Mission Statement and Objectives Design Requirements Functional • Log radiation and corresponding altitude for duration of flight (up to 90,000 feet and back) • Store data on non-volatile memory • Provide power for duration of flight plus one hour set up and one hour for recovery (4 hours minimum) • Indicate the unit is powered on • Indicate system is running properly • Ensure system is both water-resistant and buoyant • Provide internal fire resistance • Provide internal temperature regulation • Ensure system will operate within temperature range and withstand forces of launch, ascent, balloon breaking, descent, and landing • Ensure system can attach to research computer payload • Ensure combined system can attach to Borealis balloon Performance • Log radiation and altitude data each second • Provide 5 watts per hour over 4 hour flight • Provide sound and/or light to indicate power is on • Provide sound and/or light to indicate the system is operating properly • • Ensure water cannot leak into system and payload floats Enable system to shut down if internal temperature exceeds 100 C • Ensure system can withstand vertical force of 10Gs and horizontal force of 5Gs (according to HASP requirements) • Ensure payload temperature stays within and will operate between -60 and 60C (external) and between -20 and 40C (internal) • Ensure pressure sensor can withstand 0-90kPa Physical • Ensure system does not exceed maximum dimensions: 5.5” by 5.5” by 5.5” • Ensure system does not exceed maximum mass: 6 lbs Reliability • Ensure system can launch twice and withstand internal tests: • Drop test • Bench-top burn test • Cold room test • Water resistance test • Pressure test • Recover all components and ensure internal components are not damaged Design Alternatives Arduino Uno Raspberry Pi Freescale Data Logger 25 + 20 + 13 = $58 25 + 13 = $38 13 + 13 + 20 = $46 45 + 10 = $55 Cost System Shield SD Card Total Mass System Shield SD Card Total 30 + 22 + 2 = 54g System SD Card Total 31 + 2 = 33g System SD Card Total System SD Card Shield Total 15 + 2 + 22 = 39g System SD Card Shield Total System x2 Micro SD 13 + Total 1 = 14g System x2 Micro SD Total Power 1.15 Watt 1.50 Watts .25 Watts .05 Watts Dimensions 2.95” x 2.09” 3.37” x 2.20” 3.2” x 2.1” 0.6” x 0.75” and 0.90” x 0.70” Input Voltage 7 – 12V 5V 5V 3.3 – 12V Non-Volatile Storage Separate SD Shield Built-in SD Shield Separate SD Shield Built-in Micro SD Shield and Flash Storage Sensor Interface UART to Geiger Counter Analog to Pressure Sensor UART to Geiger Counter I2C to Pressure Sensor UART to Geiger Counter Analog to Pressure Sensor UART to Geiger Counter Analog to Pressure Sensor Design Comparison Final Decisions and Budget Raspberry Pi: + SD Card: $25 Total: $38 $13 Computer Subsystem Tests Test 1- Connect Geiger counter to development board - Read and interpret data Test 2- Connect pressure sensor to development board - Read and interpret data while in pressure chamber Test 3- Write to SD card Program Design Radiation Sensors Sparkfun Geiger Counter SEN11345 Mighty Ohm Geiger Counter Kit Price $149.95 $99.95 Voltage Supply 5V (USB) 3V (two AA batteries) Temp Range -40 – 75C -60 – 70C Current 30mA 10mA Size 4.15” x 1.75” x 1” 4.75” x 2.75” x 1” Weight ~117g ~200g Ratings Additional Acrylic conformal coating to protect both Geiger counter and the rest of the circuit MG Chemicals 419C-340G MG Chemicals 419C-55ML Price $17.96 $10.95 Type Aerosol Liquid Size 12oz 2oz Max Temp 40C 40C Pressure/Altitude Sensor LPS331AP Pressure/Altitude Sensor HSCDLNN400MGSA5 SSCMRNN100PG4A5 Price $11.59 $35.45 $32.54 Temp Range -45 – 80C -20 – 85C -40 – 85C V In 2.5V 5V 5V Pressure Range 26 – 126kPa 0 – 40kPa 0 – 689kPa Analog vs Digital Output Digital Digital Digital Ratings Load DC/DC Converter XP Power Recom Power Rohm Rohm Semiconductor Semiconductor w/Heat Sink Fairchild Semiconductor Price $10.50 $7.49 $6.25 $6.25 $0.67 V out 5V 5V 5V 5V 5V I out 1A 1A 500mA 800mA 1A V in 6.5 – 18V 6.5 – 18V 6 – 14V 6 – 14V 5 – 18V Power 5W 5W 2.5W 4W 5W Temperature Range -40 – 85C -40 – 85C -30 – 85C -30 – 85C -40 – 85C Linear vs Switching Switching Switching Switching Switching Linear Efficiency 88 – 93% 89 – 94% 88% Nominal 88% Nominal NA External Components Capacitor Optional Blocking Diode NA Heat Sink NA Ratings Power Source Energizer Advanced Lithium Energizer Rechargeable Energizer Industrial Duracell Ultra Lithium Price $1.75 $1.89 $0.70 $1.50 Temp Range -40 – 60C -18 – 55C -18 – 55C -20 – 60C V Out 1.5V 1.5V 1.5V 1.5V Weight 14.5g 23.0g 23.0g 16.2g Configuration 5 Batteries 6 Batteries 8 Batteries +7.5V +9V +12V V Out DC/DC 5V 5V 5V P Out 2.5W 2.5W 2.5W I Out 500mA 500mA 500mA Efficiency 90% 90% 90% P In 2.8W 2.8W 2.8W V In 7.5V 9V 12V I In 370mA 310mA 230mA Configuration Energizer Advanced Lithium Energizer Rechargeable Energizer Industrial Duracell Ultra Lithium Time Cost Mass Time Cost Mass Time Cost Mass Time Cost Mass +7.5V 8hrs $8.75 72.5g 4.3hrs $9.45 115g 4.3hrs $3.50 115g 7hrs $7.50 81g +9V 10hrs $10.50 87g 5.65hrs $11.34 138g 5.7hrs $4.20 138g 10hrs $9.90 97.2g +12V 15hrs $14.00 116g 8.7hrs $15.12 184g 8.7hrs $5.60 184g 15hrs $12.00 129.6g Ratings Electrical Subsystem Tests Burn in test • Breadboard the design and power the circuit, to see how long the batteries last DC/DC converter test • Test to make sure the DC/DC converter is outputting the right value Cold test • Place the fully manufactured circuit in the enclosure and test the enclosure in the cold lab Final Decisions and Budget Geiger Counter: + Pressure Sensor: + DC/DC Converter: + Batteries: + Battery Boxes: + PC Boards: + Misc: $150 Total: $307 $33 $7 $80 $5 $12 $20 Structural Alternatives -Hard Foam -Gorilla Tape 1. -Packing Tape -Hard Foam -Gorilla Tape 2. -Packing Tape -Fiberglass -Thinsulate 3. -Fiberglass 4. -Vinyl Preliminary Testing- Prototype 1 Enclosure Specifications Pass? Attachment Impact Forces/Environmental Protection Specifications Pass? Specifications Pass? 5.5" cube yes Attach to Research computer payload* yes Meets HASP requirements for Gforces* yes Fits Electronics yes Attach to BOREALIS yes Buoyant &Water Resistant yes 0.1394 kg yes Electronics are secure yes Materials resist fire* yes Meets Internal Temperature Range* yes *Preliminary testing results to follow -Hard Foam -Gorilla Tape -Packing Tape -Fiberglass Attachment Method- Prototype 1 •Bottom of our payload will be bolted to top of research computer payload •Research computer payload will attach to BOREALIS Balloon -Prototype Lid -4 Screws -Prototype Box -Existing Research Payload Drop Test- Prototype 1 HASP Requirements Avg. Descent Rate BOREALIS Drop Test Results Impact Velocity (m/s) 3.13 7.62 14.9 Height (m) 0.546 3.43 11.3 Deceleration at Impact (m/s^2) 98.01 2,903 4,040 G-Force (G’s) 10 296 411.94 Internal Testing- Prototype 1 Burn test- tested material resistance to fire •Shredded Polyurethane Foam Burns only when flame is held on foam •Thinsulate Melts when flame is held on it but does not catch fire •Packing tape Melts when flame is held on it but does not catch fire •Polystyrene Foam Board Melts when flame is held on it but does not catch fire •Fiberglass Melts when flame is held on it but does not catch on fire Cold Test- Prototype 1 Test 1: No Thinsulate Bag, Shredded Packing Foam Test 2: Thinsulate Bag, Shredded Packing Foam Thermocouple on circuit board Test 3: Control Box: No Thinsulate Bag, No Shredded Packing Foam Thermocouple on battery pack Cold Room Test- Prototype 1 50 40 30 Temperature (⁰C) 20 Environmental Temperature 10 Test 1 Battery Thermocouple Test 2 Battery Thermocouple 0 Test 3 Battery Thermocouple Test 1 Thermocouple on Circuit Board -10 Test 2 Thermocouple on Circuit Board Test 3 Thermocouple on Circuit Board -20 -30 -40 -50 0 10 20 30 Time (minutes) 40 50 60 Budget Building Materials: $40 packing tape, fiberglass kit, gorilla tape, gorilla glue, etc. + Shredded Foam: + Polystyrene ½” Board: + Thinsulate: + TI Sensor Tag: Total: $2 $2 $15 $25 $84 Overall Budget CS Materials + EE Materials + ME Materials $38 Total: $429 $307 $84 $171 under budget!!! Computer Subsystem Anticipated Schedule Week 1: June 17 = Event = Milestone M T W R Week 2: June 24 F M T W R Week 3: July 1 F M T W R Week 4: July 8 F M T W R Week 5: July 15 F M T W R Week 6: July 22 F M T W R Preliminary Design Review Order Components Program Geiger Counter Interface Program Pressure Sensor Interface Program SD Card Interface Critical Design Review Full Program Design Test Support Software Full System Test Launch #1 Launch #2 (if necessary) Documentation Window Window F Electrical Subsystem Anticipated Schedule Week 1: June 17 = Event = Milestone M T W R Week 2: June 24 F M T W R Week 3: July 1 F M T W R Week 4: July 8 F M T W R Week 5: July 15 F M T W R Week 6: July 22 F M T W R Preliminary Design Review Order Components Circuit Design Bread Board Circuit Testing Critical Design Review Manufacturing Perform Additional Testing Full System Test Launch #1 Launch #2 (if necessary) Documentation Window Window F Mechanical Subsystem Anticipated Schedule Week 1: June 17 = Event = Milestone M T W R Week 2: June 24 F M T W R Week 3: July 1 F M T W R Week 4: July 8 F M T W R Week 5: July 15 F M T W R Week 6: July 22 F M T W R Preliminary Design Review Test All Prototypes Choose Optimal Prototype Simulation Testing Critical Design Review Manufacturing Perform Additional Testing Full System Test Launch #1 Launch #2 (if necessary) Documentation Window Window F Thank you!