Telemetry System for SAE Aero Advanced Class Team Robbie McNally ECE499 Professor Spinelli

55 Pages·2016·2.25 MB·English

Telemetry System for SAE Aero Advanced Class Team

Robbie McNally

ECE499
Professor Spinelli

March 15, 2016
McNally ECE499 Design Report.docx 1

Contents
Figures and Tables ........................................................................................................................................ 3
Project Summary ........................................................................................................................................... 4
Introduction .................................................................................................................................................. 5
Background ................................................................................................................................................... 6
Design Requirements .................................................................................................................................... 9
Design Alternatives ..................................................................................................................................... 14
Proposed Design ......................................................................................................................................... 16
Data Acquisition System ......................................................................................................................... 18
First Person View System ........................................................................................................................ 23
Preliminary Design Testing ......................................................................................................................... 24
Data Acquisition System Testing ............................................................................................................. 24
MPL3115A2 Barometric Pressure Sensor Testing ............................................................................... 24
XBee Range Testing ............................................................................................................................. 25
First Person View Testing ........................................................................................................................ 25
Final Design and Implementation ............................................................................................................... 27
Components in Plane .............................................................................................................................. 27
Arduino Uno, XBee Transmitter, and Sensors .................................................................................... 27
Analog Video Transmitter – Boscam TS352 ........................................................................................ 29
Components at Ground Station .............................................................................................................. 29
XBee Receiver and Makerplot ............................................................................................................. 29
Analog Video Receiver and VirtualDub ............................................................................................... 30
Performance Results ................................................................................................................................... 31
Production Schedule ................................................................................................................................... 34
Cost Analysis ............................................................................................................................................... 36
User Manuals .............................................................................................................................................. 37
Data Acquisition System User Manual ........................................................................................................ 37
First Person View User Manual ............................................................................................................... 38
Discussion, Conclusions, and Recommendations ....................................................................................... 39
References .................................................................................................................................................. 40
Appendices .................................................................................................................................................. 42
Appendix A: Testing Results .................................................................................................................... 42
Test 1: MPL3115A2 – 10ft Test ........................................................................................................... 42
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Test 2: BMP180 – 10ft Test ................................................................................................................. 43
Test 3: MPL3115A2 – 33ft Test ........................................................................................................... 44
Test 4: Camera Field of View Test ....................................................................................................... 45
Appendix B: Calculations......................................................................................................................... 46
Data Acquisition System Current Draw Calculations .......................................................................... 46
Data Acquisition System Battery Capacity Calculations ..................................................................... 46
One or Two Battery Calculations ........................................................................................................ 47
Appendix C: Arduino Code ...................................................................................................................... 49
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Figures and Tables
Figure 1: Advanced Class Scoring Equation Page 10
Figure 2: Data Acquisition System Requirements Page 11
Figure 3: First Person View System Requirements Page 11
Figure 4: Minimum System Block Diagram Page 12
Figure 5: Ultra Micro FPV System Page 14
Figure 6: Seagull Wireless Dashboard Flight System Page 15
Figure 7: Proposed System Block Diagram Page 17
Figure 8: I2C Bus Schematic Page 21
Figure 9: Data Acquisition System with Breadboard Page 21
Figure 10: microSD Shield Prototyping Area Page 22
Figure 11: RC305 Receiver, TS352 Transmitter, and Camera Page 23
Figure 12: Video Quality at 1500ft Page 23
Figure 13: Arduino with Shields Page 27
Figure 14: MakerPlot Data from Crash Page 30
Figure 15: DAS Coax Cable Extension Page 32
Figure 16: 900MHz Duck Antenna - VNA Results Page 33
Figure 17: DAS Test Drive in Truck Page 34
Table 1: System Cost Analysis Page 36
Figure 18: MakerPlot Interface Select Page 37
Figure 19: RC305 and USB EasyCap Page 38
Table 2: MPL3115A2 Altitude Sensor Testing – 10ft Page 42
Table 3: BP180 Altitude Sensor Testing – 10ft Page 43
Table 4: MPL3115A2 Altitude Sensor Testing – 33ft Page 44
Figure 20: MPL3115A2 Measured vs Expected Elevation Page 44
Figure 21: Camera Field of View Test Page 45
Table 5: DAS Current Draw Calculations Page 46
Table 6: DAS Battery Capacity Calculations Page 46
Table 7: Separate Battery Calculations Page 47
Table 8: Combined Battery Calculations Page 48
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Project Summary
The goal of this project is to provide the Union College SAE Aero Advanced Class team with the
electrical systems and knowledge necessary to succeed in the 2016 SAE Aero Design Competition. The
two main parts of the project are the Data Acquisition System (DAS) and First Person View (FPV) system.
Each of the systems has minimum functional requirements laid out in the competition rules. Additional
components are allowed to enhance reliability or functionality but increase weight and complexity.
The data acquisition system and first person view system will be physically separate and easily
movable so that they can be easily removed for maintenance or moved into another plane. The design
will be as simple as possible to ensure reliability but must be robust enough to provide all of the data
needed in a very electronically noisy environment. In the current design the First Person View System
consists of a TS352 transmitter, RC305 receiver, and camera. The Data Acquisition System consists of an
Arduino microcontroller with an XBEE transmitter and various sensors. The first person view system
meets all of the design requirements in its current state. The current data acquisition system meets the
competition requirements but the range is not enough to meet the required factor of safety set forth by
the Union College SAE Aero Team.
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Introduction
The goal of this project is to provide the SAE Aero team with the electrical systems needed to
compete at the SAE Aero competition. The project aims to exceed the requirements for competition by
providing onboard data storage to a microSD card and airspeed data via a pitot tube mounted in the
wing. Reliability is key due to the fact that if any electrical system fails during a flight the team receives a
0 score for that round. Therefore the system must provide accurate real time data from the plane at all
times.
The goal of the advanced class competition is to build a gas powered RC plane that drops
“humanitarian aid packages” during a flight onto a target zone. The competition is scored based on how
much weight your plane can carry as well as how accurately the care package is dropped onto a bullseye
shape target zone. The plane must carry at least an altitude sensor, altitude transmitter, camera, and
video transmitter to meet the minimum competition requirements. The Data Acquisition System must
wirelessly relay altitude data from the plane to the ground and record when the package is dropped.
The First Person View System must wirelessly transmit video feed to the ground. The combination of
altitude data and camera feed will be used by a team member to determine when to drop the package
to hit the center of the target.
Reliability is a concern due to the large amount of electrical noise generated by all of the other
teams at the competition field. The systems transmitters must be powerful enough to penetrate
through the noise and might also want to feature Frequency Hopping Spread Spectrum to avoid
interference as much as possible. The electrical systems must also take up a minimal amount of space
and weigh as little as possible to keep the plane light. The remainder of this report focuses on providing
a background of the topic before listing the design requirements in detail. The focus then moves to
design alternatives and a detailed explanation of the proposed design. Some testing has already taken
place and the results along with calculations can be found in the appendices.
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Background
Wireless telemetry systems have become more popular in recent years due to advances in
technology and dropping cost. Many RC accessory manufacturers offer a telemetry system that plugs
into their radio controller and utilizes the same receiver and frequency (2.4GHz) to display data on the
controllers screen. Some manufacturers even offer systems which can display data on a smartphone
application1. These systems are plug and play and require no knowledge of electric systems or
programming. In our case, the data acquisition system can reside in the controller but the data must be
logged on the ground and when the package is dropped the ground station must be alerted. The prebuilt
systems do not have the capability to log events like the package being released so a system must be
programmed to detect the drop and produce altitude data.
First Person View systems have also become increasingly popular among RC drone and plane
pilots due to the extensive range and image clarity that newer systems provide. 5.8GHz is the most
popular frequency band used by first person view systems due to its long range and small antenna size.
Video transmitters can be analog or digital. When an analog video transmitter is nearing its maximum
range, the video becomes “snowy” and loses clarity. A digital signal will be perfectly clear until its
maximum range and then the signal will be completely lost and the screen will go black. The other main
difference between video transmitters and receive pairs is the encoding scheme. The two encoding
schemes used in FPV transmission are National Television System Committee (NTSC) and Phase
Alternation by Line (PAL). Each scheme uses a slightly different aspect ratio and frame rate and PAL
offers automated color correction while NTSC does not. NTSC is mostly used in the US and PAL is used

1 "Telemetry." Spektrum RC. Spektrum. Web. 17 Nov. 2015.
<https://www.spektrumrc.com/Technology/Telemetry.aspx>.
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mainly in the UK and Sweden2. The transmitter and receiver must both support the encoding scheme
used by the camera but many systems are beginning to support both encoding schemes.
Due to the sometimes violent nature of airplane flights, the project must be able to survive
small crashes and hard landings. The high performance gas engine which will power the plane causes
the plane to vibrate. The electrical system connections must be robust enough to survive the normal
vibrations of the running engine. In case of an emergency if the entire plane and electrical systems are
ruined, the systems must be able to be reproduced in a timely manner. This means using off the shelf
parts that are easy to obtain and having the knowledge and tools to be able to quickly construct a
backup system. The camera system which will be used is one of the most popular models online; TS352
transmitter and RC305 receiver. These components are readily available at a multitude of online
retailers and can use any 12V FOV camera. The data acquisition system will be made up of a
microcontroller, transmitter, and various sensors. All of these parts are general purpose electronics and
can be bought online. The backbone code of the data acquisition system can be uploaded to a new
microcontroller in minutes to deploy a new system if necessary.
Safety is a large concern for flying large gas powered remote airplanes. The propellers are
essentially giant fans with knives on them and the planes are large and heavy. The project must not
diminish the overall safety of the plane. The Lithium Polymer batteries used in the plane must be placed
in fireproof bags and properly ventilated for heat. The external reset switch must also be mounted at
least 12” from the propeller to ensure it can safely be triggered without being near the moving
propeller.

2 Baltz, Aaron. "NTSC vs PAL: What Are They and Which One Do I Use?" Discovery Center Blog. Corel, 21 Aug. 2014.
Web. 17 Nov. 2015. <http://learn.corel.com/news/ntsc-vs-pal-what-are-they-and-which-to-use/>.
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Last year the SAE Aero team had its first two electrical engineers; Joey Laub and Ervin Meneses.
Ervin worked on optimizing the electrical engine while Joey created a black box for the plane. Joey’s
system captured altitude and airspeed data on the plane and logged it to an EEPROM chip. After the
plane landed the chip was removed and connected to a computer where the data was read and
processed by MatLab. The project will be an improvement on last year’s system by allowing wireless
transmission of data from the plane to the ground.
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Design Requirements
The design requirements for this project are imposed by the 2016 SAE Aero Competition Rules.
This project is focused on competing in the advanced class so only those rules and scoring formulas
apply. The Union College SAE Aero advanced class team must build an RC plane which carries a static
payload as well as a droppable “humanitarian care package” (beanbag with a streamer on it). The plane
must feature a video transmitter and a way to transmit altitude data to the ground station. During
competition, a team member will watch the video feed and telemetry data to determine when to
release the payload so it lands as close to the target as possible. The scoring formula for the advanced
class competition is shown below in figure 13. As seen in figure 1 from section 8.17 of the SAE Design
Rules, the scoring is based on the planes static payload multiplied by a “Zone Multiplier” ranging from 0
to 1 depending on how close the dropped package was to the target.

3 SAE Aero Design. "2016 Collegiate Design Series." 35. SAE International (2016). Web. 18 Nov. 2015.
<https://www.saeaerodesign.com/content/2016_ADR_10292015_REV5_FINAL.pdf>.