with the optics allowing for a wide-angle 
view of one hundred and ten degrees. As Brown (n.d.) points out, this is a suboptimal 
position for photography, which removes the drone from consideration for serious 
photographic work. However, in its intended use as an FPV viewfinder, the drone
works very well, with the UAV’s electronics transmitting the camera’s

data to a viewing device with almost no lag.

            

Sensor placement is a critical element of UAV design, and the drone’s purpose often

decides where key sensors are placed. The most important sensor on both a racing 
drone or a photography UAV is the camera, although camera placement varies wildly 
from one platform to another. The DJI Phantom 4 carries its camera on its belly in 
order to allow for maximum photographic flexibility; the Walkera Rodeo 150 carries 
its camera on its nose, in order to give its pilot the best possible view when careening 
through a racetrack at high speeds. Both drones work well in their intended roles, and 
sensor placement is key to their successful function.

                                                               References

Brown, J. Walkera Rodeo 150: a compact FPV quadcopter for racing. Retrieved from

    

     http://mydronelab.com/reviews/walkera-rodeo-150.html on 27 September 2018.

Drone Enthusiast (2016). FPV drone racing – the UAV sport about to hit the big time.
     
     Retrieved from https://www.dronethusiast.com/fpv-drone-racing/ on 

     27 September 2018.

Mellors, J. (n.d.). DJI Phantom 4 review for photographers. Retrieved from

     

     https://shotkit.com/dji-phantom-4-review-for-photographers/ on 27 September 2018.

           

           

                                                       US Navy Bluefin-12(D)

In November of 2017, an Argentinian Navy submarine named the ARA San Juan
disappeared while traveling from an Argentinian naval base in Tierra del Fuego to its home port
in Mar del Plata (McKirdy, 2017). According to McKirdy (2017), the submarine, if underwater,
was in danger of running out of oxygen in as little as seven days. The vessel’s disappearance
sparked a frantic search from both the Argentine Navy and its international partners.  One of
those partners, the US Navy, deployed four unmanned underwater vehicles (UUVs) in support of
the search (Werner, 2017). According to Werner (2017), one of those vehicles was the Bluefin-
12(D).

The Bluefin-12(D), manufactured by General Dynamics, is a torpedo-shaped, highly
modular UUV capable of diving to a maximum depth of fifteen hundred meters (General
Dynamics, n.d.). According to General Dynamics (n.d.), its primary prioproceptive sensor is an
inertial measurement unit (IMU), which internally monitors the UUV’s speed and pitch in the
water. General Dynamics (n.d.) also states that one of the craft’s chief exteroreceptors is a
doppler velocity log (DVL), which measures the doppler effect created by the UUV as it
travels through water and then uses that information to confirm the IMU’s data. Rounding out
the suite of navigation sensors are a GPS and a compass, all of which aid the Bluefin in
navigating deep water.

The US Navy made an official statement that the Bluefin-12(D) was being utilized in the
search, but did not specify what search and rescue-specific modifications were made to the craft
(US Navy, 2017). However, a quick look at the Navy’s official photo of the Bluefin shows that it
is missing one modification that I think would greatly improve the craft’s ability to carry out its
mission: a manipulator arm.

                                      Bluefin-12(D). Source: US Navy Public Affairs Office.

I believe that a manipulator arm would greatly increase the Bluefin’s effectiveness, as it
would give the craft the ability to move debris and remove obstacles, thereby clearing a path for
manned rescue efforts. While not specified in the craft’s spec sheet, the Bluefin’s modularity
indicates that it can be mounted with a manipulator arm without too much difficulty.

Unmanned aerial vehicles (UAVs) can be combined with unmanned surface and
underwater vehicles to maximize search effectiveness in maritime environments. In 2017, a
research team from the Air Force Engineering University in China conducted a study that
determined that UAVs can be far more effective than manned aircraft in maritime search-and-
rescue operations (Lei, Jianbo, & Shukui, 2017). According to Lei et al. (2017), the ability of
UAVs to maintain sustained operations while providing both automatic and manual scanning
greatly increases the odds of rescuers finding lost personnel. By utilizing both a UAV and a
UUV, rescuers can systematically search large areas of water for longer periods of time (and at a
much lower cost) than by utilizing manned craft for the same purpose.

UUVs have many advantages over their manned counterparts when it comes to maritime
operations. They are generally far less expensive to operate than manned craft and present no
danger to pilots or crew while operating (McPhail, 2002). They are also small and compact in a
way that manned craft cannot be. The Bluefin-12(D) is small enough to be maneuverable
in tight spaces, a potentially crucial ability when attempting to navigate wreckage. A craft the
size of the Bluefin is far too small to accommodate a human crew.

The story of the Argentine submarine does not have a happy ending; the US Navy called
off its search for vehicle six weeks after it disappeared (Chaplain, 2017). As of May of 2018,
the submarine is still missing, with little hope of survival for its forty-four person crew
(Goldman, 2018). However, while this operation may have failed thus far, the increasing use of
UUVs in maritime search and rescue operations may increase the number of lives saved in the
future.


                                                                 References

Chaplain, C. (2017). US Navy ends search for missing Argentine submarine ARA San Juan.
     https://www.standard.co.uk/news/world/us-navy-ends-search-for-missing-argentine-
     submarine-ara-san-juan-a3727766.html

General Dynamics (n.d.). Bluefin-12D autonomous underwater vehicle (AUV). Retrieved from
     https://gdmissionsystems.com/en/products/underwater-vehicles/bluefin-12-d-autonomous-
     underwater-vehicle

Goldman, J. (2018). 6 months after Argentine submarine went missing, families feel ‘invisible’.
     https://abcnews.go.com/International/months-argentine-submarine-missing-families-feel-
     invisible/story?id=55146472

Lei, Z., Jianbo, H., & Shukui, X. (2017). Marine search and rescue of UAV in long-distance
     security modeling simulation. Polish Maritime Research, 95(24), 192-199.

McKirdy, E. (2017). Argentina’s missing submarine: what we know. Retrieved from
     https://edition.cnn.com/2017/11/20/americas/argentina-submarine-what-we-know/index.html
     on 18 November, 2018.

McPhail, S. (2002). Autonomous underwater vehicles: are they the ideal sensor platforms for
     ocean margin science? Ocean Margin Systems, 79-97.

US Navy. (2017). US Navy deploys unmanned submersibles in Argentine submarine search.
     Retrieved from https://www.navy.mil/submit/display.asp?story_id=103420

Werner, B. (2017). US Navy undersea teams now underway as part of Argentine submarine
     search. Retrieved from https://news.usni.org/2017/11/22/u-s-navy-unmanned-underseateams-
     now-underway-part-argentine-submarine-search

Original article: A self-driving car in every driveway? Solid-state LIDAR is the key.

Author: Nick Mokey

URL: https://www.digitaltrends.com/cars/solid-state-lidar-for-self-driving-cars/

                                                                       Summary:

LIDAR is an exteroceptive sensor that is crucial in the operation of self-driving vehicles. It works on the same principle as radar, but utilizes light instead of radio waves. Here is an image of a conventional LIDAR system on an autonomous vehicle:

The module you see on top of these cars is the LIDAR system. It spins rapidly while emitting beams of light. As this light bounces back towards the system, the LIDAR calculates the positions and angles of the reflected light to create a three-dimensional image of the car's surroundings. The car then uses this data to plot a path through its environment. LIDAR is a key exteroceptive sensor on many self-driving cars.

It is also unreliable and expensive. A conventional LIDAR system requires many moving parts, all built around a console that must spin very rapidly in order to work properly. Any system with multiple parts and a high rate of spin speed is potentially prone to many different types of failure. And the cost of one system (upwards of $75,000) means that it costs more than many of the cars to which it is mated. LIDAR is critical technology, but is unrealistic as a mass-market solution in its current form.

Enter solid-state LIDAR. This is what a solid-state module looks like:

This solid-state system, developed by Veoldyne, is one of many modules currently in development. It is a fraction of the size and a fraction of the cost of a conventional spinning LIDAR.

So how does it work? Simply put, "solid state" means no moving parts, and a solid-state LIDAR works by utilizing an array of light emitters to scan a focused slice of the surrounding environment. According to Quanergy, a manufacturer quoted in the article, this drives the price point of a single solid-state LIDAR system to under $1,000, with technology improvements lowering the price further still. A solid-state LIDAR system can only see a limited slice of its environment (something like 90-120 degrees, depending on the unit), necessitating the use of multiple systems for full 360-degree coverage. However, given the unit's size and price point, it is still far more practical and cost effective to install three or more solid-state units on a car than to use just one conventional LIDAR system.

The vast majority of automobile manufacturers agree that LIDAR is key to fully autonomous, self-driving vehicles. LIDAR is a key extereceptive sensor in these vehicles, and solid-state LIDAR promises to make self-driving cars affordable to the masses.

Unmanned Aerial Systems: The Wave of the Future, for Better or Worse

Development of unmanned systems is progressing forward at a rapid pace. The market is exploding with new models in the air, ground, and maritime domains. Flying drones, both commercial and hobby, are becoming cheaper and more available; ground drones are being used as delivery systems; and maritime drones are entering military service in both combat and search-and-rescue roles. However, although drone technology is exploding in all domains, it is the unmanned aerial systems, or UASs, that will be the dominant drones of the future. And they will be dominant because of two key words: versatility and range. 

UASs are the most versatile of all the drone types on the market. For example, one look at the H Robotics website (http://www.hrobotics.co.uk/index.html) shows that they offer their drone in nine different configurations, including broadcasting, surveying, and gas leak monitoring. Professional photographers use drones to take images that would be either prohibitively expensive or outright impossible without UAVs (Bernstein, 2015). Search and rescue units are using drones to locate missing persons (Hodapp, 2015). The list goes on. Unmanned ground systems (UGSs) and unmanned maritime systems (UMSs) can also be used in a variety of roles, but none are as encompassing as the UAVs. 

UAVs also have the biggest range, by far. UGVs are limited to operating on the ground and UMVs are limited to operating in water. However, UAVs can affect all three domains. UAVs can be used for search and rescue operations over water as much as over land; they can be used for deliveries to ground locations; and they can go farther and faster than either of the other two types of unmanned systems. 

I think UAVs will have the greatest impact on society over the next two decades. UAVs are the most popular, most common, and most well-known drones on the market. They can be seen in every toy store, and more and more companies are using them for commercial purposes. I think they will be most commonly used in a photography/videography/surveillance role, since we as a society love taking and sharing images.

What impact will this have? I believe it will have a similar impact to that of smartphones. The smartphone was (and is) a world-changing device, because it gives users the ability to take high-quality images and videos and share them instantly with the rest of the world. This has eroded privacy, but it has also uncovered injustice and led to the exposure of serious issues that would otherwise never come to light. I believe UAVs will do the same thing. The ability of these drones to take high-resolution pictures from virtually any angle will lead to more and more people living their lives in a sort of fishbowl, constantly mindful of the fact that someone is watching. This is bad for privacy but good for justice and law enforcement. It’s a double-edged sword.

Ultimately, I think UAVs will be the most impactful because they most closely align with human nature. For whatever reason, people love to take pictures and observe each other. UAVs make that possible more than any other unmanned system, which is why they will be the most impactful drone in the future.

References

Bernstein, B. (2015). Top 3 best drones for drone photography and 4K video. Retrieved from

    

     http://heavy.com/tech/2015/07/top-best-drones-to-buy-for-drone-photography-4k-video-

     

     surveillance/

Hodapp, P. (2015). Search and rescue teams aim to save lives with off-the-shelf drones.

     Retrieved from https://makezine.com/2015/12/15/search-and-rescue-teams-aim-to-save-lives-

     off-the-shelf-drones/

Studying Orcas with the Wave Glider SV3

            Orcas, more commonly known as killer whales, are some of the most intelligent and mysterious creatures in the ocean. Orcas are a very culture-oriented species, with different pods developing different preferences for food, different migratory patterns, and even different dialects (Stiffler, 2011). In fact, when it comes to language, orcas may be as sophisticated as humans (Crawford, 2013). Some scientists have devoted their entire lives to cracking the code of the orca language and learning how to speak to these animals, but to no avail. Where humans have failed, however, drones may succeed, especially one drone in particular: the Wave Glider SV3 by liquid robotics.

The Wave Glider is a fully autonomous surface unmanned maritime vehicle (UMV) that has achieved record-breaking feats of autonomous sailing (Coxworth, 2012). Highly modular, it can be fitted with a variety of devices for observation and research. It can also be fitted with recording devices capable of recording the sounds made by killer whales when they communicate. This data, gathered over long periods of time, may give researchers the key they need to finally understand what orcas are saying to each other.

But how would such a research plan be implemented? And how would it deal with four key issues of drone use, namely privacy, ethics, safety, and loss of link/loss of system control?

Step one, in my opinion, is to introduce the Wave Glider into waters near the orca pod it is directed to follow. The drone needs to be close enough to the pod to record both video and audio and to allow the whales to become accustomed to its presence, but far enough away to not be considered a threat. This keeping of distance would preserve the whales’ privacy, which is key to keeping the drone operational. If the orcas perceive the Wave Glider as a threat, the drone will literally be dead in the water.

Step two is to follow the designated pod. This would present the most difficult challenge, as killer whales travel much faster than the Wave Glider. The best solution here may be to leave the UMV in the whales’ territory, knowing that they will come back.

Step three is to record and transmit as much audio and video data as possible. Linking visuals to sound is key to interpreting what the whales are saying, and the more data is gathered, the better.

It’s a simple plan, but I think it can work, once the other aspects of drone use are taken into consideration.

We’ve already covered privacy; the Wave Glider needs to respect the privacy of the whales, or risk being upended and torn apart. What about ethics, however? Is it ethical to spy on these animals (which some believe have the intelligence of humans) to try and decipher their language?

I believe the answer is yes, as long as that knowledge is put to ethical use. If we ever gain the ability to communicate with killer whales, we can use that ability to guide them out of potentially dangerous or overfished waters and to a location more suitable for the pod.

Safety plays a big part in this project as well, with the safety of the whales and other marine life being paramount. Again, if the whales regard the Wave Glider as a threat, they may smash into it to damage it and hurt themselves in the process. This is where gradual introduction of the Wave Glider in the orcas’ environment is crucial. I know from experience that orcas will tolerate small boats within a few hundred yards of their location, because I did a kayak whale-watching tour in 2014 and watched them do exactly that. The key: the whales were used to seeing the kayaks, and knew that they weren’t threats.

Loss of link/loss of system control is the final consideration, and an important one. Losing connection to the drone would negate the value of the experiment. Loss of system control may mean the drone wandering out of the whales’ territory, or worse – getting too close to the whales and getting demolished in the process. This can only be mitigated by periodic human monitoring and blind luck. Having a human repair and retrieval team on standby would negate the efficacy and cost savings of the experiment; if a human crew can be in the water watching the drone, it can also be in the water watching the whales themselves. Periodic monitoring, however, would identify problems within a reasonable amount of time and give a response team the chance to go to the drone and correct the issue. Ultimately, though, being problem-free will come down to preparation and luck. Prepare the drone for the mission as best as possible, then trust luck to take it the rest of the way.

Killer whales talk, but no one knows what they’re saying. The Wave Glider SV3 can help change that.

References

Coxworth, B. (2012). Wave Glider aquatic robots set world record. Retrieved from

     

     https://newatlas.com/wave-gliders-set-record/21840/

Crawford, L. (2013). Killer whales are non-human persons. Retrieved from

         

     http://greymattersjournal.com/killer-whales-are-non-human-persons/

Stiffler, L. (2011). Understanding orca culture. Retrieved from

     

     https://www.smithsonianmag.com/science-nature/understanding-orca-culture-12494696/

     

Do We Really Need Humans to Explore Space?

Is it worth the time and expense to send humans into space? This question has been debated for a long time, and continues to be asked as robots grow more sophisticated. The central question is this: is there any justifiable reason to sending men and women to other planets, or is exploration best left to the machines?

Robin McKie may have an answer, and that answer is robots. In his 2014 article on the subject, he lists many of the advantages of unmanned space exploration. Some of these include:

Cost. It is far less expensive to send a robot into space than a human, because a machine does not require food, environmental control, or basic safety measures. Robots can travel lighter, which means they can travel farther at a lower cost (McKie, 2014).

Range. McKie (2014) also points out that robots can travel farther and work in far harsher environments than humans. As a result, they have explored environments like Saturn’s moons, where robot probes discovered hydrocarbon lakes.

Sophistication. McKie (2014) also states that exploration robots have become very sophisticated, evolving far beyond their primitive ancestors of two decades ago. These days, a robot can execute just about all the science experiments that in years past could only have been done by humans.

From a practical perspective, I believe that robots are the better choice. I think that exploration should be an exclusive domain of machines. My biggest reason for saying this is the fact that supporters of manned exploration seem to rely more on poetry than data.

Noted astrophysicist Neil deGrasse Tyson said this of manned spaceflight: “humans are endowed with the ability to make serendipitous discoveries that arise from a lifetime of experience” (Tyson, 2012). Those are beautiful words, but they don’t hold much weight when justifying manned spaceflight. Human beings can make “serendipitous discoveries” just as easily by sifting through the data sent back by the explorer machines.

Cosmologist Stephen Hawking echoed those statements: according to him, robotic missions “may provide more scientific information, but they don’t catch the public’s imagination in the same way…” (McKie, 2014). Again, we have the appeal to heart, without much hard data to back it up.

This pattern repeats itself often when the manned vs. unmanned debate pops up. Proponents of unmanned flight say that robots provide much more information than human astronauts, and at a fraction of the cost. Supporters of human flight point out that putting a man on Mars instead of just another robot would serve as an inspiration to all people.

Both camps make great points. The images of Neil Armstrong on the moon inspired untold numbers of young men and women to pursue science as a career. And landing a man (or woman) on Mars would, in my opinion, have a similar effect.

If push comes to shove, however, then I fall squarely into the robots-only camp. Robots are growing more sophisticated by the day, and computing power continues to accelerate. Decades ago, it would have made more sense to send people into space, due to the limits in computer power and robot design at the time. Now, however, putting human beings on Mars (and beyond) feels like a vanity project. It would be great to see human footprints on Mars one day, but not while those footprints come with a hundred billion-dollar price tag (Wall, 2012). There is no way to justify spending that kind of money when a robot can do the same mission at a fraction of the cost.

In my heart, I’m for manned space exploration. In my head, however, I know that manned exploration no longer makes sense. Space exploration is best left to the machines. Manned flight has lots of poetic and philosophical support, but unmanned exploration has numbers. And, in this case, the numbers win.

References

McKie, R. (2014). Astronauts lift our spirits. But can we afford to send humans into space?

     

     Retrieved from https://www.theguardian.com/science/2014/dec/07/can-we-afford-to-send-

     

     humans-into-space

Tyson, N.D. (2012). Neil deGrasse Tyson: only humans can truly explore space. Retrieved from

     

     http://nationalpost.com/opinion/neil-degrasse-tyson-only-humans-can-truly-explore-space

Wall, M. (2012). Should NASA ditch manned missions to Mars? Retrieved from

     

     https://www.space.com/16918-nasa-mars-human-spaceflight-goals.html

Airborne Drones: Tools, Not Toys

            When it comes to commercial airborne drones, the world seems to be pointing in one direction: delivery. Amazon wants to use flying drones to deliver packages (Manjoo, 2016). A company called TacoCopter is trying to live up to its name by using quad-rotor drones to deliver tacos (Mediati, 2012). Even Google is getting in on the action, testing their own delivery drone system (Barr & Bensinger, 2014). The big companies seem to think that delivery drones are the wave of the future.

            Dr. Pippa Malmgren sees the market differently. An economist and best-selling author, Dr. Malmgren firmly believes that delivering food and parcels isn’t where the drone market is heading. Instead, she believes that the true future of the drone is as a data-collecting tool (Malmgren, 2017). I want to focus on her arguments, because she has literally put her money where her mouth is: Dr. Malmgren is one of the founders of H Robotics (website link: http://hrobotics.co.uk/), which develops and sells drones aimed at the commercial market. Here is what the base H Robotics drone looks like:

                                          Image source: Malmgren, 2016

In her 2016 article, Dr. Malmgren makes the following statement: “…just as you would not confuse a Chevy and a Ferrari, you should know that drones are very different from each other”. This is a statement with which I wholeheartedly agree. As we have already seen in both this blog and others, multiple companies are developing ground and sea-based drones for all types of commercial purposes; it’s not surprising to the see the same kind of development with commercial quad-rotor unmanned aerial vehicles (UAVs).

            Dr. Malmgren also states, in both her 2017 and 2016 articles, that she doesn’t think the idea of drones as delivery vehicles will take off (pun intended) because they are dangerous. A thirty-plus-pound drone, flying over a residential neighborhood, presents all kinds of hazards; children and dogs will be drawn to it, and if it falls, it will leave serious damage in its wake. To make her point, she posts a video of a camera drone almost crushing slalom skier Marcel Hirscher. It is a very convincing video, so I am linking it here. 

https://www.youtube.com/watch?v=xeviAWB0i4Y

Given how many drones would have to fly on a daily basis to meet Amazon’s delivery demands, it is inevitable that some would crash and cause injury, especially since so many of them would have to fly over heavily populated areas. I find myself agreeing with Dr. Malmgren here as well; delivery may well be left to the ground-based drones. At the very least, aerial drone delivery sounds as if it will be far more complex to pull off than we even think today.

            What then is the future of the quad-rotor drone? As I stated earlier in this blog, Dr. Malmgren thinks that the answer is data collection. She envisions her drones being used for broadcasting, mine valuation, search and rescue, and insurance analysis (Malmgren, 2016), to name just a few functions. The desired end state is a highly modular and customizable drone that can be used for anything the user can imagine. Her goal appears to be to make the H Robotics drone a quad-copter Swiss Army knife of sorts.

            This is where I think aerial drones are headed as well. The H Robotics drone is highly customizable and modular, which I think is the key to all these platforms. The most successful drones will be the ones who allow the customer to use them for whatever they envision, rather than dictate to the customer how they should use the system. Drones that allow for user creativity will be the ones that thrive; human imagination is limitless, and drones can be that imagination’s next tool.

References

Barr, A. & Bensinger, G. (2014). Google is testing delivery drone system. Retrieved from

     https://www.wsj.com/articles/google-reveals-delivery-drone-project-1409274480

Malmgren, P. (2016). Drones and the coming 4D world. Retrieved from

     https://www.linkedin.com/pulse/drones-coming-4d-world-pippa-

     malmgren?articleId=7552070594417338614

Malmgren, P. (2017). Commercial drones: the smallest and most profitable part of the drone

     market by the founder of @H_Robotics. Retrieved from

     https://www.linkedin.com/pulse/commercial-drones-smallest-most-profitable-part-drone-

     pippa-malmgren?trk=mp-reader-card

Manjoo, F. (2016). Think Amazon’s drone delivery idea is a gimmick? Think again. Retrieved

     from https://www.nytimes.com/2016/08/11/technology/think-amazons-drone-delivery-idea-

     is-a-gimmick-think-again.html

Mediati, N. (2012). TacoCopter deliverys tacos by quadrocopter: is this for real? [updated].

     Retrieved from https://www.pcworld.com/article/252412/tacocopter_delivers_tacos_by_

     quadrocopter_is_this_for_real_.html