Activity 4: Unmanned Aerial System Mission Planning

Introduction

The use of Unmanned Aerial Vhicles (UAV) is and up- and- coming area in the world of technology. UAVs are remotely‐piloted aircraft fitted with sensors that can be used in many civilian applications. Some examples of regional industries interested in UAV technology include: agriculture, for precision agriculture operations; engineering firms, for surveys and inspections of structures such as bridges; mining operations, for volumetric analysis of materials excavated; and insurance companies, for hazard assessment and mitigation strategies when the technology proves applicable. Traditionally imagery of the earth’s surface has been collected through sensors and detectors mounted on a piloted aircraft or satellite. These missions require a large amount of planning, highly trained personnel, sensors, and fuel which make this method very expensive.  In some cases the data collected may not be accurate, or is distorted, which leads to the use of additional resources and limits their applicability. Unmanned Aerial Systems have several advantages over these techniques. UAVs can be deployed rapidly and with little planning compared to traditional missions. Through advances in technology, UAVs can carry many of the same sensors as piloted aircraft and satellites. This technology allows for safer collection methods and also reduces the amount of intense training compared to what would be needed for a piloted aircraft mission. For these reasons the use of UAVs is capable of revolutionizing the geospatial industry.

Part 1: Flight Simulator and Flight Logs

For the first part of this assignment we were to use the RealFlight 7.5 flight simulators we have here one campus. These simulators of for training in preparation for flying R/C planes and miltirotor platforms. I have used this program previous to this assignment as well as flown the real R/C machines and I am very impressed with how realistic the simulator is. As part of this weeks assignment and introduction to Unmanned Aerial System we had to fly 4 different platforms for 30 minutes each. We also were to adjust the flight conditions such as wind speed and direction to see how the platforms handle in various conditions. Below is the log of my four different platforms and flights (Figure 2). There are two flying wing platforms and two multirotor platforms. 

Figure 1
Flight log for time spent using RealFlight Simulator.

The first aircraft I used was the Hexacopter 780 (Figure 2). This is a 6 rotor aircraft with many mode options that make it much easier to fly. This aircraft is equipped with a GPS unit and RTL, self level mode and  loiter mode. The GPS mode allows you to flip a switch and have the aircraft fly along a predetermined flight path. This allows you to fly a very accurate grid pattern which is very important in real life applications. Another part of the GPS is RTL feature mode or return to launch where it will take over in autopilot and fly back to the launch point where it automatically lands itself. The self level mode makes flying easier because it always keeps the aircraft upright and very stable. If you were in acrobat mode you would be able to tilt as far as you wanted in any direction allowing you to do flips which are very difficult to control for novice pilots. Another nice feature of this aircraft is the loiter or altitude hold feature. This allows you to flip a switch and have the aircraft stop at that height. If for some reason you are falling at a very fast rate and can not slow the descent, placing the aircraft in loiter will take over and stop the descent. The altitude hold keeps the aircraft the same height off of the ground as you fly which is very handy when taking pictures and needing them to all be the same resolution. These hexacopter platforms are very stable and smooth operating. The other multirotor platform I flew was the Octocopter 1000. This aricraft was very similar to the hexacoptor. It also is very stable. Both of these platforms have a greater ability to carry instruments and sensors than other smaller platforms. They are also very maneuverable. You can move in any direction with this type of platform unlike a flying wing where you always have to be moving forward. This allows for fitting into tighter areas and getting closer to items when taking pictures. FPV or first person view is another nice feature on this platform. With first person view there is a camera facing forward on the platform that is transmitting a live video feed to a set of video goggles or a laptop screen. This lets you see what is in front of you even if you can not see the aircraft from the ground. Slower speed gives the pilot more time to react when flying these platforms which leads to less crashes. As you can see from my flight logs I had fewer crashed with the multirotor than the flying wing platform. You can also see however that sometimes the autopilot modes don't always work as you want. Knowing how to fly these manually and not rely on autopilot all the time is key to being a good pilot.

There are some drawbacks to these platforms. One is that the more rotors you have the faster the battery dies and the shorter your flights will be. Also there is no glide option with these like there is with the flying wing platforms where you can turn off the rotors to conserve battery and glide on the wind. Another disadvantage is the fact that you can move in any direction. Sometimes if you lose orientation of the aircraft and can't tell what is forward you can end up flying sideways into trees and such.

Figure 2
Hexacopter

Figure 3
Octocopter

The 3rd aircraft I used was the AR-6 Endeavor (Figure 4). This is a flying wing platform. It was extremely maneuverable and flew extremely fast. It didn't have any fancy features like the mulitrotor platforms did so it was completely manually operated. When I turned up the wind speed this plane got tossed around quite a bit and was harder to maneuver which I why I flew into a crane and crashed. The other flying wing aircraft I flew was an Harrier (Figure 5). Like the first aircraft it is very maneuverable, easy to fly and fast. When I increased the wind this aircraft reformed better than the other fixed wing but it still was a bit harder to control than the multirotors were in wind. Platfoms like these are best for when you need to cover a very large area in a short amount of time. They are much faster moving than multirotors and also have the ability to stay in the air much longer. However without all the fancy modes and features that the multirotor platforms have they can be less stable and harder to fly for novice pilots. This instability causes problems in real life too when trying to gather imagery. These platforms are harder to launch than multirotor platforms as well. With a multirotor you can set it anywhere and take off vertically. With flying wing aircraft you have to throw or propel them forward some how to get them into the air. Landing these vehicles is also more of a challenge. I had more trouble with these aircraft as I expected I would. They are much more sensitive to flying conditions as well as movements of the joystick. 

Figure 4 Endeavor

Figure 5 Harrier

   

  

Overall I found the multirotor platforms to be easier to fly and maneuver. From previous experience I figured this would be the case but all of these platforms handles differently so you never know. Adding and adjusting the flight conditions definitely makes flying more challenging. Again no matter what aircraft you are flying you need to know how to manually fly the aircraft. Auto pilot does not always function properly.

Part 2: Scenarios

1.  An atmospheric chemist is looking to place an ozone monitor, and other meteorological instruments onboard a UAS. She wants to put this over Lake Michigan, and would like to have this platform up as long as possible, and out several miles if she can.

For this scenario I would suggest the use of a flying wing platform. You are going to want to use a larger aircraft with a wing span of approx. 2 meters. This larger surface area on the wings will allow for a longer time in the air because of increased uplift on the wings. This increased uplift will also allow for an increased weight limit so the use of multiple sensors on the aircraft should not be a problem. You will want to make sure that there is a breeze of 10 to 15 MPH winds in order to increase the gliding capability and reduce battery use, maximizing time in the air. At times you will not be able to see the aircraft from where you are piloting it, therefore you will want to install a first person view camera on the nose of the aircraft pointed slightly downwards. This will allow you to see what is in front of the aircraft at all times even if line of site from the ground is cut off. In order to do this you will need to install video transmitters with a range of at least 5 miles. In order to ensure that you do not lose control of the aircraft you are also going to want to use a higher frequency and power controller good up to at least 6 miles. As a precaution I would also install a GPS tracker on the plane in case your line of site is cut off and your FPV does not work for some reason. That GPS tracker would allow you to at least direct the plane back to your location or recovery in the event of a crash. For launching the aircraft you will need a bungy cord launching station this plane will be too big to launch by hand. Once the plane is in the air I would advise that you control it from a watercraft on the lake. This increases your chances of being able to see the aircraft at all times and it also reduces the chance of losing signal of the FPV or the aircraft itself. I would advise the installation of an altimeter to aid with staying at a consistent altitude and suggest an altitude of approx. 75 meters. This will give you more accurate meteorological readings because the effects of the large water body will be reduced at that height. It will also give you a more steady wind flow which you can use to create uplift and keep your aircraft in the air longer. Try to keep the nose of the plane into the wind and do not fly across the wind because this could cause the aircraft to role causing loss of control. If you follow these suggestions you should achieve your goal and be able to collect a large amount of data. Based on the above criteria I suggest using a FE RVJet Aerobot. It has a large wing span, is light weight, has a large area for batteries sensors and other payload items and can be quickly set up and deployed. This item is a bit pricey coming in at about 3,000 dollars but it is capable of doing everything you need it to.

2. 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.

For this scenario I would suggest the use of a multirotor platform. You are going to need an aircraft that is capable of hovering in close proximity to power lines and towers and that is also very maneuverable and can fit into tight spaces. It needs to be stable and capable of carrying multiple cameras. You should have a first person view camera mounted to the front to aid in piloting the aircraft. You also will want a camera mounted to a gimbal which you can rotate up down left and right to ensure all needed pictures can be taken. Installing GPS tracker and an altimeter are also highly necessary. The altimeter will allow you do altitude hold which will greatly aid in stability of the aircraft  when taking photos. In order to use these features you are going to half to have autopilot technology on the aircraft. When trying to figure out the best way to get the supplies to the towers I would use the same platform. Using the camera on the gimbal you can take aerial photos to look for efficient routes to the towers. In order to do this I would suggest using the autopilot technology with a flight path planning program. This will assure that the flight path is straight and the resolution of the images is consistent through use of the altimeter. I would suggest flying at an altitude of 100 to 150 meters to get a large area in each photo but also be able to see details like roads and the towers. Based on the above criteria I suggest using a Turbo Ace MATRIX. It gives you this agility and maneuverability needed to inspect the towers and lines while also giving the stability and range to take good quality aerial photos for finding paths to the towers. Priced at around 3,000 dollars this is a very reasonable alternative to what you are currently paying to fly helicopter to inspect your lines. 

    Conclusion

     UAVs are very versatile and the options of what kind you can build are endless. As seen in these two scenarios the uses for UAV technology are ever expanding and very diverse. This whole exercise is both part 1 and 2 are very important when trying to understand UAVs. By seeing the different behaviors of the platforms in the flight simulator and coming up with a list of positives and negatives of each we are able to make educated decisions on the various scenarios we were presented with in part two. This is great activity to get the students to not only learn something new but to be able to apply that knowledge to real life situations. Some of the students may end up working in this field of study once they are done here at UWEC, this exercise is a little taste and a good intro to what they may work with on a day to day basis. 

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