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Drexel RockSAT Critical Design Review
Kelly Collett • Christopher Elko • Danielle JacobsonDecember 8, 2011
2
PDR Presentation Contents
• Section 1: Mission Overview• Mission Statement• Mission Requirements• Mission Overview• Concept of Operations• Expected Results
3
PDR Presentation Contents
• Section 2: Design Description• Off-ramps• Physical Model• Mechanical Design• Electrical and Software Design
• Section 3: Prototyping and Analysis• Mechanical Subsystems• Electrical Subsystems• Mass Budget• Power Budget
4
PDR Presentation Contents
• Section 4: Manufacturing Plan• Mechanical Elements• Electrical and Software Elements
• Section 5: Testing Plan• PEA Subsystem• EPS Subsystem• VVS Subsystem• Total System Testing
5
PDR Presentation Contents
• Section 6: Prototype Risk Assessment• PDR Risk Walk-down• Top CDR Risks
• Section 7: User’s Guide Compliance
• Section 8: Project Management• Organizational Chart• Schedule• Budget• Sharing Logistics
Mission OverviewDrexel RockSat Team 2011-2012
7
Mission Statement
Develop and test a system that will use piezoelectric materials to convert
mechanical vibrational energy into electrical energy to trickle charge on-board power
systems.
8
Mission Requirements
Number Requirement
MIS-REQ-1000 Must be able to convert vibrational energy to electrical energy
MIS-REQ-2000 Must be able to withstand launch environments
MIS-REQ-3000 Final design must meet RockSAT specifications
MIS-REQ-4000 Must be functional during flight
MIS-REQ-5000 Must not interfere with canister partner’s design
9
Mission Overview
• Demonstrate feasibility of power generation via piezoelectric effect under Terrier-Orion flight conditions
• Determine optimal piezoelectric material for energy conversion in this application
• Classify relationships between orientation of piezoelectric actuators and output voltage
• Data will benefit future RockSAT and CubeSAT missions as a potential source of power
• Data will be used for feasibility study
10
Concept of Operations
• G-switch will trip upon launch, activating all onboard power systems• Batteries power Arduino microprocessor and data
storage unit• Data collection begins
• Vibration and g-loads on piezo arrays create electric potential registered on voltmeter• Current conditioned to DC through full-bridge
rectifier and run to voltmeter• Voltmeter output recorded to internal memory• Data gathered throughout duration of flight
11
Concept of Operations
• Data acquisition and storage will enable researchers to monitor input from multiple sources• XY-plane vibrational energy• Z-axis vibrational energy
• Researchers will determine if amount of power generated is sufficient for the power demands of other satellites
• Include visual verification of functionality• Use energy from piezo arrays to power small LED• Onboard digital camera will verify LED illumination
12
Expected Results
• Piezoelectric beam array will harness enough vibrational energy to generate and store voltage sufficient to power satellite systems• Anticipate output of 130 mV per piezo
strip, based on preliminary testing.
• Success dependent on following factors:• Permittivity of piezoelectric material• Mechanical stress, which is related to the
amplitude of vibrations• Frequency of vibrations
Design DescriptionChristopher Elko
14
Subsystem Identification
EPS – Electrical Power Subsystem• Includes Arduino microprocessor, g-switch,
accelerometers, voltmeter, battery power supply, and all related wiring
STR – Structural Subsystem• Includes Rocksat-C decks and support columns
PEA – Piezoelectric Array Subsystem• Includes piezoelectric bimorph actuators,
cantilever strips, mounting system, rectifier, and related wiring
VVS – Visual Verification Subsystem• Includes digital camera, LED, and all related wiring
15
Off-Ramps VVS
• Main concern: Camera activation• Relaying the camera to the g-switch for
activation after launch will likely prove difficult.
• If this cannot be achieved on time, the VVS will be removed from the payload.• This will drop the mass of the payload
significantly, and will require additional ballast in its place.
16
Physical Model
Microcontroller
Power Supply
Accelerometer Array
Piezo Arrays
Camera
Verification LED
Bridge RectifiersFlight
Decks
Standoff Supports
G-Switch
17
Canister Fitment
4.313”
10.0”
Canister Partner’sSpace Allowance
18
Mechanical Design STR
Aluminum Standoffs
Stainless Fasteners
Clear Acrylic Flight Decks
¼” thick9.29” dia.QTY = 2
5/16” hexx 2 ¼” long
QTY = 5
8-32 thread
x 3/8” longQTY = 10
Fifth standoff column included to provide
support for EPS electronics mounted
to top deck.
19
Mechanical Design PEA
Aluminum Cantilever
FastenersPiezoelectric Strip
Support Block
Different orientations account for vibrations in
multiple planes.
PZT Ceramic40 mm x 10
mm5 mm thick
2 ¼” x ½”0.040” thick
20
PEA Design continued
Mounted to Lower Deck Use 4-40 x 3/8” Screws
21
Electrical Design
Piezoelectric Power OutputLED
Arduino Microcontroller
Camera
Power Supply
Rectifier
Piezoelectric Power Output LED
Rectifier
High-G Accelerometer
High-G Accelerometer
Low-G Accelerometer
Low-G Accelerometer
G-Switch
22
Electrical Design continued
Piezoelectric Wire Output
LED
EPS Power Supply
Camera
23
Electrical Elements
• Powered by 4 AA batteries• Connects directly to
microcontroller• Modified to incorporate G-
switch
To Bridge Rectifier
To Bridge Rectifier
LEDPiezo Arrays
(Battery)
G-Switch
BatteryPack Microcontroller
PEA-VVS Circuit Diagram G-switch interface with EPS
24
Electrical Elements continued
Low-G Accelerometer
High-G Accelerometer
25
Electrical Elements continued
Bridge Rectifier #1
Bridge Rectifier #2
Piezo Array
1
Piezo Array
2
26
• Breadboard used for SD card and Arduino microcontroller integration
Electrical Elements continued
http://www.electronics-lab.com/blog/?m=200806
27
Electrical Elements continued
• Two breadboards• LED circuit• SD card integration
• Allowance of 15-20 iterations to debug electronics• Limited previous exposure to programming
microcontrollers and EE in general• All electrical elements have been procured• Four dual-axis accelerometers have been
replaced with two three-axis accelerometers
28
Software Elements
29
Software Elements continued
Input Output Purpose
G-Switch T/F True/False Write to SD when T
Accelerometer 1 X
Voltage OutputsAll data output to SD card
via “write to file” command
Data Collection
Accelerometer 1 Y Data CollectionAccelerometer 1 Z Data CollectionAccelerometer 2 X Data Collection
Accelerometer 2 Y Data Collection
Accelerometer 2 Z Data Collection
Bridge Rectifier 1 Data Collection
Bridge Rectifier 2 Data Collection
Time (>1000s?) True/False End write command when T
Accelerometer Pseudo-Code
30
*/// these constants describe the pins. They won't change:const int groundpin = 18; // analog input pin 4 -- groundconst int powerpin = 19; // analog input pin 5 -- voltageconst int xpin = A3; // x-axis of the accelerometerconst int ypin = A2; // y-axisconst int zpin = A1; // z-axis (only on 3-axis models)
void setup(){ // initialize the serial communications: Serial.begin(9600);
// Provide ground and power by using the analog inputs as normal
// digital pins. This makes it possible to directly connect the // breakout board to the Arduino. If you use the normal 5V and // GND pins on the Arduino, you can remove these lines. pinMode(groundpin, OUTPUT); pinMode(powerpin, OUTPUT); digitalWrite(groundpin, LOW); digitalWrite(powerpin, HIGH);}
void loop(){ // print the sensor values: Serial.print(analogRead(xpin)); // print a tab between values: Serial.print("\t"); Serial.print(analogRead(ypin)); // print a tab between values: Serial.print("\t"); Serial.print(analogRead(zpin)); Serial.println(); // delay before next reading: delay(100);
SD Card Data Storage Code: Complete
31
#include <sd-reader_config.h>#include <sd_raw.h>#include <sd_raw_config.h>int print_disk_info();int sample();int readDisk();byte incomingByte;void printWelcome();long int address;byte tempBytes[2];void setup(){ Serial.begin(9600); delay(1000); printWelcome(); if(!sd_raw_init()) { Serial.println("MMC/SD initialization failed"); } print_disk_info();}void loop(){ int i; if(Serial.available()>0) {incomingByte=Serial.read();
switch(incomingByte) { case 114:
readDisk(); break; case 115: sample(); break; default: break;}}int sample(){ int i,j; int temp; byte low; byte high; byte inByte; Serial.println(); Serial.println(); Serial.println("Sampling..");
for(i=0;i<500;i=i+2) { if(Serial.available()>0)
{inByte=Serial.read();if(inByte==113) return 0;} temp=analogRead(0); Serial.print(temp,DEC); Serial.print(" "); //Convert int to 2 bytes low=temp&0xFF; high=temp>>8; // Serial.print(temp,DEC); //Serial.print(low,DEC); //Serial.print(high,DEC); tempBytes[0]=low; tempBytes[1]=high;
if(!sd_raw_write(i,tempBytes,2)) { Serial.print("Write error");
} //sd_raw_sync(); delay(5000);
Serial.println(); } return 1;}int readDisk(){ byte low; byte high; byte info[2]; int i; int result; Serial.println(); for(i=0;i<50;i=i+2) {sd_raw_read(i,info,2);
//Serial.print(info[0],DEC); //Serial.print(" "); //Serial.print(info[1],DEC); low=info[0]; high=info[1]; result=high<<8; //result<<8; Serial.print(" "); Serial.print(result+low,DEC); Serial.print(" ");}}
void printWelcome()
int print_disk_info(){ Serial.println("------------------------"); Serial.println("Data sampling system"); Serial.println("send r to read disk"); Serial.println("send s to start sampling"); Serial.println("send q to stop sampling"); Serial.println("Ready....."); Serial.println("-------------------------");}
{ struct sd_raw_info disk_info; if(!sd_raw_get_info(&disk_info)) { return 0; } Serial.println(); Serial.print("rev: "); Serial.print(disk_info.revision,HEX); Serial.println(); Serial.print("serial: 0x"); Serial.print(disk_info.serial,HEX); Serial.println(); Serial.print("date: "); Serial.print(disk_info.manufacturing_month,DEC); Serial.println(); Serial.print(disk_info.manufacturing_year,DEC); Serial.println(); Serial.print("size: "); Serial.print(disk_info.capacity,DEC);
{Serial.println(); Serial.print("copy: "); Serial.print(disk_info.flag_copy,DEC); Serial.println(); Serial.print("wr.pr.: "); Serial.print(disk_info.flag_write_protect_temp,DEC); Serial.print('/'); Serial.print(disk_info.flag_write_protect,DEC); Serial.println(); Serial.print("format: "); Serial.print(disk_info.format,DEC); Serial.println(); Serial.print("free: "); return 1;}
Prototyping and AnalysisChristopher Elko
33
PrototypingPEA
• Preliminary test setup measured voltage levels from a single strip actuator under deformation using a digital voltmeter.• Results suggest adequate voltage potential for
entire system, with an average of approximately 132 mVAC generated by a single actuator.
• Preliminary finite element analysis results in ABAQUS suggest aluminum is adequate for resistance to cyclic loading in this application.
• Mechanical analysis, in conjunction with destructive testing of piezo actuators, will optimize dimensions of support cantilever dimensions.
34
Prototyping continued
STR• Preliminary FEA results suggest a fifth aluminum
standoff is desirable for added support of electronic components on upper deck.
• Currently finalizing design and interactions with PEA mounting methods.
EPS• SD card adapter to be integrated• Accelerometers integrated into microcontroller
and tested for data output
VVS• Tested LED circuit for functional interaction with
PEA
35
Prototyping continued
Preliminary piezo strip actuator voltage testing
for PEA design
Preliminary piezo strip actuator LED testing for
PEA-VVS interaction
36
Analysis cantilever deflection
Point Load Distributed Load
• Maximum deformation at end of beam, where x = L• Combined loading
during flight due toG-loading and massat end of beam
37
Analysis FEA
PEAStress Analysis
• Point loadto simulate mass at end
• Uniform load to simulateG-loading
• Maximum stress doesnot exceed 2000 psi
38
Analysis FEA
PEADeformation
Analysis
• Point loadto simulate mass at end
• Uniform load to simulateG-loading
• Maximum deformation:0.3 inches
39
Analysis FEA
STRStress Analysis
• Point loadat electronic elements
• Uniform load to simulateG-loading
• Maximum stress doesnot exceed 649.6 psi
40
Analysis FEA
STRDeformation
Analysis
• Point loadat electronic elements
• Uniform load to simulateG-loading
• Maximum deformation:0.92 inches
41
Mass BudgetPart Mass (lbf) Qty Subtotal (lbf) Comment
STR
Flight Deck 0.84 2 1.68
Aluminum Standoff 0.02 5 0.1
PEA
Piezoelectric Arrays 0.01 4 0.04 Includes actuator, cantilever, mounting block, fastener, and deflection limiter
EPS
G-Swtich 0.014 1 0.014
Microprocessor 0.089 1 0.089
Bridge Rectifier 0.012 2 0.024
Accelerometers 0.002 2 0.004
AA Battery 0.0178 4 .0712 Includes battery holder
VVS
LED N/A 1 0 Negligible weight
Camera 0.0691 1 0.0691 Based on micro-camera, may change manufacturer
TOTAL 2.091
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Power BudgetPart Voltage (V) Current (A) Qty Time On (min) Amp-hours Comment
STR
Structure 0 0 0 10 0
PEA
PiezoElectric Actuators 0.13 V - 4 10 0 power generation part of project scope
EPS
G-Swtich 250VAC 5.00E+00 1 0.02 1.39E-03
Microprocessor 5V 4.00E-02 54 10 3.60E-01
Bridge Rectifier 20 1.00E+00 2 10 3.33E-01
Accelerometers 2.2-16 V 5.00E-04 2 10 1.67E-04
VVS
LED 0.055 V 5.00E-05 2 10 1.67E-05
Camera 10 Self-Contained
TOTAL 0.69
Manufacturing PlanChoose your weapon
44
Mechanical Elements
STR• Acrylic plate laser-cut to size/shape of flight decks• Flight decks among first components manufactured
to ensure proper interaction with other subsystems
PEA• Cantilevers cut to size from sheet aluminum upon
determining optimum • Piezo actuators to be bonded to cantilevers• Mounting blocks and deflection limiters must be
custom-milled from aluminum stock
45
Electrical Elements
EPS• Electronic interfaces will be table-tested with
breadboard and reconfigurable components• Testing will help to determine system capabilities
VVS• Testing will help to determine system capabilities
and effects on other subsystems
46
Code to be finalized• Accelerometers• Voltage output from bridge rectifiers• SD card data recording
Code to be developed• Power loop for camera• G-switch
Code block dependencies• SD card code integrates all subroutines• All code dependent on “true” output from G-switch
Software Elements
Testing PlanChoose wisely.
48
PEA Subsystem
Non-destructive Testing• Non-destructive testing
will determine voltage output from piezo actuators.
• Test Plan• Connect actuators to
voltmeter, LEDs; flex actuators to generate current
Destructive Testing• Will determine bending
deformation limits of piezo actuators.
• Test Plan• Use spindle micrometer to
bend piezos until fracture.
Piezo Actuator Tests
49
PEA Subsystem continued
Unrestricted Cantilever• Unrestricted cantilever testing will determine max
deformation limits of cantilevers and whether or not a block is needed to restrict deformation.
• Cantilevers will be designed so that they bend freely with only slight vibration.
• Test Plan• Set up cantilever assembly on vibe table• Measure deflection using high speed camera
Cantilever Tests
50
PEA Subsystem continued
Restricted Cantilever• Restricted cantilever testing will ensure that
designed block will restrict deformation as needed such that PEA won’t deform past piezo deformation limits.
• Block will be designed to restrict deformation in the + and – axis.
• Test Plan• Same as unrestricted tests except for use of block.
Cantilever Tests continued
51
PEA Subsystem continued
Thermal and Adhesive Tests• Thermal tests will be used to determine thermal
expansion of the piezos once adhered to the cantilever. This will ensure that the piezos don’t crack once adhered.
• Results will determine adhesive to be used.• Test Plan
• Adhere piezo actuator to cantilever material• Subject assembly to cyclic thermal environment• Bake in oven, then put in freezer
52
EPS Subsystem and Software
Arduino Sampling Rates• Tests will ensure Arduino board records at
highest sampling rate possible.• Test will be completed after all subsequent
electronics are tested.• Test Plan
• Connect all systems to Arduino board, click system on with G-switch
• Set resolution• Iteratively check data collection while increasing
sampling rates
53
EPS Subsystem and Software
Arduino Data Collection• Tests will ensure Arduino board records data as
required.• Test will be completed after all subsequent
electronics are tested.• Test Plan
• Connect all systems to Arduino board, click system on with g-switch.
• Check for data collection and storage.• Modify software as needed.
54
EPS Subsystem and Software
G-switch Program Test• Tests will ensure that G-switch activates system
with one click and does not deactivate the system on subsequent clicks.
• Test Plan• Program G-switch, connect to any system• Will test with dummy system and with full EPS system
once other tests are complete• Click system on, ensure function; click again, check
that system did not shut off
55
VVS Subsystem
Camera Activation• Tests will ensure camera relays function properly.
• Power down requirement includes camera. Camera will be relayed to g-switch to be activated upon launch.
• Test Plan• Connect camera to G-switch, click system on and
check that camera turns on and records.• Check that video saves at the end.
56
Full System Testing
Vibration Testing• Tests will ensure system is structurally sound
during vibration.• Test Plan
• Construct and connect full system• Use vibe table to simulate Terrier-Orion flight
vibration conditions• Monitor system connections and structural
integrity throughout test• Check for data collection on Arduino board and
camera at end of tests
57
Full System Testing
Spin Testing• Tests will ensure system is structurally sound
during spin.• Test Plan
• Construct and connect full system• Use spin table to simulate spin of Terrier-Orion
rocket• Monitor system connections and structural
integrity throughout test• Check for data collection on Arduino board and
camera at end of tests
Prototype Risk Assessment
Kelly Collett
59
Prototype Risk Assessment
EPSFunctionality of microcontroller must be verified
by CDR
Prototype controller on
bread board to verify function
PEABond between PE
actuators and aluminum must
not fail
Test various bonding materials
and application methods
STRConcerns exist
about clearance and
component mounting
Prototype all interfaces with STR to ensure
integrity
Risk/Concern ActionSubsystem
VVSLED must light,
camera must not fail to record
actions of LED
Test LED with PEA to
verify power draw;test camera to
ensure functionality
60
Risk Walk-Down risks at PDR
Consequence
EPS.RSK.2 EPS.RSK.1 PEA.RSK.2
STR.RSK.1
PEA.RSK.1
VVS.RSK.1 VVS.RSK.2
Possibility
• STR.RSK.1 – Clearance and component mounting
• PEA.RSK.1 – Bonds between PE actuators and cantilevers must not fail
• PEA.RSK.2 – PEA actuators cannot fracture
• EPS.RSK.1 – Functionality of Microcontroller
• EPS.RSK.2 – G-switch must not shut off system
• VVS. RSK.1 – LEDs must light
• VVS.RSK.2 – Camera must record LED light and cantilever deflection
Risk Matrix at PDR
61
Risk Walk-Down top 3 risks at CDR
Consequence
EPS.RSK.2 EPS.RSK.1 PEA.RSK.2
Possibility
• Top 3 Risks• PEA.RSK.2
PEA fracture• EPS.RSK.2
G-switch• EPS.RSK.1
Microcontroller
• Will be walked down with testing
Top 3 Risks Remaining
User’s Guide ComplianceKelly Collett
63
User’s Guide Compliance
Magnitude of Mass• Approximately 2.091 lbf (without ballast)
CG
• Lies within 1 in.3 volume at center
Power Requirements• Low voltage electrical components used• Batteries
• 4 x 1.5-V AA = 6 V
Project Management PlanKelly Collett
65
Organizational Chart
Danielle JacobsonElectrical Systems LeadMachining
Christopher ElkoStructural LeadCAD Designer
Kelly CollettTesting LeadPrimary POC
Drexel Space
Systems LabProject Support
Dr. Jin KangFaculty Advisor
66
Schedule December & January
Testing12/1 Prelim. cantilever FEM
12/12-22
G-Switch programming
Arduino software programming
Destructive piezo testing
Cantilever tests
1/9-24 Thermal / Adhesive Tests
Software Iterations
VVS Camera Tests
Preliminary EPS Integration
Redesigns, if necessary
Deliverables12/8 CDR Due
12/13
CDR Teleconference
Temple CDR Teleconference
1/9 Flights Awarded
1/30 Online Progress Report due
67
Schedule February & March
Testing DeliverablesFebruary
2/6 Midterm Draft Report Due
2/13
Subsystem Test Reports Due
2/27
Progress Presentation to Faculty Advisor
March
3/12
Online Progress Report due
3/19
Project Progress Report due
FebruaryVVS TestingRe-test of any redesignsFull system hook-up tests
68
Schedule May
Testing Deliverables5/7 Weekly Teleconference
5/14 Weekly Teleconference
Senior Design Project Report Due
5/21 Weekly Teleconference
5/21-5/22
Final Senior Design Presentations
5/28 LRR Presentation Due
5/29 LRR Teleconference
5/30 CoE Project Competition
Subsystem and system testing, troubleshooting, and modifications as needed
69
Budget
Spending to date: $238.48Estimated final total: $503.23
Budget: $1,000 Lookin’ Good!
Major Cost ContributorsDigital Camera: $140Piezoelectric Components: $100
Major Time ContributorsPiezoelectric Components: 7-10 DaysAccelerometers: 7-10 Days RECEIVED!
70
Budget Ordered Parts ($238.48)
Item Subsystem Supplier Cost/Set or Unit Sets Subtotal
Bridge Rectifier EPS DigiKey $0.62 2 $1.24
Piezo Actuator PEA STEMInc. $19.98 1 $19.98
Piezo Actuator PEA STEMInc. $19.98 2 $39.96
Piezo Actuator PEA STEMInc. $19.98 2 $39.96
12” x 12” Acrylic Sheet STR McMaster $7.23 2 $14.46
3-Axis Accelerometers EPS Pololu $14.95 2 $29.90
G-Switch EPS DigiKey $4.39 2 $8.78
Arduino MEGA Microprocessor EPS SparkFun $58.95 1 $58.95
Aluminum Standoffs STR McMaster $1.05 5 $5.25
Miscellaneous Fasteners STR McMaster $20.00 allowance N/A $20.00
71
Budget To Be Ordered ($290)
• Camera ($140)
• Circuitry Components ($100)• Parts for testing and installation• We have some spare parts, so orders will be
made on an as-needed basis
• Structural Materials ($50)• We have some spare materials, so orders will
be made on an as-needed basis
72
Sharing Logistics
Temple University• Plan for Collaboration
• Email, phone, campus visits• Full model designed in
SolidWorks for fit check• DropBox/Google Docs for
file sharing
• Structural interface• Consider clearance• Joining method
ConclusionsWhat’s Next?
74
Next Steps
• 3 days’ worth of sleep for each member of the team
• Prototype assembly• Testing testing testing!
Thank you!Questions?
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