BUZZSAT

CONTROL SYSTEM

Control System Electronics(CSE)

Digital Inputfrom ReceiverTransmitter

Power Microcontroller

Transmitter

ReceiverPower

ControlSystemPower

Attitude Control System(ACS)ACS

Power

ElectromagneticTorque System

4

Control System ArchitectureControl System Architecture

Microcontroller OptionsMicrocontroller Options

-UT80CRH196KDS Rad-HardUT80CRH196KDS Rad-Hard

-Microchip 18F452Microchip 18F452

UT80CRH196KDSUT80CRH196KDSAdvantages:Advantages: Radiation Hardened.Radiation Hardened.

Disadvantages:Disadvantages: No internal PROMNo internal PROM Fewer built in features than the MicrochipFewer built in features than the Microchip No previous Instruction Set ExperienceNo previous Instruction Set Experience Would have to find a hardware programmerWould have to find a hardware programmer The devices are still on backorderThe devices are still on backorder

Advantages:Advantages: Many built-in features like IMany built-in features like I22CC Simple to program using Prof. Peatman’s “QuikBug”Simple to program using Prof. Peatman’s “QuikBug” Instruction Set Experience (ECE 4175)Instruction Set Experience (ECE 4175)

DisadvantagesDisadvantages Not radiation hardened.Not radiation hardened.

Microchip 18F452Microchip 18F452

Which one?Which one?

Simple wiring interface, so why not just Simple wiring interface, so why not just make either one work. Work on the PIC make either one work. Work on the PIC with experience we already have and with experience we already have and simple programming, and get rad-hard simple programming, and get rad-hard processor to work when we actually get a processor to work when we actually get a flight slot.flight slot.

IR SensorsIR Sensors

IntroductionIntroduction General informationGeneral information ApproachApproach

Proposed functionality and designProposed functionality and design Challenges and constraintsChallenges and constraints Concluding remarkConcluding remark

Decision on this planDecision on this plan Other optionOther option

IR Sensors--IntroductionIR Sensors--Introduction

Taking into account the Inverse Square Law, at 400km from Taking into account the Inverse Square Law, at 400km from earth, IR sensors will distinguish the sun from the earth using earth, IR sensors will distinguish the sun from the earth using their different wavelength region of maximum intensity. their different wavelength region of maximum intensity.

Spectrum of the earth. The earth emits most of its radiation in a wavelength band between 0.5 and 30.0 micrometers (µm).

Spectrum of the sun. The sun emits most of its radiation in a wavelength band between 0.1 and 4.0 micrometers (µm).

IR Sensors--Functionality & IR Sensors--Functionality & DesignDesign

Using IR sensors that will check Using IR sensors that will check for radiation at ~10 micron, the for radiation at ~10 micron, the electromagnetic torque device will electromagnetic torque device will rotate the satellite so that the rotate the satellite so that the transmission link will be pointed transmission link will be pointed towards earth. towards earth.

IR

IR

IR

IR

IR

IRIR

IR (6371+400) km

6371 km

6371 km

43.3°

WavelengthWavelength IR detectors that detect at 10 microns are IR detectors that detect at 10 microns are

extremely rare.extremely rare.

MgCdTe (Mercury CadiumTelluride)MgCdTe (Mercury CadiumTelluride) A very fragile and difficult to process material, yet A very fragile and difficult to process material, yet

the only one to meet the wavelength requirement.the only one to meet the wavelength requirement.

RAD hardRAD hard Usually used in military applications.Usually used in military applications.

PricePrice Ranging in the thousandsRanging in the thousands

IR Sensors--Challenges & IR Sensors--Challenges & ComplicationsComplications

IR Sensors--Concluding RemarksIR Sensors--Concluding Remarks

ContactsContacts GTRI for regular IR sensors.GTRI for regular IR sensors. Judson Technologies for “special” IR sensors.Judson Technologies for “special” IR sensors.

DecisionDecision The cost of IR sensors is beyond the current budget.The cost of IR sensors is beyond the current budget.

Other optionOther option Permanent magnetic coils provided that satellite travels in Permanent magnetic coils provided that satellite travels in

inclined orbit, and not a polar orbit.inclined orbit, and not a polar orbit.

Direction Control by Direction Control by Electromagnets Electromagnets

Deviations from rotational orientation:Deviations from rotational orientation: Atmospheric drag (dominant for LEO)Atmospheric drag (dominant for LEO) Solar pressure on antennasSolar pressure on antennas Spacecraft bodySpacecraft body

Reason for direction control:Reason for direction control: Antennas need to point correctly at earthAntennas need to point correctly at earth

Direction Control by Direction Control by ElectromagnetsElectromagnets

Magnetic moment = NiAMagnetic moment = NiA N=# of turnsN=# of turns i = currenti = current A=cross-sectional areaA=cross-sectional area

Torque = (mag. moment) X (external field)Torque = (mag. moment) X (external field)

Direction Control by Direction Control by ElectromagnetsElectromagnets

Things to consider:Things to consider: Material for coilMaterial for coil Variation of earth’s mag. field vs position Variation of earth’s mag. field vs position MagnetometerMagnetometer

Shielding OptionsShielding OptionsRadiation-Radiation- Radiation is a real concern for Buzzsat Radiation is a real concern for Buzzsat electronics in space.electronics in space.

It can cause irreversible damage to the spacecraft electronics It can cause irreversible damage to the spacecraft electronics without shielding.without shielding.

It can cause sudden latch up in digital circuits, that can cause It can cause sudden latch up in digital circuits, that can cause improper logical operation.improper logical operation.

Shielding MaterialsShielding Materials Using a “sandwiching” technique where the circuits are covered on Using a “sandwiching” technique where the circuits are covered on

both sides with a shielding material.both sides with a shielding material. Lead is a possibility, and was proven to work with PCSAT.Lead is a possibility, and was proven to work with PCSAT. With a little bit of an investment, Rich Katz at NASA Goddard With a little bit of an investment, Rich Katz at NASA Goddard

recommends that we use a Tungsten/Copper alloy. recommends that we use a Tungsten/Copper alloy. This shield is highly effective. This shield is highly effective.

Shielding OptionsShielding Options

http://www.klabs.org/richcontent/General_Application_Notes/pshield_sanitized.pdfhttp://www.klabs.org/richcontent/General_Application_Notes/pshield_sanitized.pdf

ScheduleSchedule

ID Task Name Start End DurationJan 2003 Feb 2003 Mar 2003

1/5 1/12 1/19 1/26 2/2 2/9 2/16 2/23 3/2 3/9 3/16

1 26d2/10/20031/6/2003Project Design Phase

4 26d3/11/20032/4/2003Circuit Board

5 19d2/28/20032/4/2003Initial Bread Board Layout

6 9d3/5/20032/21/2003Printed Circuit Board(PCB) design

7 5d3/11/20033/5/2003PCB fabrication and shipping delay

8 33d3/14/20031/29/2003Attitude Control System (ACS)

9 13d2/14/20031/29/2003Electromagnetics Research

10 21d3/14/20032/14/2003Electromagnetic Integration

11 48d4/10/20032/4/2003System Integration & Test (I&T)

Apr 2003

3/23 3/30 4/6 4/13

17

14 35d4/10/20032/21/2003Testing and Integration

31d4/10/20032/27/2003Testing and Integration

3

2 22d3/5/20032/4/2003Microcontroller

22d3/5/20032/4/2003Programming

12 48d4/10/20032/4/2003Reciever

15 38d3/27/20032/4/2003Transmitter

13 14d2/21/20032/4/2003Command System Definitions

16 18d2/27/20032/4/2003Telemetry Technique Design

Material/Facility NeedsMaterial/Facility Needs

Circuit ComponentsCircuit Components These should be readily available from the Van Leer supply These should be readily available from the Van Leer supply

room.room.

Clean RoomClean Room While not necessarily needed right now, some of our more While not necessarily needed right now, some of our more

specialized components require a Class 10,000 to 100,000 specialized components require a Class 10,000 to 100,000 humidity controlled clean room.humidity controlled clean room.

PCB fabricationPCB fabrication Although there are facilities at the ECE building, it may be better Although there are facilities at the ECE building, it may be better

to use a commercial option, being that the turnaround time is to use a commercial option, being that the turnaround time is just a couple days. just a couple days.

Budgetary BreakdownBudgetary BreakdownMicrocontroller-Microcontroller- We have samples of both the PIC and We have samples of both the PIC and the UTMC microcontroller.the UTMC microcontroller.

Printed Circuit Board-Printed Circuit Board- this is from $50 to $100.this is from $50 to $100.

ACS-ACS- If we are not using $2000 IR detectors, then the most If we are not using $2000 IR detectors, then the most of the materials should be free. of the materials should be free.

Transmitter-Transmitter- The power switching device should be free The power switching device should be free radiation hardened or not.radiation hardened or not.

Receiver-Receiver- Most of these devices can be sampled for free.Most of these devices can be sampled for free.

System Integration and Test-System Integration and Test- There is really no cost here There is really no cost here other then time.other then time.

Shielding-Shielding- Rich Katz at NASA Goddard recommends Rich Katz at NASA Goddard recommends using a Tungsten/Copper Alloyusing a Tungsten/Copper Alloy. . This may cost around $100 This may cost around $100 dollars as well.dollars as well.

ReferencesReferences

www.boselec.com/products/www.boselec.com/products/

http://www.microchip.com/1010/index.htm http://www.microchip.com/1010/index.htm

www.utmc.comwww.utmc.com

www.expresspcb.com/www.expresspcb.com/

http://klabs.org/http://klabs.org/