Lab 4: Unmanned Aerial Systems Mission Planning

Introduction

The objective of this assignment is to introduce the students to how Unmanned Aerial Systems (UAS), Unmanned Aerial Vehicles (UAV), mission planning and get a basic understanding on how software such as Mission Planner, Real Flight Simulator and Pix4D work. This assignment will be broken up into two separate parts. The first part being, Dr. Hupy will manually fly a DJI Phantom over a study area taking pictures every so often, and then the second part will be using the software we have at the University of Wisconsin-Eau Claire to process the data. Mission planning and Flight Simulators will also be used during this lab.

Before entering the field we learned about several different UAS/UAV systems, including fixed wing,  multi-rotor (quad/hex copters) and what is the difference between an Unmanned Aerial Vehicle/System and an RC (radio control) toy plane.

Fixed Wing

The very first thing we learned about a Fixed Wing (wings that do not move) UAV was that they are not RC planes. The major difference between the Fixed Wing and an RC plane is that the RC plane does not have a computer on board which can be used to collect data. The Fixed Wing UAVs at the University of Wisconsin-Eau Claire have Pixahwk, which are the brains of the system. Everything the Fixed Wing does is related back to the flight station, whether it is being remote controlled or the on board computer is controlling the pre-determined flight plan, all the data is relayed back to the station. Newer UAVs are now starting to use replaceable/rechargeable batteries to lengthen the amount of flight time you can get, instead of having one fixed battery which has to be recharged every so often. The Fixed Wing we were shown had an average flight time of about 1.5 hours and have a cruising speed of over 14 meters per second (m/s). Lastly, we were shown how to get one of these Fixed Winged vehicles into the air, they do not have wheels and are too heavy to throw, so they have to rely on a bungee cord type launch mechanism, making it very difficult to use in small spaces such as cities and dense forests.

Multi-Rotor

In the lab we were shown two different multi-rotor UAVs. One had four rotors (quad-copter) two of the propellers were silver and two were black. This was to indicate that they spun opposite directions. Although not mentioned in class, I believe they spin opposite directions to assure a smooth and stable flight. The spinning of the propellers in opposite directions also makes this device capable of going any direction with the ease of a switch.

The other type of multi-rotor UAV we saw was a 6 engine one. This one, much heavier than the previously shown UAVs required two large batteries to operate with. This UAV has a much larger payload then the others, but with the increase of payload, we will also see an increase in power usage. The six-rotor UAV thus only has a flight time of about 35 minutes, less if you are attempting to carry some heavier equipment.

With all three of the seen UAVs, an increase in speed then means that we will see an increase in turning radius. The multi-rotors are capable though of slowing down and being able to hover, thus eliminating the large turn radius, but the fixed wing UAV is not capable of hovering, otherwise it will stall, so it must use a large turn radius if it is going to fast.

Part 1: Demonstration Flight

Under the University of Wisconsin-Eau Claire Walking Bridge, Dr. Hupy flew his DJI Phantom unmanned aerial vehicle (UAV). The purpose of this demonstration flight was to demonstrate how a UAV is flown as well as the tools and applications which could be used in this kind of situation. On board the DJI Phantom was a camera which can take pictures of what is directly below. The DJI took several pictures, a switch on the controller initiated when the pictures would be taken. In larger study areas, or different model UAVs, cameras can have settings to take pictures every so often (usually one every 0.7 seconds).

The DJI took over 200 images of two separate study areas; one study area was east of the walking bridge, capturing several parts of the shore, lake and grass areas. The other study area was west of the walking bridge where a couple students used rocks to make a large scale 24 with a circle around it.

Later on these images will be used in the program Pix4D to create a Digital Surface Model (DEM).

DJI Phantom (figure 1)

Pros

-The DJI phantom come as a basic quadcopter starting at $500, but can be upgraded to have a gimbal and a camera with the price still being under $2000.

-Relatively easy to fly for someone who has never flown one before.

-Due to its small size, it is very portable

Cons

-Not a whole lot of control

-installation can be difficult

Figure 1: DJI Phantom in box awaiting assembly

Fixed Wing Vehicles (figure 2)

Pros

-Long Flight Time

-Larger Payload

-Multiple different instruments can be installed to it

-Stable in Windy conditions

Cons

-Long set up/prep time

-Needs a large takeoff area

-Requires large turn radius

Applications

-Precision Agriculture Mapping

-Large Area Mapping

-Ozone Mapping

Figure 2: Fixed Wing UAV

Multi-Rotor Vehicles (Figure 3)

Figure 3: Multi-Rotor UAV

Pros

-Small Turn Radius

-Easy for beginners to fly

-Multiple sensors can be attached to it

Cons

-Small payload capabilities

-Shorter flight time

-Not stable in windy conditions

Applications

-Flying over volcanoes

-Asset Inspection

-Live Streaming events
when I was at Whistling Straits watching the second round I got to get an up-close view of one of the multi-rotor UAVs they were using to get shots of some of the holes along Lake Michigan.

-And one day delivering small boxes from Amazon...

Part 2: Software

After the seeing the DJI fly around on the banks of the Chippewa River, we went back into the labs at the University of Wisconsin-Eau Claire to learn about some of the software we can use to process images, create flight plans and even use flight simulators. In order to process the images we collected, we are going to use a program called Pix4D. This image processing software was used with the DJI Phantom to create a 3D view of the images taken.

Pix4D (figure 4)

Figure 4: The software we used to post process our gathered images

The software we used to create a Digital Elevation Model (DEM) along with other features, with the pictures taken by the DJI Phantom Vision Drone. Of the 200+ images taken, I used a total of 19 to create a point cloud file, which using outside programs such as ArcMap; we can turn it into a DEM raster.

The first step of using this software is to select the pictures you want to use from the file of pictures taken. Again for this I used 19 pictures taken, each containing a portion of the Circled 24 on the bank of the Chippewa River (figure 5).

Figure 5: Selected images to be used for post data collection processing

The next step in this process was to make sure all of the properties for each image were correct. Since the camera used stored data about altitude and coordinates, this step only required a simple click of the mouse on the next tab (figure 5).

Figure 5: A list of images ready to go onto post processing containing multiple forms of data

Other steps before the processing will take place include selecting the type of units you wish to use and what kind of maps you want to be created. The one selected for this project includes orthomoasic maps and a digital surface map (figure 6).

Figure 6: A list of the different types of maps you can make depending on how you run your data

Once done running, a serious of outputs were given in a PDF file, as well as saved as individual files in the selected workplace project folder (figures 7 and 8).

Figure 7: The mosaic and Digital Surface Model created from processing the images collected by the DJI Phantom

Figure 8: One of the maps created showed how much overlap there was between the images

Mission Planner (figures 9-11)

Many newer UAVs have on board computers which can fly themselves, well sort of fly themselves. In order for them to fly themselves we have to use a program called Mission Planner. Mission Planner is a computer software where you can plan your flights and figure out how much time it will take to fly as well as how many pictures you will have to take.

With the risk of other commercial or private flying instruments and vehicles, mission planning is very important. Typically “Drones” have a bad reputation in the eyes of the public, so planning and getting everything all set up is even more important. On the Mission Planner planning page, there are multiple red circles,

Figure 9: Opening Screen of Mission Planner

Figure 10: Study area for UAV flight

Figure 11: Proposed flight plan for a flight to take place in the Study Area

Real Flight-Flight Simulator

The worst thing that can happen to a UAV in terms of expense is crashing it and totally destroying it because you are not familiar with how it works. Luckily, we have Real Flight-Flight Simulators in the lab. This way you can practice (crash) all the UAVs you want without having to worry about damaging $1000s worth of equipment.

Real Flight is one of the most lifelike flight simulators on the market; using a similar control to a real UAV or RC vehicle it gives you the most accurate type of flying. You are able to choose from just about any type of vehicle imaginable. Flight options include hex copter, quadcopter, helicopters, all different types of planes, a gator driving a wind boat, and even a paper airplane.

Part 3: Scenarios

"A power line company spends lots of money on a helicopter company monitoring and fixing problems on their line. One of the biggest costs is the helicopter having to fly up to these things just to see if there is a problem with the tower. Another issue is the cost of just figuring how to get to the things from the closest airport."

First let us run through what we are trying to accomplish with this scenario. We want to come up with a cost efficient way to monitor and fix power lines.

The biggest issue here is the helicopter. Helicopters are expensive to buy, fly and maintain. They need take off space, which often times has to be done at an airport, they need expert pilots who are capable of flying them in such tight spaces. Very dangerous to fly near power lines, both for the power line and the people around. Lastly, if you are only checking to see if there is damage and there is none, you just wasted all that time and money on something that was no problem.

Through this lab exercise, I can suggest the use of Unmanned Aerial Vehicle for this scenario. Most likely a mutli-rotor vehicle because they can hover in place, easily maneuverable, they do not need a whole lot of take off space and can be relatively cheap (compared to a helicopter).

This video, not in English, shows a prime example of how a UAV can be used to inspect power lines with much more ease then the use of a helicopter.

Sources

https://www.aibotix.com/en/inspection-of-power-lines.html
http://www.cbsnews.com/news/amazon-unveils-futuristic-plan-delivery-by-drone/

http://copter.ardupilot.com/

http://fctn.tv/blog/dji-phantom-review/

https://pix4d.com/

http://www.questuav.com/news/fixed-wing-versus-rotary-wing-for-uav-mapping-applications

http://www.realflight.com/index.html