CDR template revised Ver 3.1.1 presentation

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Team BExplorer

MACE35120 CDR Outline Version 3.1.1

MACE31520 Design 3 CDR: Team B (Explorer)

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Presentation Outline

Presenter: Arya Dash MACE31520 Design 3 CDR: Team B (Explorer)

1. Introduction – Arya Dash1.1 Presentation Outline………………………………………………….2

2. Systems Overview – Arya Dash2.1 Mission Summary……………………………………………….……..102.2 System Requirement Summary………………………………….…..112.3 System Level Configuration Trade & Selection……………………12 2.4 System Concept of Operations………………………………...……14 2.5 Physical Layout………………………………………………………..162.6 Balloon Compatibility…………………………………………...……..21

3. Sensor Subsystem Design – Arya Dash3.1 Sensor Subsystem Overview…………………………………………24

3MACE31520 Design 3 CDR: Team B (Explorer)

4. Descent Control Design – Arya Dash4.1 Descent Control Overview………………………………………….274.2 Descent Rate Estimates……………………………………………294.3 Safety Case………………………………………………………….30

5. Structural Subsystem Design – Arya Dash5.1 Structural Subsystem Overview……………………………………325.2 Mass Budget…………………………………………………………41

Presenter: Arya Dash


6. Communications & Data Handling Subsystem Design –Siddharth Mundeja6.1 CDH Overview……………………………………………………….436.2 Frequency Selection……………………...………………………...466.3 Antenna Trade & Selections ………………………………………476.4 Antenna Choice……………..………………………………………496.5 Radio Configuration…………………………………………………50

7. Electrical Power Subsystem Design – Siddharth Mundeja7.1 EPS Overview………………………………………………………..537.2 Electrical Block Diagram…………………………………....………58



8. Flight Software Design- Bagrat Rashoyan8.1 FSW Overview……………………………………………………………….648.2 FSW Architecture…………………………………....................................658.3 System FSW State Diagram…………………………………….………….68

9. Ground Control System Design – Bagrat Rashoyan9.1 GCS Overview…………………………………………………….………….709.2 GCS Antenna System……………………………………………….……....729.3 Antenna Distance Link…………………………………………….…………739.4 GCS Software……………………………………………………….………..74

10. System Integration and Test – Stephen Choi10.1 System Integration and Test Overview……………………….….……….76

12. Management – Stephen Choi12.1 System Budget…………………………………………………….....……..10012.2 Conclusions……………………………………………………….…………112


MACE31520 Design 3 CDR: Team B (Explorer) 9

Systems Overview

Arya Dash

10

Mission Summary


Mission Objectives: Primary Rationale: System must measure oxygen level: Data can be

used for biological studies of phenomena such as ‘hypoxia’ and ‘cyanosis’ or ‘altitude’ training of athletes

Auxiliary:• Safety first!!• System must satisfy CAA Small Balloon Requirements- All up system

below 2m

System Requirement Summary

11MACE31520 Design 3 CDR: Team B (Explorer)Presenter: Arya Dash

MAJOR ITEMS OF NON-COMPLIANCE: Altitude of 7500 m as opposed to 9100 m.

Rationale: Biological studies are of interest in the lower atmosphereBenefits:– Better Ascent performance: reduced ‘Lift’ requirements– Enhanced Power Consumption: Reduced flight time– Improved Sensor Performance: Warmer temperatures– Better T/W Ratio

Solar Sensor Oxygen Sensor No Back Up Power Source

12

System Level Configuration Trade & Selection

MACE31520 Design 3 CDR: Team B (Explorer)Presenter: Arya Dash

• MECHANICAL SUBSYSTEM changes since PDR:

PDR LEVEL:• Did not conform with the CAA

Small Balloon Requirements• Unsafe and unreliable: Hook

interfaces

CDR LEVEL:• Fully conforms with CAA Small

balloon Requirements• Improved Reliability: Knots and

fewer interface connections


System Level Configuration Trade & Selection

ELECTRONIC SUBSYSTEM: Selection of Components and Tradeoff

Component PDR Selection

Major Reasons CDR Selection

Advantages Trade-off

Microcontroller Arduino Due

Compatibility issues with GSM and Oxygen Sensors

Link-it one • Integrated GSM • Oxygen

Sensor-‘Easy to integrate’

Power

GPS ADAFRUIT Poor Compatibility with Link-it One

MediaTech MT3332

Highly compatible Placement Flexibility (Short wire length)

Arrangement of temperature sensor and altimeter

On side surfaces

• Cross winds• Entangling

issues

At the bottom protected by a grove

• No interference from cross winds and mainstream flow

• No tangling issues

Manufacturing



System Concept of Operations


• Launch and Descent

14

Ground Station

Launch,GSM not activated

Balloon Burst

>7500m Parachute Deployment

GSM activated,Payload

Touchdown,System

recovery.

Sensors record data, data

stored in SD card,

Telemetry packet transmit data to Ground

Station

Physical Layout

Ascent Mode: Descent Mode:

16Presenter: Arya Dash MACE31520 Design 3 CDR: Team B (Explorer)


Physical Layout


Placement of major components:


Physical Layout


Placement of major components:

21

Balloon Compatibility

MACE31520 Design 3 CDR: Team B (Explorer)Presenter: Arya Dash

Balloon Payload Compatibility Analysis using Non-Dimensional Studies:• Key Parameter for aerodynamic performance: T/W Ratio• Min. T/W requirement is also influenced by required ‘ascent rate’

Balloon Compatibility

22Presenter: Arya Dash MACE31520 Design 3 CDR: Team B (Explorer)

Physics

Lift due to buoyancy

Mass of (payload+balloon) x g

Drag

Force due to buoyancyM- Total massg- Acceleration due to gravity- Force due to drag- Density of Helium v-velocity of system

S- cross section area of balloon


Sensor Subsystem Design

Arya Dash

24

Sensor Subsystem Overview


GPSModel No: MT3332

This sensor will be used to get values for latitude, longitude and altitude

Grove Gas Oxygen Sensor

Model No: O2This Sensor is used to calculate main sensor subsystem requirement, that is oxygen.

Temperature SensorModel No: DS18B20

The System will use this sensor in order to measure internal temperature.

Voltage SensorModel :Micro HKPilot Mega

PDBThis Sensor is used to take voltage reading for battery throughout the flight. .

AltimeterModel No: BMP180

Our System uses this sensor to get values for altitude, external temperature and pressure.


Descent Control Design

Arya Dash


Descent Rate Estimates

20 40 60 80 100

120

0

4

8

12

16

Descent velocity Vs. Parachute Diameter

Descent velocity (m/s)

Diameter (cm)

Desc

ent V

eloc

ity (m

/s)

Ideal Range

Design Point

• Partial deployment of parachute reduces projected surface area and drag coefficient due to shape deformation i.e. Cd*S reduces.



Safety Case

4.47

4.71

5.00

5.34

5.77

6.32

7.07

8.16

9.99

11.30

12.00

05

1015202530354045

Kinetic energy Vs. Impact velocity

Kinetic energyThreshold

Impact velocity (m/s)

Kine

tic e

nerg

y (J

)

34J

40J

• According to the the document produced by Monash University, ‘Human injury model for small unmanned aircraft impacts,2013’ kinetic energy for impact above 40 J is considered dangerous to humans.

• Max attainable kinetic energy is 34 Joules at all measure of undeployed parachute which is below the threshold kinetic energy of 40 J.



Mechanical Subsystem Design

Arya Dash

Mechanical Subsystem overview

Structure A newly designed light weight case to house the sensors and other electrical components

Material Built from polystyrene foam blocks.

Assembly The structure is easily assembled from 2 main sections; the main housing part and the lid.

Interface The parachute is secured to the payload box with a mounting plate. The Balloon is connected to the payload by a cable that goes through a hole at the top of the parachute and the mounting plates.

32MACE31520 Design 3 CDR: Team B (Explorer)Presenter: Arya Dash


Mass Budget

483 g, 96.6%

17 g, 3.4%

All Up Mass

Measured Margin

All Up Mass 483 gramsMax. Allowed 500 grams



Communication and Data Handling (CDH) Subsystem Design

Siddharth Mundeja


CDH Overview

Presenter: Siddharth Mundeja

LinkIt-One [with integrated GSM & GPS]

3DR Transceiver

433 Mhz Yagi Antenna

Connected via Tx & Rx Pin

Connected via SMA Connector using adapter

Connected via USB

Sends a text with GPS data when below 1000m

3DR Transceiver

Ground Station Computer [with GCS Software]

Data From Sensors

• Continuous data transmission

• 10mW• 100% duty cycle• 434.20 MHz • 25 kHz channel

Ground Control System


CDH Requirements

433.05

434.2 434.79

100% 1 mW; no channeling

100% 10 mW; 25kHz channels

10% 10 mW; no channeling

Ofcom specifications for 433 MHz unlicensed Short Range Devices (SDRs)Legal Requirements.

Selected


• ~ 800 bits per second• Low power consumption

• Omnidirectional Transmission• Low power consumption


Antenna Trade & Selection

Trade Parameters Monopole Antenna Loop Antenna Helical Antenna

Criteria (Weightings %) Score

Weighted Score

Score

Weighted Score

Score

Weighted Score

Range (50) 9 4.5 6 3 3 1.5

Ease of De-tuning (5) 9 0.45 5 0.25 3 0.15

Gain (5) 8 0.4 5 0.25 5 0.25

Size (10) 9 0.9 4 0.4 2 0.2

Weight (20) 9 1.8 6 1.2 3 0.6

Cost (10) 7 0.7 9 0.9 5 0.5

Total Weighted Score 8.75 6 3.2

Selected Antenna: Monopole Antenna • Best range• The whip antenna mitigates a mechanical construction that the helical antenna

and the loop antenna offers.• With the sacrifice of cost, the best performance is delivered.

Higher is better



Antenna Choice

• Quarter wave Monopole Antenna

• Vertically Polarised

• 2dBi gain

Radiation Pattern: Doughnut Shaped

3DR Radio with Antenna

Remote module Antenna



Radio Configuration

• 3DR Digital telemetry radio

• Custom data packet


• Radio configuration (NETID, baud, etc.) set via “Mission Planner” GUI”

• Configuring Net ID for pairing and ensuring not receiving alien data

• Setting min max frequency for spectrum hoping(within license free zone)


Electrical Power Subsystem (EPS) Design

Siddharth Mundeja


EPS Overview

Made by: Ola Majasan

Component Diagram

• Battery: 3 x Varta (1x1.2V) 500mAh NiMH Rechargeable Coin Cell Battery

Microcontroller• Acts as a node.• Distributes current

to sensors & Radio

Micro HKPilot Mega PDB• Measures the

Voltage across the battery. Value reported to GCS.

Sensor and Radio

• Sensors 3.3 V• Radio 5.0 V

Main Supply Battery (3.6 V)

58

Electrical Block Diagram

Battery

Radio Module, Supply with 5 V

Altimeter, Supply with 3.3V

Oxygen Sensor, Supply with 5V

Grey Arrows : These indicate the direction of flow of information throughout the circuit.

Blue Arrows : These indicate the direction of flow of power throughout the circuit.

Temperature Sensor, Supply with 3.3V

Current/Voltage Sensor


GPS antenna, Supply with 3.3V

Made by: Ola Majasan


Flight Software (FSW) Design

Bagrat Rashoyan


FSW Overview

Initialising Sensors(at start/reboot)

Loop: Data acquisition

(2 second sleep)

Transmit Store

Data Flow• Programming language – C/C++ with wrappers

• MCU Operating System – None

• Programming Environment – Arduino

• Using libraries supplied by sensor vendors

• Data stored on SD card

• Consumes an average of 115 mAh (90 when at sleep, 140 when transmitting) available 500 mAh [Voltmeter tested]

Presenter: Bagrat Rashoyan

FSW Architecture

65MACE31520 Design 3 CDR: Team B (Explorer)Presenter: Name goes here

ARCHITECTURE

SENSORS

MCU

DATA LOGGINGRADIO

DATA RECEIVEDDATA TRANSMIT

GSM MODULE


Declare variables Setup(){ Initialize sensors}

Loop(){ Get Senor Data Transmit Store Sleep for 2 seconds}

"#,teamID,packetNo,packetTime,lat,lon,alt,satNo,baroH,press,extTemp,intTemp,vol,MD5"


Ground Control System (GCS) Design

Bagrat Rashoyan

70

GCS Overview

LinkIt-One [with integrated GSM & GPS]

3DR Transceiver

433 Mhz Yagi Antenna

Connected via Tx & Rx Pin

Connected via SMA Connector using adapter

Connected via USB

Sends a text with GPS data when below 1000m

3DR Transceiver

Ground Station Computer [with GCS Software]

Data From Sensors

• Continuous data transmission

• 10mW• 100% duty cycle• 434.40 MHz • 25 kHz channel

Ground Control System

Presenter: Bagrat Rashoyan MACE31520 Design 3 CDR: Team B (Explorer)


GCS Antenna System

Presenter: Kelvin Kan 72

Radius =1 meter

Antenna in clear line of Sight of the remote module manually adjusted to pint towards the module continuously.

Antenna 1 m clear of any objects to prevent signal bouncing.

Lightening arrestor to protect the system and operator

2 m

Masted 2m above the ground on a non-conducting mast

Antenna set at the highest possible position at the launch site.

MACE31520 Design 3 CDR: Team B (Explorer)Presenter: Bagrat Rashoyan


Antenna Distance Link

The following equation gives a theoretical range of the yagi antenna communicating with the system monopole antenna.

R = Transmission Distance in kmf = FrequencyPt= is the Tx power for the device that will be transmitting data Gt= is the Tx antenna gain, the antenna gain of the antenna on the transmitting device.Pr= is the Rx sensitivity of the device receiving data.Gr= is the Rx antenna gain, the antenna gain of the antenna on the receiving device.c = speed of light

Tx power = 10 dBmTx antenna gain = 3.3 dBi

Rx sensitivity = -118 dBmRx antenna gain = 13 dBi

Frequency = 434.2 MHz The distance link is estimated to be 20.8 km

𝑹=√ 𝑷𝑻 𝑮𝑻 𝑮𝑹𝒄𝟐

𝑷𝑹× 𝟏𝟒𝝅 𝒇


GCS Software

• Custom GUI software designed Using Qt Creator (C++)• Data received from 3DR radio through USB com port, parsed and

displayed on relevant LCDs

MACE31520 Design 3 CDR: Team B (Explorer) 74Presenter: Bagrat Rashoyan


System Integration and Test

Stephen Choi


System Integration and Test Overview

Presenter: Stephen Choi

Test Title Purpose Test Set up Test Inputs

Successful criteria

Predicted Result and

basis

Recorded Result

Actions Required Order

Mechanical SubsystemPayload box drop test

Survivability of structure and components are protected during impact.

Container with all components mounted in the container and suspended from high ledge

Release of container

• Accelerating force inside the container are not too large

• Visual inspection of acceptable damage

All components remain in working condition after impact.

Structure remain intact and electric components remained functional

• Additional Shock absorbing padding

　 1

Parachute deployment test

Successful deployment of decent control mechanism during freefall

Parachute and container assembled in decent configuration.

Release of container with parachute

• Successful deployment of parachute

Successful deployment of parachute

　 N/A • Alternate nylon cables and pre-prepped loops

• Pre-manufactured parachute

　 3

Knot Connections

Ensure Knots do not come undone or cut during operation

Using a force meter pull one end of the cable and secure the other end using knot.

Increase force on cables

• Retained integrity of knots

Knots will be intact

N/A 　 2



Test Title Purpose Test Set up Test Inputs Successful criteria


basis

Recorded Result

Actions Required

Order

Electrical SubsystemElectrical Connection test

Integrity of electrical connections after soldering and placement

Electrical components soldered

Multimeter testing

• Voltage across components

• No noise

Voltage and current readings shows a closed circuit

All electrical components were connected

　 4

Battery Endurance Test

Show the available run time of the power pack

Connect all electrical components and leave the system to operate for a specified period.

Timer • Can at least power system for four hours

System can operate for over four hours

Total Run-time: 6 hours

　 5

Cold Temperature Tests

Effects of temperature on the electrical components

Payload box with electrical components connected

Cold box to create environment

• Electronics still functional and report sensible values

Electronics still functions as intended

Tested for -20 degrees　

　 6




Test Title Purpose Test Set up Test Inputs Successful criteria


basis

Recorded Result

Actions Required

Order

CDH SubsystemRadio Reliability Test in Urban Environment

Radio and Antenna communic-ation reliability

GCS and completed payload box set at >1km apart

GCS and CDH software

Continues to communicate and receive data >1km

Successful communication with some interruptions

Successful communi-cation with some interference

　　 7

Data Storage Test all required data can be reliably stored on microSD card

Insert microSD into LinkIt One and start sensor recordings

Non-corrupt data could be retrieved from microSD

Useful data could be obtained

No issues encountered

　　 8



Mission Operations & Analysis

Stephen Choi


Management

Stephen Choi

100

System Budget – Other Costs


Components Model Quantity Cost (£) Price Definition

Battery Varta 3.6V NiMH coin cell

1 4.90 Actual

Microprocessor Arduino Due 1 34.27 Actual

Temperature sensor DS18B20 1 3.93 Actual

Mounting plate 4MP1212 2 16.14 Actual

Parachute - - 1 3.00 Budgeted

Polystyrene Box - - 2 5.00 Budgeted

Subtotal 67.24

Prototype & Testing

LabourComponents Model Quantity Cost (£) Price Definition

Human labour Undergraduate 1200 hours 18000 Approximation

Subtotal 18000


101

System Budget – Total Cost


Budget Type Sub-total Cost (£)

Sensor Subsystem 83.88

Electrical Power Subsystem 27.13

Communications and Data Handling Subsystem 140.41

Structural 30.50

Ground Control System 172.36

Prototype & Testing 67.24

Overall Total 521.52



Conclusions


Major accomplishments:• Re-designed system to comply with CAA small balloon requirement• Reduced weight to below 500g• Sensors are working• Communications are working• Mitigation by producing our own payload box and parachute• Launch day schedule and operations manual• Budget estimated

Major unfinished work:• Oxygen sensors need to be purchased• Solar panel needs to be purchased• Oxygen and solar flux sensors need to be programmed and calibrated• Some tests to be carried out

Why we are ready to proceed to flight readiness review:• System is designed and built, with tests done showing a good performance

and compliance to most requirements. Non-compliances are explained.

Documents

CDR template revised Ver 3.1.1 presentation