This week's activity was less of a field exercise and more of a research project. We were tasked with conducting research on our own to gain a better understanding of unmanned aerial systems (UAS). In addition to utilizing the software, Real Flight 7.5 to test fly various platforms we were also challenged with addressing real world scenarios which would utilize different UAS technologies. This activity allowed us to get hands on experience using UAS in the flight simulator while also conducting research to better understand how this technology can be used in the field. In addressing the various scenarios we were tasked with determining the best type of UAS platform and other materials that should be used which would be most fit for the project at hand. Throughout this activity we were able to not only expand our knowledge of UAS but also apply this knowledge to address real world situations.
Overview of UAS
Unmanned aerial systems utilize unmanned aerial vehicles (UAVs) which are aircrafts that have the ability to fly autonomously, or without pilot control. Most UAVs which are amateur are neither military nor commercial and are typically able to fly under the "recreational" exception to the FAA regulations. A common misconception is that these amateur air crafts are able to be flied anywhere by anyone, however the FAA regulates that the UAVs have pilots and programmers within the area to monitor the altitude and distance in which the UAV flies in order to stay within the FAA limits. To operate these crafts, most of the time they are manually flown using remote control to take off and land but when in the air GPS-guided flight plans are utilized to allow the UAV to operate autonomously once at a safe altitude. While they can be in autopilot and navigated based on predetermined flight paths, they are still capable of being flown manually and often are flown this way. Software which equips the UAV with the autopilot capability can either come with the UAV itself or be purchased separately. There is also other software which can be used in mission planning which is quite essential for the use of the aircraft in order to pre-program a certain flight path. As the UAV is flying programmers and pilots are able to remotely analyze the data in real time using various types of graphical interfaces.
Common Types of UAS
Fixed Wing Aircraft
Fixed wing air crafts are basically small planes which are unmanned. Some major benefits to this type of UAV is that they can fly for long periods of time based on how they are powered, they can carry greater payloads than most rotary crafts and they can usually and can more efficiently utilize the power it is given. These types of crafts can be powered by both batteries and gas which can allow for 1-10 hrs of flight time. Since they are able to glide if there is a loss of power they are much more forgiving in the case that there is some type of problem while it is in flight. Some downfalls of this particular UAV include the fact that they require an area that can act as a runway in order to take off and they can vary greatly in price.
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| (Fig. 1) This is an example of a fixed wing UAV. This is the APM Plane which can be found at the following link: ArduPlane. |
Another type of UAV is a helicopter which are single rotary aircrafts. This means that they have a single motor which lifts the craft with 2 or more blades. A major benefit to this type of craft is that they are capable of vertical takeoffs and can hover to capture more detailed images from below. Hovering also allows for more real-time feedback which can be analyzed by the pilots and others who are present at the flight. Like the fixed-wing UAVs they can be powered by either gas or electric however their flight time is heavily influenced by the amount of weight they are carrying. This particular type of UAV is very versatile and can carry various weights of equipment, reach high speeds and achieve long flight times depending on the model.
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| (Fig. 2) This is an example of a helicopter UAV. More information about this particular model can be found using the following link: UAS Vision. |
Multicopters are very similar to helicopters however they utilize 4 or more completely separate motors to provide the lift for the craft. There is a great deal of variety in the different types of multicopters which include those with anywhere from 4 to 8 motors that can have greater payloads and increase the overall stability in flight. Due to the increase in the number of motors compared to the helicopter they are able to stay extremely stable even in very strong winds but they do require an on-board computer system in order to fly. Since they have so many motors however, they do not typically have very long flight times but they are able to take very detailed images based on their very stable hovering capabilities. The most common type of multicopter is the quadcopter which has only 4 motors, is the most user friendly and the least complicated.
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| (Fig. 3) This is an example of a quadcopter, which is a type of multicopter which utilizes a total of 4 different motors. More information about this particular model can be found using the following link: Robot Shop. |
Flight Simulator
In this portion of the activity we had the opportunity to get some hands on experience with various types of UAVs without actually flying them. Using the Real Flight 7.5 we were able to practice our flying in different environments and with different platforms or aircrafts. I decided to use a helicopter, fixed wing UAV and some other crafts to test out my ability to fly. It was also very interesting to adjust the wind speed as well as change the flight environment. Within this software we were also able to adjust the camera angles from which we viewed the plane we were flying which was an another interesting variable. I really enjoyed the opportunity to work with this software because it gave me a lot of insight that I was able to apply to the various scenarios below since I now had a better understanding of how the different types of UAVs operate.
Flight Log
Within my flight log I kept track of various elements of all my flights which included: flight number, craft type, environment I was flying in, wind speed in mph, view I was using to fly the aircraft, the amount of flight time I had, if I crashed or not and if so the reason for the crash. All of this data was very important to organize properly so I can better understand how my flying is and what I need more practice on. As can be seen in Fig. 4 I require much more flight time to be logged before I fly an actual UAV.
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| (Fig. 4) My flight log from using the flight simulator, Real Flight 7.5 which tracked my aircraft type, location, wind speed, flight time and any crashes I had including the reason for the crash. |
Scenarios
Scenario 1:
A pineapple plantation has about 8000 acres and they want you to give them an idea of where they have vegetation that is not healthy, as well as help them out with when might be a good time to harvest.
The first thing to address in this scenario is how to determine whether or not the pineapples are healthy or not. Once this has been addressed it can be decided how these techniques can be applied to and utilized with a UAV. Based on background knowledge of remote sensing it is clear that the NIR (near infrared) band of the electromagnetic spectrum is the best way to monitor vegetation health. This is because it has a longer wavelength than visible light. The reflectance in this particular band is so useful in tracking vegetation health because plants are a strong reflector of light of the NIR wavelength. This means that when the NIR wavelength of light hits the plant most of it is reflected off the plant rather than being absorbed. The interaction between the plant cells and the NIR light cause this greater amount of reflection. Based on the amount of reflected light it can be determined that plants that are healthy will reflect more of the NIR light while plants that have damaged cells and are therefore unhealthy allow more NIR light to be absorbed into the plant and therefore not be reflected.
By utilizing a NIR camera the plants which appear bright are those which are healthy while unhealthy vegetation will have the opposite appearance. Monitoring the amount of reflected light in the NIR wavelength we will be able to track the health of the pineapple plants in the plantation. To apply this idea with looking more closely at how to determine when the pineapples are ready to be harvested or not the NIR camera can also be used. Pineapples that are ready to be harvested will appear at least 1/3 yellow in color. By looking at the reflectance data it would be fairly simple to look at the areas where there is a greater amount of yellow light being reflected to decide if the plants in that area should be harvested.
UAS are a great way to collect the data which was discussed above. When deciding which particular type of UAV would be best suited for this particular scenario we must think about a few key factors: how large is the area and how long will it need to be in flight. I would not recommend the use of a fixed-wing aircraft because there is not a good area where a fixed-wing aircraft could take off. Since very precise images are need in order to properly analyze the NIR reflectance values I think that a quadcopter with an infrared camera mounted on the bottom of it would be the best option to capture the necessary data. A quadcopter has much more stability and based on the shape it is easy to mount a camera to the bottom of it so we can gain images of the land directly below where the UAV flies. I believe this to be a better option than using a helicopter because they are much more stable and able to support much greater payloads like that of the infrared camera.
Scenario 2:
A military testing range is having problems engaging in conducting its training exercises due to the presence of desert tortoises. They currently spend millions of dollars doing ground based surveys to find their burrows. They want to know if you, as the geographer can find a better solution with UAS.
Desert tortoises can be found in the deserts in the western United States and area able to survive in quite extreme habitats that other species would have trouble living in. Since it has been found that desert tortoises spent up to 95% of their lives inside their burrows it is of great importance, especially in this scenario, to locate such burrows. Construction of these underground homes for the tortoises requires a special type of soil which is a mixture of gravel and clay rather than sand which can collapse too easily. Biologists have also found that they prefer to construct their burrows around shrub vegetation.
In order to locate these burrows it would be necessary to employ a fixed-wing aircraft which could quickly analyze a very large area. It would be most beneficial to also have a UAV that is gas powered rather than battery powered so that the flight time can be increased since the area of study is so large. The best way to locate these burrows would be to focus on areas where there are shrubs since 97% of the burrows are found near this type of vegetation however it is also important to determine the soil type in the area and the depth of the soil to more accurately locate these desert tortoise homes. In order to do so I would recommend attaching a multi-spectral scanner to the fixed-wing aircraft. Using the thermal band of the electromagnetic spectrum we could gain a better idea of where the tortoises are actually located beneath the surface. It would be important however to collect data at dusk when the ground is cold so that the body heat of the tortoises can better be pin pointed without the heat of the ground disrupting the accuracy of the collected data.
By analyzing the data collected by the multi-spectral scanner mounted to the fixed-wing UAV we could determine the most appealing areas for the desert tortoises to create a burrow. Then by combining this data with that of thermal data collected we could determine the ideal habitats for the burrows and where the individual tortoises are actually located. We could even further look at the soil nutrients and soil types to determine the best areas where the tortoises would want to dig their burrows. This location information could then be relayed to ground crew teams who would then not need to search nearly as large of an area to find the tortoise burrows and therefore less money would need to be spent on their labor.
Discussion
There is a great deal of variation in the types of UAVs but it is clear that they can be used for a wide variety of real world situations. For the first scenario we were tasked with how to monitor the health of a large plantation of pineapples. I determined that in this particular situation a multicopter, particularly a quadcopter UAV would be best when using NIR imagery in order to determine how healthy the pineapples are. Using this NIR information it would also be possible to track the growth of the plants and decide when it is time for the fruits to be harvested. In the second scenario, I was tasked with determining how to locate desert tortoise burrows in a large area. I decided that since it was such a large area to survey that a fixed wing aircraft would be best, especially if it were gas powered which would allow it to cover more area in a single flight. Also, the fixed wing aircraft would need to be fitted with something to detect the visible near infrared band of the electromagnetic spectrum which would allow for greater analysis of the soil types in order to locate the burrow locations.
In these practice scenarios it was very important to use my previous knowledge of remote sensing techniques, geospatial analysis tools and the information I gained of UAV systems throughout this activity. The scenario exercise was a great way to really challenge my ability to think critically and remind me how important it is to really think about all aspects of the situation and apply all my knowledge toward solving the problem at hand.
Conclusion
While this activity might not have utilized traditional field work to gain a better understanding of unmanned aerial systems I found this lab very informative. The research portion of this activity required a great deal of research to be conducted and allowed us to gain a better understanding of just how much variety there is in the world of UAVs. Each scenario offered a very realistic situations which we were able to apply all that we learned to it and determine how we would create a proposal for a future employer. I also found it extremely useful to use the flight simulator to gain a better understanding of the benefits and negative features of the different types of UAVs.
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