This class is a upper level geography course that teaches the basics of how to do field work. This week's lab was a field day at a local mine designed to show the students how to do basic GPS survey and to introduce them to a variety of Unmanned Aerial System platforms and one robotic total station. With technology advancing faster than ever, today's survey techniques are very advanced and accurate. With the use of UAS (Unmanned Aerial Systems) a mine can be surveyed in a few hours with centimeter accuracy. This lab was designed to show the differences between multiple GPS and UAS platforms.
Both sections of Field Methods met at the Litchfield mine on a Saturday, September 30th. This mine is located just southwest of Eau Claire WI.
Methods:
To begin the day the class walked around as a whole and placed out Ground Control Points for later use with the drone imagery. The GCP's were set out in a way that none of them were clustered together in one area and they were spread on a variety of surfaces. Some on top of piles of material and some on the low ground. To get accurate measurements of piles, GCP's were placed on top, and around the largest piles. A GCP is just a square that is placed on the ground that is taken with a GPS. This makes it a known point and allows the imagery to be tied down to where it is in the world accurately. After laying down the GCP's, the class was split into groups to go take coordinated of the GCP's with a variety of GPS's. These GPS's included:
-Iphone
-Bad Elf GPS Unit
-Trimble R2
-Septentrio Altus NR2
-Arrow GPS Markers
-Topcon HiPer
The accuracy of these GPS's are to be compared when the data is processed at a later date. Some of these units have sub-cm accuracy and some have around 10m accuracy. The purpose of this lab and field day is to compare what units are actually more accurate. The following link is a link to the Bad Elf and Iphone GPS Coordinates. The other data is not yet processed.
https://universityofwieauclaire-my.sharepoint.com/personal/bealir_uwec_edu/_layouts/15/guestaccess.aspx?guestaccesstoken=W9LCwEn%2f9mv843morGhbvirEw7%2bbscnLlBTRUwJL2qI%3d&docid=2_09c2590b8e4a049eda216cf5714bb358f&rev=1
The following map is a hand drawn map of where the GCP's were located. This is to help find the GCP's when processing the imagery.
Once the GCP's were recorded with a variety of GPS's, it was time to fly! The first UAS to fly was a DJI Phantom 3 Pro. DJI is one of the most popular brands of drone for public and commercial use. The Phantom series is their most popular drone. With about a 25 minute flight time this drone is a great portable drone for taking aerial imagery. There are a variety of flight planning apps that allows the pilot to create a grid that the drone will follow for mapping. The program has the drone take off, fly the pattern, and land. The image overlap, flight height, speed and other settings are set during the mission planner. This is an affordable platform ($800-$1200) that is good for basic mapping applications
 |
| Phantom 3 Pro |
The second UAS to fly was a SenseFly eBee. This a fixed wing aircraft with a foam body that requires little to no flying skill for the pilot. The Pilot in Command creates a flight plan using the app that the UAS comes with from SenseFly. This is where the pattern the drone is to follow is set, as well as things like height, speed, rally points, and other things the platform needs to fly. When the mission is planned the PIC (pilot in command) shakes the drone three times and throws it. The eBee knows its suppose to start the mission and takes off into the sky. The eBee is a high level mapping UAS platform that is capable of getting centimeter accuracy with RTK GPS capabilities.
 |
| SenseFly eBee |
The next platform to fly was a DJI Matrice 600 Pro. This is a few steps up from the DJI Phantom. It has more motors and is much larger. Instead of just one battery like the Phantom, this platform has 6. This almost doubles the battery life. Besides the battery life and more motors, this platform has RTK GPS capabilities making it up to cm accurate. A similar mission planning software is used for the M600 as the Phantom. One of the biggest differences between the M600 and the Phantom is the M600 can swap sensors. A bigger more powerful camera can be put in the M600. Different types of cameras for different applications can be put the in M600. This is one of the biggest benefits of this platform. The Matrice 600 falls in the range of $3000-$6000 depending on the sensor and GPS options it comes equipped with. Putting an upgraded sensor on it is always an option and that can range from $500 to well over $50,000 depending on the sensor.
 |
| DJI Matrice 600 Pro |
Last but not least the is the C-Astral Bramor. This is by far the most expensive UAS at $70,000. This is a high performance fixed wing drone capable of 3 hour flights. This is an ideal platform for mapping large areas with cm accurate data. This is a new drone on the market that Menet Aero displayed at the mine. It is a fiberglass bodied drone with a wing span of more than 5 feet. Equipped with RTK GPS this platform is for high end mapping applications. The Bramor comes with an advanced mission planning software that allows for unique mapping applications like corridor mapping. The most intriguing thing about the Bramor is it's parachute landing. This means that it can be used when there is not a lot of room to land.
 |
| C-Astral Bramor |
Conclusion:
Starting with the GPS units, the high end sub-cm accurate GPS's were very easy to use. Once a data collection app was set up, all the user needed to do was enter a few things about the point they were taking and hit submit. This automatically populated a feature class and stored the coordinates. This was easier than actually writing the coordinates down for the Bad Elf and Iphone. We will see what GPS unit was more accurate at a later date.
This day was plagued with bad luck for the Unmanned Aerial Systems. The Phantom flight went great once some technical difficulties were solved but once the fixed wings were pulled out things started to go downhill. The eBee flight was off to a rocky start when it suddenly did a barrel roll while flying its pattern. The pilot got concerned and told the drone to return to home. The drone did not want to listen and started flying very irregularly doing more barrel rolls and getting higher and higher. Suddenly the computer started chiming, "IMU FAILURE, IMU FAILURE" and the eBee started plummeting to the ground. This was a bad first impression of the SenseFly eBee. The drone was located by searching for it with the M600. The M600 performed flawlessly finding the downed drone and flying its mission.
The last drone flight of the day was the most exciting. The C-Astral Bramor is a large platform that performed great. It is launched by a catapult and then fly's its mission. It is very stable while flying even with a slight wind. Every thing went as planned until the landing. The Bramor started its decent as normal and once at the proper elevation came in for landing. The class watched eagerly for the chute to open. Panic ensued when the pilot said "Joe...the chute didn't open." The Bramor floated over the trees and into the woods. About 15 seconds later a loud crash could be heard in the distance. This was a freak accident that is still being investigated.
No comments:
Post a Comment