P19123: Lockheed Amelia Drone
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Detailed Design

Table of Contents

Team Vision for Detailed Design Phase

PLANNED

ACCOMPLISHED

Phase IV: Accomplishments

Phase IV: Accomplishments

AREAS OF CONCERN

Progress Report

Progress Report

Progress Report

Problem Statement and Project Summary

System Overview

Amelia Project Diagram

Amelia Project Diagram

 Hardware Diagram

Hardware Diagram

Specification Tracker

Specification Tracker

Hardware / Subsystem Test

Test Rundown Page 1

Test Rundown Page 1

Test Rundown Page 2

Test Rundown Page 2

To view the whole test document: Hardware Test Plans

Heat Transfer Analysis

Per the instructions of Dr. Stevens, the camera is the limiting factor and modeled as a fin where the mounting area is treated as being adiabatic. Below are the conditions analyzed:
Camera Heat Model Schematic

Camera Heat Model Schematic

CONCLUSION

For the full analysis: Heat Transfer Analysis

Transmission Analysis

Transmission throughput flowchart

Transmission throughput flowchart

We want to transmit 4K video live from the Ricoh Theta V to the base station. According to the Ricoh Theta V specifications listed on the Ricoh website, the Ricoh Theta V livestreams H.264 encoded 39 FPS 4K video at 120 Mbps (megabits per second) using the USB cable. We intend to use this interface method for our application.

Between the radio transmitter we intend to use and the Ricoh Theta V sits a USB OTG to ethernet adapter. This is required to livestream video using the Ricoh Theta V’s Android based “plugin” system, since no developers seem to have been able to get access to the USB host controls on the Ricoh Theta V. This adapter makes the USB connection appear to be an ethernet connection to the Android operating system on the Ricoh Theta V. USB OTG is a USB 2.0 based connection standard. While USB 2.0 had a theoretical 480 Mbps throughput, in real world scenarios (as a result of bus access constraints) USB 2.0 speeds are closer to 280 Mbps. At half of the expected USB 2.0 throughput, we should still be able to transmit our 120 Mbps video stream. The ethernet cable from the ethernet adapter is then connected directly to the radio transmitter.

We intend to use a PtP (point to point) WiFi / radio connection to stream our encoded video from the drone to the base station. We intend to use the Ubiquiti Nanostation 5AC as the transmitter mounted on the drone. According to the NanoStation 5AC specifications listed in the User Guide the NanoStation 5AC has a realistic throughput of 450 Mbps, and a range of 15 km when using the highest frequencies and 256 QAM modulation. The NanoStation was selected as the transmitter since it has a relatively large receiving cone, suitable for the vibrations on a UAV platform. If the built in antenna underperforms, we could always purchase a high gain, omni-directional antenna for the transmitter.

On the ground station we intend to complete the PtP link using a NanoBeam 5AC Gen2. According to the specifications in the User Guide, the NanoBeam 5AC Gen2 has a range of 15 km and a throughput of 450 Mbps. Compared to the NanoStation 5AC, it has a narrower FOV. This is fine for a ground-based receiver since we can accurately aim the NanoBeam and don’t need to worry about vibrations.

Even at half of Ubiquiti’s “real world” throughput of 450 Mbps, there should be no throughput issues transmitting the Ricoh Theta V’s 120 Mbps 4K video feed. The 120 Mbps video is fed through the USB to ethernet adapter to the NanoStation, which can reportedly beam data 15 km at 450 Mpbs. Then at the base station the NanoBeam communicates with the NanoStation, and has similar specifications. Our engineering requirements only require us to transmit our video 0.25 miles, or 0.4 km, which should allow our throughput to approach the advertised NanoStation / NanoBeam throughput rates. The caveats are there may be issues regarding range and signal quality given the test environment and the alignment of the NanoBeam and NanoStation. Fortunately these issues can be alleviated by purchasing new antennas and by consulting SMEs.

NanoStation 5AC Gain Diagrams

NanoStation 5AC Gain Diagrams

The above gain diagrams are provided by Ubiquiti and characterize the gain of the NanoStation 5AC that will be mounted on the drone. As shown by the graphs, signal reception directly behind the transmitter is poor or nonexistent. We will perform testing and analysis to make sure the transmission hardware is properly oriented for maximum signal throughput. In the event that we receive a budget increase and the testing yields inadequate signal reception with the NanoStation 5AC, we could opt to use an omnidirectional antenna. The gain diagrams for the omnidirectional antenna we would use can be seen below.

Ubiquiti AMO5G-10 Gain Diagrams

Ubiquiti AMO5G-10 Gain Diagrams

Software Design and Benchmarking

PC Spec Test

PC Spec Test

Local video playback software demo

Local video playback software demo

Software Diagram

Software Diagram

Weight Analysis

To track the payload we are adding to our drone as well as the overall weight, a chart containing the mass of every component on the drone was developed. This allows us to see a conservative estimate of the total weight of our drone, and ensure that it does not exceed the maximum payload specification of our chosen drone.

Payload Overview Chart

Payload Overview Chart

Mounting Bolt Calculations

The mounting holes on the DJI S900 drone that we purchased are M1.6x35. Due to the small size of these bolts, it was relevant to perform calculations to ensure they do not fail under shear stress during the worst case flying conditions. After conducting the calculations, it was discovered that the bolts will not fail under the worst case loading by a very large margin.

Mounting Bolt Calculations

Mounting Bolt Calculations

Center of Gravity

Since a drone is a very lightweight aircraft, changes around its center of gravity can have significant effects on the way it is able to perform. We saw this as a relevant future concern since we will be adding extra payload to our drone. We decided to seek help from a subject matter expert in flight dynamics, Dr. Crassidis. To ensure the center of gravity does not change very much, the payload should create as little of a moment around the drone's center axis as possible. To account for this, the harness was designed with modular mounting slots.
Center of Gravity Calculations

Center of Gravity Calculations

Subject Matter Experts

We encountered various topics and issues during the design process that we did not have a lot of knowledge about. For these design hurdles, we sought out subject matter experts in various fields to assist with our design and overall understanding of the hardware we would need and the system we were dealing with. The professors that we met with were Dr. Indovina who is an SME on wireless transmission, Dr. Steven's who is an SME on heat transfer, and with Dr. Crassidis, who is an SME in aviation dynamics and controls.
SME Meeting Takeaways

SME Meeting Takeaways

Drawings

To thoroughly document all of the hardware that we will be using for this project, drawings for each piece of equipment have been made. These drawings document important specifications for each item, give a visual representation of the parts that will be used, and detail the necessary specifications needed for each piece of hardware.

Drone Drawing

Drone Drawing

Drone Assembly Drawing

Drone Assembly Drawing

Hardware Mount Drawing

Hardware Mount Drawing

Mounting Cover Drawing

Mounting Cover Drawing

Camera Drawing

Camera Drawing

USB to Ethernet Adapter Drawing

USB to Ethernet Adapter Drawing

Nanostation5 Transmitter Drawing

Nanostation5 Transmitter Drawing

Receiver Drawing

Receiver Drawing

POE Adapter Drawing

POE Adapter Drawing

Portable Charger Drawing

Portable Charger Drawing

Oculus Rift Headset Drawing

Oculus Rift Headset Drawing

Oculus Sensor Drawing

Oculus Sensor Drawing

Acer 5 Laptop Drawing

Acer 5 Laptop Drawing

Bill of Material (BOM) & Budget

With the current budget we can achieve the original engineering requirements, but with some limitation that limit the scope and applicability of the project. To be clear, with the current budget we can achieve the primary engineering goals: 0.25 mile range, 20 minutes flight time, full 360 degree video stream, interactive VR experience.

However, there are limitations to the current system, as well as budget related impediments that could have a large impact on delivering a fully functional and reliable system by the end of next semester.

All of these issues can be remedied with a budget increase. Our current budget does not give us the leeway for failures or redesigns, and requires us compromising on certain objectives. It also greatly slows down our development process, meaning that the resulting system will be less polished. A budget increase would allow us to solve the issues in the following ways:

While attempting to satisfy our budget constraints, a few steps were taken to minimize costs. Rather than using DJI’s N3 flight controller, we are using a more customizable and open source solution by combining a PixHawk 4 Flight Controller and a PixHawk 4 Neo-8MN GPS. This measure saved approximately $100. We are also using a relatively cheap radio controller (the FrSky Taranis Q X7). For the transmission system there are alternative companies that build backhaul networking hardware similar to Ubiquiti, but they are all comparatively priced, and we have a local SME that explicitly recommended using Ubiquiti hardware.

Unfortunately, there are certain high-ticket items that we are unable to compromise on.

In total we are looking at a budget increase of $1250, which will allow us to deliver a fully functional product that completely delivers on the engineering requirements with a polished system. This budget also allows us to handle sudden and unexpected mishaps both covered and uncovered in our risk assessment documents, and will also mean we can iterate and test faster.

Final BOM without budget increase

Final BOM without budget increase

Additional items if budget is increased

Additional items if budget is increased

Test Plans

P19123 Test Validation Matrix

P19123 Test Validation Matrix

For the full document: P19123 Test Validation

Design and Flowcharts

Electronics Diagram

Electronics Diagram

Risk Assessment

Top 5 Risks

Top 5 Risks

By designing around risk items and taking active measures to minimize risks, we have largely reduced our risks to the 5 risks above.

Plans for next phase

MSD II Phase I

MSD II Phase I

MSD II Phase II

MSD II Phase II

MSD II Phase III

MSD II Phase III

MSD II Phase IV

MSD II Phase IV

MSD II Phase I: Project Plan

MSD II Phase I: Project Plan

Reflection

Phase IV: Accomplishments

Phase IV: Accomplishments


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