Drexel RockSAT Critical Design Review

Kelly Collett • Christopher Elko • Danielle JacobsonDecember 8, 2011

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PDR Presentation Contents

• Section 1: Mission Overview• Mission Statement• Mission Requirements• Mission Overview• Concept of Operations• Expected Results

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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

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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

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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

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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.

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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

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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

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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

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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

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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

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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

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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.

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Physical Model

Microcontroller

Power Supply

Accelerometer Array

Piezo Arrays

Camera

Verification LED

Bridge RectifiersFlight

Decks

Standoff Supports

G-Switch

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Canister Fitment

4.313”

10.0”

Canister Partner’sSpace Allowance

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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.

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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

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PEA Design continued

Mounted to Lower Deck Use 4-40 x 3/8” Screws

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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

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Electrical Design continued

Piezoelectric Wire Output

LED

EPS Power Supply

Camera

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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

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Electrical Elements continued

Low-G Accelerometer

High-G Accelerometer

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Electrical Elements continued

Bridge Rectifier #1

Bridge Rectifier #2

Piezo Array

1

Piezo Array

2

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• Breadboard used for SD card and Arduino microcontroller integration

Electrical Elements continued

http://www.electronics-lab.com/blog/?m=200806

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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

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Software Elements

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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

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*/// 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

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#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

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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.

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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

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Prototyping continued

Preliminary piezo strip actuator voltage testing

for PEA design

Preliminary piezo strip actuator LED testing for

PEA-VVS interaction

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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

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Analysis FEA

PEAStress Analysis

• Point loadto simulate mass at end

• Uniform load to simulateG-loading

• Maximum stress doesnot exceed 2000 psi

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Analysis FEA

PEADeformation

Analysis

• Point loadto simulate mass at end

• Uniform load to simulateG-loading

• Maximum deformation:0.3 inches

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Analysis FEA

STRStress Analysis

• Point loadat electronic elements

• Uniform load to simulateG-loading

• Maximum stress doesnot exceed 649.6 psi

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Analysis FEA

STRDeformation

Analysis

• Point loadat electronic elements

• Uniform load to simulateG-loading

• Maximum deformation:0.92 inches

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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

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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

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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

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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.

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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

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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

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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

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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

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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

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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.

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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

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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.

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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

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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

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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

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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

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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

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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

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Organizational Chart

Danielle JacobsonElectrical Systems LeadMachining

Christopher ElkoStructural LeadCAD Designer

Kelly CollettTesting LeadPrimary POC

Drexel Space

Systems LabProject Support

Dr. Jin KangFaculty Advisor

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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

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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

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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

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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!

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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

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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

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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?

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Next Steps

• 3 days’ worth of sleep for each member of the team

• Prototype assembly• Testing testing testing!

Thank you!Questions?