sponsoring stevens institute of technology rocksat-c 2013 2013/2013cdr... · electrical design...

New Jersey Space Grant Consortium sponsoring

Stevens Institute of Technology

RockSat-C 2013 Critical Design Review

Mike Giglia

Ethan Hayon

Mark Siembab

~~~~~~~~~~~~~mentoring~~~~~~~~~~~~~~~~~~~~

Andrew Cupo Palash Mehta

Thomas De Girolamo Jason Robbins

Andrew Deutchman Jeremy Simoes

Anthony Di Girolamo

Stevens Institute of Technology with New Jersey Space Grant, November 2012

Presentation Contents

• Section 1 : Mission Overview o Mission Statement

o Organizational Chart

o Concept of Operations

o Project Objective

o Requirements and Expectations

• Section 2 : Design Description o Requirement/Design Changes Since PDR

o De-Scopes / Off-ramps

o Mechanical Design Elements

o Electrical Design Elements


• Section 2 (cont.) o Science Description

• Section 3 : Prototyping / Analysis o Analysis Results

o Prototyping Results

o Detailed Mass Budget

o Detailed Power Budget

o Detailed Interfacing to Wallops

• Section 4 : Manufacturing Plan o Mechanical Elements

o Electrical Elements

o Software Elements


• Section 5 : Testing Plan o System Level

o Mechanical

o Electrical

o Software

• Section 6 : Risks o Risk Matrix

o Critical Risks Remaining

• Section 7 : User Guide Compliance o Compliance Table

o Sharing Logistics


• Section 8 : Project Management Plan o Schedule

o Budget

Mass

Monetary

o Work Breakdown Structure

Section 1

Mission Overview

Mission Statement

• To design and create a cost effective fiber

optic gyroscope and gather accelerometer,

gyroscopic, temperature, pressure, and

temperature data for use in future space

flight.

Organizational Chart

Concept of Operations

Project Objective

• The purpose of the project is to design and

develop a cost effective space canister that

is able to gather data from various different

sensors, including a fiber optic gyroscope,

accelerometers, and temperature sensors.

Requirements and Expectations

• We are expecting to run several different experiments

in the conditions present on the rocket:

o Aerogel Insulation Study

o Thermoelectric Generator Temperature Sensing

o 3-axis Fiber Optic Gyroscope

o Accelerometer testing

• Requirements:

o Payload must be able to withstand the conditions

of flight

This includes the large stresses due to

acceleration, high heat, and limited space

Discoveries??

• With this project, we hope to discover...

o A low-cost Fiber Optic Gyroscope that has decent

tolerance to rocket flight conditions and can

accurately measure rocket angular velocity

o A correlation between different types of aerogel

and their insulating capabilities

o A method for in-flight thermoelectric energy

generation and storage

o A method for measuring the air pressure inside the

canister to analyze when and why malfunctions

such as leakage take place (if any)

Expected Results

• Thermoelectric generator power trends o Steady increase from launch to 0.6 minutes

0 to maximum velocity (end of Orion burn)

o Steady decrease from 0.6 minutes to apogee

No longer under acceleration

Lower density of air at higher altitudes = lower

skin friction = lower temperature

o Small increase from apogee to chute deploy

Caused by tumbling of rocket

o Slight increase from chute deploy to splashdown

Caused by solar heat

Expected Results Continued

• Optical Gyroscope (FOG) o Similar data to a MEMS gyroscope with the FOG

achieving much higher output resolution

o Expected measurable spin rate of the rocket

1.3Hz at Terrier burnout

5.6Hz at Orion burnout

o What don't we know?

How does the rocket tumble from apogee to

chute deploy?

Can we use our data to design a system to

prevent this tumbling?

Section 2

Design Descriptions

Requirements / Changes Since PDR

• Using a larger radius for the X and Y axis

FOG to increase sensitivity. o 1.5" radius instead of 0.75"

De-scopes and Off-ramps

• None yet; Elements of the TEG experiment

may need to be adjusted upon receiving a

response from Wallops o Possibilities include:

Reduction in size and/or number of modules

Total elimination (we hope not)

Mechanical Design Elements

• Utilization of three aluminum plates equally

spaced apart o During prototyping, plastic plates will be

implemented when fitting and outlining where the

components will be mounted

o Aluminum plates will be used in the final design

due to its higher strength and the possibility of the

plastic plates cracking during space flight

• Central Plate o Fiber Optic Gyroscope

Z-axis wrapped around mounting brackets

within the circumference of the aluminum plate


X-axis and Y-axis will be mounted within

the middle of the central aluminum

plate • Cut-outs will be made in order to allow the fiber optic to be wrapped cylindrically

and secured to the fabricated mounting brackets

• The X-axis and Y-axis will meet at a corner where it will be secured to a one-

piece bracket

• Top Plate

o Data Logging

Beaglebone ARM System on chip (microcomputer)

Base sensor suite • Accelerometer, MEMS Gyroscope, Barometric Pressure Sensor, Ambient

Temperature Sensor


• Bottom Plate o Power Distribution

Input from battery • Split into different voltages through voltage regulators

• Will have rows of different pins based on what is needed

Latch Circuit • Two wires provided by NASA to enable the canister

• Based on position in the canister, the components located

on the top and bottom plates may be switched

o Dependent upon where the center of mass is positioned

amongst the payload

It is imperative to have the center of mass properly

positioned at the center of the payload

Mechanical Design: 3D Models

Mechanical Design Elements:

Window

• Modular mounting plate located on surface

of rocket like a conventional window. o Milled from aluminum

o contains four recessed compartments for four types

of 40mm TEG modules and heat sink covers.

o Contains mounting areas for thermocouple

temperature sensors

o Designed to optimize heat transfer across TEG

modules for maximum power delivery

o Designed to minimize shear stresses associated

with acceleration in the z-direction

Electrical Design Elements: BBCape

• Shield for Beaglebone embedded linux

board (also known as a cape)

• Interface with all other electronic elements

• Base Experiments o Ambient Temperature

o MEMS Gyroscope

o Barometric Pressure

o Accelerometer

• Connections to: o FOG Interface board (x3: X,Y,Z) - Discussed later

Electrical Design Elements: BBCape

Electrical Design Elements: PDB

• Power Distribution Board (PDB)

• FET to switch payload on with command

line activation

• Once activated, little to no current will

flow across the activation lines

• Voltage regulators for use throughout the

payload o 1.25V, 3.3V, 5V

• Modular connectors - easy to add and

remove peripheral devices

Electrical Design Elements: PDB

Electrical Design Elements: FOG

Interface

• Fiber Optic Gyroscope Interface Board

• Interface with the laser and photodiode for

each axis

• Switch laser on and off

• Optional Amplifier and Jumper circuitry to

amplify the the photodiode output if necessary

• Send the data back to the Beaglebone for

processing

o JST connectors used everywhere for easy

connection and disconnection. Will be

fastened with silicone prior to launch.

Electrical Design Elements: FOG

Interface

Electrical Design Elements: TEG

• TEG Interface and Energy Harvesting Board

Electrical Design Elements: TEG

• Capacitor Bank Design o Using the equation Vc = V * (1- e^(-t / R*C)) with

highly conservative assumptions:

Unlimited current supplied by LTC3109

V = Peak supply voltage = 5.25V

t = Maximum generating time = 10 minutes

R = Typical supercapacitor ESR = 16 ohms

Vc = max allowable instantaneous capacitor

voltage = ~5.1V

=> A 10 Farad supercapacitor (C_store)

will be sufficient for each charging circuit

Section 3

Prototyping / Analysis

Optical Gyroscope Prototyping Plan

The Problem in a nutshell

• When the canister rotates in a certain axes, the light output

from the FOG will always be at a different place than where

it came in. This change in position is known as phase shift.

• Unfortunately, since the Interference Irradiance of light is

periodic, there will be certain points in the wave where the

irradiance will be the exact same. Hence this does will not

accurately represent how much the rocket actually rotated.

• To fix this problem, we must bound the periodic wave to

only half a wave and calculate the upper bound of the

number of loops of wire the FOG can have.


• The FOG will be prototyped using a laser,

photodiode and 2x2 coupler. We have

already received the laser and photodiode

and are waiting on the arrival of the 2x2

coupler to begin prototyping.

• We will also intend to calibrate the FOG

using a turntable, by having the payload

mounted to the spinning turntable and

adjusting the rotation speed.


2mW MQW-DFB

Optical Source

(1310nm)

1310nm PIN

photodiode

Layout of the FOG

• The FOG will be spread out over two of the

payload plates o X and Y axis will sit on the bottom plate

o Z axis will wrap around the center plate

o X and Y axis may protrude through plate above and

below depending on the height of the standoffs

FOG: Z Axis Mount Prototype

Prototype: Plates

• The base plates will be prototyped with

1/8" thick acrylic. o Can easily be cut on the laser cutter in the

Carnegie lab

o We can ensure that mounting locations are correct

before getting the final plates manufactured.

• Final plates will be cut out of 1/8" thick

6061 Aluminum. o Due to large cut outs on plate, we will use

aluminum. We understand the potential problems

this creates: short circuits, etc...

Prototype: FOG Mounting Brackets

• Mounting brackets for fiber optic cable o Prototyped in ABS Plastic printed on 3D printer

o Helps us figure out how to route the fiber optic

cables on the payload plate.

• Final mounting brackets o Milled out of a block of 6061 Aluminum.

o If weight is an issue, we may end up using the 3D

printed parts on the flight payload.

Prototype: Custom Window

• If possible, we plan to print a full scale

custom window on the 3D printer.

• Make sure that the geometry is correct

• Fit-checks with the thermoelectric

generator modules and aerogel to ensure

they fit.

Detailed Mass Budget

• Mass Budget

o Assuming Aluminum plates

Detailed Power Budget

-All sensors are based on highest possible power

consumption

-Total budget as of now comes out to 2523 Joules, or

.000701 kWh

-Temp Sensors not chosen, power consumption should not

be noticeable

Detailed Interfacing to Wallops

• Custom Window for Thermoelectric Power

Generation experiment

• T-5 minutes command line activation o Circuit designed using MOSFET with pull-down

resistor to ensure that once activated, large

current will not flow across the activation lines

Section 4

Manufacturing Plan

Carnegie Laboratory

• The NJ Rock-SAT group teamed up with the

Design and Manufacturing Institute within

Stevens Institute of Technology o Parts will be prototyped and manufactured in our

"Carnegie Laboratory"

o Machines include:

FDM 3D Printers

5-Axis CNC Mill

Laser Cutters (for Acrylic)

• Carnegie machine shop will use a laser

cutter to cut acrylic plates for fit checks.

• Once the mounting locations have been

finalized, they will machine the finished

design out of 1/8" thick aluminum.

Mechanical: Plates

Mechanical: Fiber Optic Gyroscope

• The X, Y, and Z axis mounting system for

the FOG will be built on a 3D printer.

• We have tested the parts printed and they

are stronger than we expected. o No concerns with using them on the flight payload.

Z-Axis Mount X/Y Axis Mount

Electrical Elements

• Electrical components purchased from

multiple suppliers o FOG : www.lightwavestore.com,

www.fiberstore.com

o General Electronics: www.digikey.com,

www.sparkfun.com

• Printed circuit boards manufactured by

Advanced Circuits o www.4pcb.com

Electrical Elements

• First revision of printed circuit boards has

been ordered.

• We will test the boards and make necessary

adjustments.

Software

• Software is being developed to read in data

from each sensor individually.

• Will be combined into multiple "threads"

which will be executed at T-5 minutes of

launch.

• Successfully reading from TMP102 ambient

temperature sensor and LIS331 3-axis

accelerometer

Software: LIS331 and TMP102

Sample Data:

LIS331 Accelerometer TMP102 Temperature Sensor (C)

Section 5

Testing Plan

System Level Testing

Several tests will be conducted in order to be

sure no failures occur during flight:

• Vibration test of assembled payload

• Controlled temperature differential test for

TEG experiment

• Calibration and spin tests of FOG

• Evaluation of PDB and activation circuitry

to ensure conformity with Wallops'

requirements

Electrical Testing

• Ensure that there are no short circuits

• Continuity checks between ground and

plates (infinite resistance expected)

• Voltage: V_RBF to be zero

• Current: I_RBF < 750mA

Mechanical Testing

• The payload will undergo shake and

vibration tests o Paint shaker test similar to the one performed last

year

o Ensures that all mechanical connections are solid

o Will show us where we have loose hardware /

fasteners

o Should give us some useful accelerometer

measurements.

Gyroscopic Calibration

• Once the gyroscope is created on the plate we

can create our voltage to angular velocity

function o To do this we will test the gyroscope at ten different

known angular velocities and measure the voltage

Given this data we can create a general function

for all angular velocities to plot once voltage data

is saved during flight.

• A turntable is being designed to aid in the

calibration process. Payload will be calibrated

before launch at Wallops.

TEG Testing

• Performance of two TEG modules has been

tested at excessive temperature

differentials (~750 F)

• Waiting for delivery of LTC3109 ICs and

breakout boards for bread board testing o All other charge circuit components have been

obtained

• Adjustments will be made to Eagle files

prior to ordering complete PCBs.

Software Testing

• We will fully simulate flight.

• We will manually activate the payload and

let it record data for at least 2 hours.

• Throughout the test the payload will be

moved in various directions to ensure the

FOG and MEMS gyroscope are gathering

proper readings.

• Bring the payload outside to check

temperature readings.

Miscellaneous Testing

• Vibration Testing o Use of a high rotating paint shaker to test the

durability of the standoffs, plates, and all other

attached components.

Section 6

Risks

Risk Matrix

1) Aluminum Plates create

a short circuit

2) TEG modules crack due

to vibrational stresses

(brittle ceramic)

3) Heat difference on outer

circumference of FOG

distorts phase shift

1

2

3

Risk Matrix

• Risk 1 can be avoided by taking care to insulate all

bare connections and assembling circuit boards so that

mounting screws do not contact traces.

• Risk 2 must be accepted; there is not adequate room

to provide an ideal dampening system to the modules

• Risk 3 can be mitigated by wrapping the outer

circumference of the FOG with insulating material

such as adhesive foam weather stripping. o UPDATE (12/1): Instead, we will take temperature readings throughout

the payload and create a mathematical function to fix our data.

Refractive index is a function of wavelength and temperature.

Critical Risks Remaining

• Aluminum plates create a short circuit. o Payload has not been constructed yet, so this is

still a critical risk!

Section 7

User Guide Compliance

Compliance Table

• Mass of payload = 6.5lbs

o Current model is 3.57 (missing the

battery and some of the heavier

components)

• Mass of canister = 7.0lbs

• Total mass of canister & payloads

= 20.0lbs

• Center of mass is within the

1"x1"x1" envelope required by

Wallops. (-0.05x, -0.07y, -0.16z)

• Rechargeable NiMH batteries will

be used.

• We will require T-5 minutes

command line activation

Sharing Logistics

• Working with Mitchell Community College

• NJSGC worked with Mitchell CC in 2012 o Plan to use similar communication

Dropbox for Solidworks models

Email/IM for any other communication

Possible teleconferences when necessary

Section 8

Project Management Plan

Schedule

Tentative schedule for prototyping / development phase

• 12/2 - Submit CDR

• 12/6 - Present the CDR

• 12/4 - Begin full prototype of FOG Z axis

• 12/22 - Receive manufactured plates from machine shop *

• 12/23 - Mock assembly of entire payload

• 12/26 - Submit designs for aluminum "flight" plates

• 1/3 - Receive final plates and begin assembly *

• 1/20 - Begin extensive component testing

• 1/27 - Begin system testing

• Finish system testing by the middle to end of February

* subject to change

Budget (Updated from PDR)

Work Breakdown Structure

Project Summary

• Remaining issues: at this time our primary

issue concerns the design and fabrication of

our custom window. We hope that Wallops

will be able to provide us with the

accommodations we require for this.

• Concerns: o We are working to make up the time we missed due

to the hurricane.

o We are hoping the machine shop at Stevens is still

willing to share their resources with us.

Conclusion

• We plan to finish prototyping all circuitry

and complete the Eagle CAD models of each

• Before winter break we hope to: o have the first revisions of all circuit boards ordered

o order all additional components

o assemble and calibrate the FOG

sponsoring stevens institute of technology rocksat-c 2013 2013/2013cdr... · electrical design...

Documents