Introduction
Unmanned Aerial Systems are the new technology with collecting images and have proved very useful across disciplines. Different types of aircrafts exist and all have their advantages and disadvantages. The greatest difference is between the fixed-wing and multirotor systems.
Fixed-Wing Systems
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| Figure 1. Fixed-wing aircraft |
Advantages: Stable in high winds, large field of view, flies faster than multirotor systems, battery life is longer
Disadvantages: need landing and take off space, flight checks are longer, bigger turn radius
Fixed-wing systems contain a pixhawk, which is the brain of the aircraft. The pixhawk sends information to the base station quickly. These systems also contain a GPS setting and a compass to navigate. Their lithium batteries are heavy, and should be kept in the fridge for storage. This system is cutting edge with its ability to collect ozone readings and when analyzed can create 3D models of ozone.
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| Figure 2. Phantom DJI |
Multirotor Systems
Advantages: remote sensing, no distortion for small areas, more agile than fixed wing systems, needs less space for take off and landing
Disadvantages: slower, narrow field of view, shorter battery life
Multirotor systems come in many shapes and sizes. There are aircrafts with 4, 6, and even 8 multirotors. The propellers spin in opposite directions controlling the speed of the aircraft. A Jems sensor that takes infrared readings can be added to the multirotor system. This would be especially useful in biological studies.
Study Area
Date: 12 October 2015, 3-6pm
Location: Sandy Bank of the Chippewa River Valley (underneath the footbridge of UW-Eau Claire's Campus)
Conditions: Clear skies, Average temp. 60°F (retrieved from Weather Underground)
Methods
Demonstration Flight and Pix4D
On Monday, October 12th our class went to the bank of the Chippewa River (underneath the UWEC footbridge) to manually run the DJI Phantom. This was used to demonstrate the possibilities of data collection with images. The DJI Phantom was fairly simple to operate as its operator had control of moving it forward, backward, and was able to turn the Phantom as well. A camera was secured to the DJI Phanom and that is how I was able to collect the aerial data over the bank of the river. The Phantom leans forward while it is moving, but our professor informed us that the camera dock stays parallel to the ground and automatically adjusts for the angle.
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Figure 3. Field Methods Class on the Chippewa River Bank
experimenting with the Phantom DJI. |
Dr. Hupy took many images around the bank of the river. We had two principal areas to focus in on, a "24" made in the bank with rocks, and the sandboxes from our previous assignment. We also were able to take photos of a bids nest in a tall tree about 10 meters from us. Dr. Hupy had an iPad set up to the camera, so we could see up close what was in the nest.
Pix4D was used to process the images from the flight demonstration we did as a class with the DJI Phantom. On the sand bank of the Chippewa River (underneath the UWEC footbridge) the rocks were organized in a "24" with a circle surrounding the number, which can be seen in the figures below.
To process the data we created a new project in the program and named it, "Flood Plain Data". We had to specify the platform, site, and date (Flood Plain Phantom 10/15) and saved it within our personal student folders. We had to add at least three pages, and then we were ready to add pictures to Pix4D. The pictures were copied into our personal student folders as well. I chose to upload around 50 photos from the 24 pattern picture collection. Then we set the it to make a 3D-Map and adjust the GCP's to make it more accurate and let the program run. The data was processed in roughly two hours and exported right into my student folder. Pix4D generated a mosaic rater and a DSM. Both rasters were opened in ArcScene to display them in 3D. For the DSM raster, the hillshading effect was increased to 2.5 to show the micro-topography of the rock pattern.
Metadata
Who: Joe Hupy
What: Unmanned Aerial System
Where: University of Wisconsin-Eau Claire Geography Department
When: 15 October 2015
Why: To familiarize ourselves with the UAS technology
Discussion
The DSM and mosaic rasters generated by the Pix4D very accurate. The technology of using a multirotor aircraft has incredible applications, whether it is scanning a river bank or peeking into a birds nest.
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Figure 4. DSM from Pix4D of 24 rock pattern
of the Chippewa River Bank.Created with ArcScene,
hillshade = 2.5. Higher areas are darker. |
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Figure 5. DSM from Pix4D of 24 rock pattern of the Chippewa River Bank. Created with ArcScene,
hillshade = 2.5. Red is higher topography. |
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Figure 6. Mosaic from Pix4D of 24 rock pattern of the Chippewa River Bank. Created with ArcScene.
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Mission Planner
We used Mission Planner to explore how UAS are managed and how the flight plans vary with different settings (aircraft, altitude, speed, etc.).
In Flight Plan we zoomed into a football field near the UW-Eau Claire Campus. We wanted to find an undisturbed area to practice setting up a UAS flight mission. Right-clicking and selecting the Survey Grid(2) will open a new window to allow you to regulate the flight settings. As shown below in Figures 7 and 8 the yellow lines represent the flight lines or the route of the aircraft.
Discussion
Increasing the speed of the flight plan decreases the flight time, so this is important to take into consideration when planning a mission. Also, some UAV's have a shorter flight time to begin with which emphasizes the flight mission needs to cater to the goals of the mission and what data you are trying to collect.
Altitude is an essential part of the flight plan as well. As the UAV increases in altitude less area is covered in the flight plan and less images are taken. The more images taken the quality decreases.
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| Figure 7. A flight plan created using Mission Planner Software with a short flight time, few images, and a high altitude. |
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| Figure 8. A flight plan created using Mission Planner Software with a longer flight time, many images taken, and a low altitude. |
Real Flight Simulator
The Real Flight Simulator enabled us to try working a UAV without and real damage done. (I may have crashed a few times). The Flight Simulator was a great tool in learning how to run different types of aircrafts (there are many to choose from) and the different scenes available helps challenge the pilot.
Multirotor Aircraft
First, I flew the Q4 Quadcopter 520. It took about 10 minutues before I successfully took off. Flying UAV's is all about patience and taking off smoothly. I chose the Sierra Nevada Cliff to start, so I did not have to worry about running into trees or other objects.
The Quadcopter was difficult to turn but very stable. If you let the controls go the aircraft would hover in one spot. In the simulation the Quadcopter seemed to be moving very slowly, this may be because of the certain aircraft. The right lever of the controller propelled the quadcopter forward and backward and the left lever rotated the aircraft 360 degrees in the same place.
Multirotor aircrafts are very stable, can hover and rotate 360 degrees which would allow many practical applications in the field collecting data.
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| Figure 9. H4 Quadcopter in the Sierra Nevada Cliff Simulation (Nose View). Real Flight Launcher 7.5 |
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| Figure 10. H4 Quadcopter in the Airport Junkyard (Chase View). Real Flight Launcher 7.5 |
Fixed-Wing Aircraft
Second, I selected the Piper Club a fixed-wing aircraft. This was easier to control, however, the fixed-wing aircrafts are less stable and no quick movements can be made. The right lever tilted the plane to turn left or right and also you could increase or decrease the throttle. The left lever turned the rutter left or right and helped the plane increase or decrease in altitude. The speed of the fixed-wing aircrafts seemed to be much faster than the nultirotors.
Since the fixed-wing aircrafts were easier for me to fly, I chose different landscapes and was able to navigate around obstacles.
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| Figure 11. Piper Club flying in the Bayou (Chase View). Real Flight Launcher 7.5 |
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| Figure 12. Piper Club going through an obstacle (Chase View). Real Flight Launcher 7.5 |
Discussion
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.
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Figure 13. This is an example of a
Jems sensor to measure infrared levels. |
I would recommend using a multirotor system. Since the military is doing ground survey to locate the burrows, a multirotor system would be best because it could be stable flying only a meter or so off the ground. Another major benefit of using a multirotor aircraft would be with adding a Jems Sensor you could analyze the infrared data given from the burrows to locate them faster. Tortoises rely on warmer areas since they are exothermic (do not produce their own body heat). Finally, the cost of implementing a multirotor system should be less expensive than flying a fixed wing aircraft.
Things to take into consideration would be the flight time will be less than what it would be with a fixed wing aircraft and the field of view would be lower. Although, since the military was doing ground surveys it is probably not necessary to have a large field of view, just to quickly collect the data.
Conclusion
Overall, this lab activity opened my eyes to what technology is available to use for data collection. The multiple interactive parts of this activity helped in the learning curve and gave me a taste of what is possible. When performing this lab I could not help thinking the biological applications UAV's can give scientists to explore habitats, etc.
