P09141 Satellite Thermal Heater Controller Anthony Berwin Mechanical Engineer Scott Rioux Industrial Engineer Greg Pawlowski Electrical Engineer Sarmad Abedin Electrical Engineer John Scipione Electrical Engineer Sponsors: ITT Corporation & D3 Engineering 1Project Review RITKGCOE Multidisciplinary Senior Design

Project Overview  Description: Thermal Controller for Satellite Operations  Market: Space Systems Division of ITT  Key Deliverables: 1. Power Efficiency 2. Mass 3. Performance 4. Communications 5. Cost 2Project Review RITKGCOE Multidisciplinary Senior Design

Project Concept  Enclosure  Interface Board  Communications  Programming  Protocol  GUI 3Project Review RITKGCOE Multidisciplinary Senior Design

Project Architecture 4Project Review RITKGCOE Multidisciplinary Senior Design

Milestones  MSD 1  January 16, 2009 – System Level Design Review  February 13, 2009 – Detailed Design Review  February 20, 2009 – Project Presentation  MSD II  March 9, 2009 – Begin Programming DSP & GUI  March 13, 2009 – Materials Ordered  April 3, 2009 – Testable Prototype  May 1, 2009 – Testing & Debugging Completed  May 20, 2009 – Final Review Project Review RITKGCOE Multidisciplinary Senior Design 5

Budget/BOM  Original Budget: $1740 – $2070  Current Estimated Budget: $  All components available  Shipping time 1-2 weeks  Waiting on DSP’s  Machine time for Enclosure 2 weeks, could outsource for faster turn around time Project Review RITKGCOE Multidisciplinary Senior Design 6

Enclosure Needs & Specifications  Size (Minimize)  Mass (<0.3 lb)  Mounting (Enclosure, PCB, Connectors*)  Vibrations (23.1 G’s Random Vibration)  Thermal (-40°C to +55°C)  Vacuum Environment  Ventilation* (<1 psi/s)  Outgassing  Torque on Screws*  EMI Leakage* (<100 kHz) 7Project Review RITKGCOE Multidisciplinary Senior Design

Enclosure Assembly Model 8Project Review RITKGCOE Multidisciplinary Senior Design

Enclosure Assembly Model: Exploded View 9Project Review RITKGCOE Multidisciplinary Senior Design Top Side B Side A PCB Base

Enclosure Specifications Met  Total Size: 2.875” x 2.875” x ”  Size of the PCB with the Connectors: 2.61” x 2.25” x ”  Total Mass: lb  18% below the 0.3 lb limit  Enclosure Mounting:  Flat Plate & Cylinder (R>18”)  PCB Mounting:  Four (4) Screws & Aluminum Heat Sink Contacts 10Project Review RITKGCOE Multidisciplinary Senior Design

Enclosure Specifications Not Met  Partially Met  Connector Mounting  Vacuum Environment  Ventilation  Outgassing  Not Met  Torque on Screws  EMI Leakage 11Project Review RITKGCOE Multidisciplinary Senior Design

Enclosure Risk Assessment: Risks  Acquiring PCB Specifications  Acquiring Connector Specifications  Acquiring Equipment (PCB & Connectors)  Stress on the Screws  Enclosure Strength 12Project Review RITKGCOE Multidisciplinary Senior Design

Enclosure Risk Assessment: Actions  Acquiring PCB Specifications  Delay in the redesign of the enclosure or causing a redesign much later in MSD II  Acquiring Connector Specifications  Delay in the redesign of the enclosure or causing a redesign much later in MSD II  Acquiring Equipment (PCB & Connectors)  Delay in the assembly of the enclosure  Stress on the Screws  Failure during vibrations testing  Enclosure Strength  Failure during vibrations testing 13Project Review RITKGCOE Multidisciplinary Senior Design

Enclosure Risk Assessment: Mitigation  Acquiring PCB Specifications  Work with the customer to clarify specifications  Acquiring Connector Specifications  Work with the customer to clarify specifications  Acquiring Equipment (PCB & Connectors)  Work with the customer to receive the equipment  Stress on the Screws  Increase screw size  Use temporary thread-locking adhesive  Enclosure Strength  Change material to aircraft aluminum 14Project Review RITKGCOE Multidisciplinary Senior Design

Enclosure Action Items  Redesign of the enclosure  Increase screw size  Change material to aircraft aluminum  Final PCB Specifications  Complete  Part Models  Assembly Model  Part Drawings  Parts List  BOM  Enclosure Specifications  Thermal and Vibrations Simulations 15Project Review RITKGCOE Multidisciplinary Senior Design

Interface Board Overview  Purpose  Master and slave communications over a power bus  Isolation from 28VDC Power Bus  Transmit/Receive Switching  Transmit/Receive Signal Conditioning  Voltage conversion 16Project Review RITKGCOE Multidisciplinary Senior Design

Interface Board Block Diagram 17Project Review RITKGCOE Multidisciplinary Senior Design

Interface Board DC Isolation 18Project Review RITKGCOE Multidisciplinary Senior Design  Need  There are no dedicated communication lines  RF signals will interfere with other satellite operations  Power bus already available  Isolation of communications signal from DC power bus to protect electronics

Interface Board Switching 19Project Review RITKGCOE Multidisciplinary Senior Design  Need  Transmitting the communications signal  Receiving the communications signal  It is necessary to switch between the two modes of operation

Interface Board Voltage Converter 20Project Review RITKGCOE Multidisciplinary Senior Design  Need  Negative supply voltage to operate electronics on interface board  Will take a input voltage and output the same negative voltage

Interface Board Receive Signal Conditioning 21Project Review RITKGCOE Multidisciplinary Senior Design  Need  Filter out noise from communications signal  Amplify communications signal for ADC  Offset communications signal to positive voltage for ADC

Interface Board Transmit Signal Conditioning 22Project Review RITKGCOE Multidisciplinary Senior Design  Need  Filter out high frequency harmonics from communications signal  Generate the communications signal from pulse width modulator

Interface Board Risk Assessment: Risks 23Project Review RITKGCOE Multidisciplinary Senior Design  Low frequency noise not filtered out  Transient noise not accounted for  Power consumption of IC’s  Design of filters

Interface Board Risk Assessment: Actions 24Project Review RITKGCOE Multidisciplinary Senior Design  Low frequency noise not filtered out  Communication errors, or signal not received  Transient noise not accounted for  Communication errors, or signal not received  Power consumption of IC’s  Use to much power, other systems will not work  Design of filters  Filters do not function properly

Interface Board Risk Assessment: Mitigation 25Project Review RITKGCOE Multidisciplinary Senior Design  Low frequency noise not filtered out  Transient noise not accounted for  Write better demodulation algorithm, use more hardware demodulation techniques  Power consumption of IC’s  Switch to low power modes when not in use  Design of filters  Do more research on filter design, or seek help in filter design from experienced engineers

Interface Board Action Items 26Project Review RITKGCOE Multidisciplinary Senior Design  Finalize parts for interface board  Build prototype and test

Programming Architecture 27Project Review RITKGCOE Multidisciplinary Senior Design

Programming Needs  PC communicate with Master DSP over serial line.  Master DSP communicate with each slave over 28V heater power bus. No dedicated lines are available.  Modulation and demodulation is needed. 28Project Review RITKGCOE Multidisciplinary Senior Design

Programming DSP  The bits of the protocol must be generated, stored, and interpreted.  A sine wave must be generated from binary using PWM/ DAC.  Signal demodulated back into binary using ADC.  Communication with the PC GUI over SCI. 29Project Review RITKGCOE Multidisciplinary Senior Design

Programming How are we going to do it? 30Project Review RITKGCOE Multidisciplinary Senior Design  Code Composer will be used to Program the DSP in the C programming language.  The ADC, PWM, UART, and SCI modules are all utilized. The program is stored in flash memory. The protocol bits are stored in RAM memory.

Programming Risks  Acquiring the DSP. Programming will be difficult to begin without the DSP.  Learning the Code Composer Environment. Code Composer comes with the DSP.  Programming each of the DSP elements that need to be programmed including PWM, ADC, the protocol, serial communication.  Finding code examples.  Writing and testing the code. 31Project Review RITKGCOE Multidisciplinary Senior Design

Protocol Communications  SCI protocol (LabView to Master)  3 Pins - Transmit, Receive, Ground  4 Transmissions - 12 Bit Each  1 Start Bit  8 Data Bits(Slave ID, Temp. Bits, Ctrl Bits, etc)  1 Parity Bit (Eliminates Checksum)  2 End Bits 32Project Review RITKGCOE Multidisciplinary Senior Design

Protocol Communications  UART Protocol (Master to Slave)  Bi-directional, half-duplex (only slave or master can talk at one time)  Bit by bit transmission  Different frequencies for ‘ 1 ’ and ‘0’ (in order to meet the 20 ms spec, min. freq = 5kHz; 200 us/bit)  ‘0’ frequency = 7.5 kHz  ‘ 1 ’ frequency = 17.5 kHz  No activity on line = noise only 33Project Review RITKGCOE Multidisciplinary Senior Design

Protocol Communications  40 Bit Transmission  2 Start Bits  6 Checksum Bits  12 Data (temp) Bits  6 Control Bits (read/set, temp/htr state, etc.)  5 Telemetry Pins  8 Bits for Slave ID  1 End Bit 34Project Review RITKGCOE Multidisciplinary Senior Design

Protocol Risk Assessment: Risks  Transfer rate too slow  Not enough bits to account for other details  Bit/error rate too high 35Project Review RITKGCOE Multidisciplinary Senior Design

Protocol Risk Assessment: Actions  Transfer rate too slow  Timing issues between the receiver and transmitter leading to wrong messages being transferred  Not enough bits to account for other details  Not all data will be represented and can lead to a lack of outputting required data  Bit/error rate too high  The wrong message to be transmitted and the appropriate output will not be achieved 36Project Review RITKGCOE Multidisciplinary Senior Design

Protocol Risk Assessment: Mitigation  Transfer rate too slow  Can decrease the time it takes to send a bit  Not enough bits to account for other details  Bits will be added to protocol and the appropriate transfer rates will be calculated.  Bit/error rate too high  Reduction in signal to noise ratio must be changed or an increase in the bandwidth. 37Project Review RITKGCOE Multidisciplinary Senior Design

Protocol Action Items  Acquiring EzDSP  Program the DSP using the FSM flowchart in order to communicate from GUI to Master and Master to Slave  Work with the interface and PWM and ADC programming to ensure proper communication 38Project Review RITKGCOE Multidisciplinary Senior Design

Graphical User Interface Overview  System required a simple computer interface  Needed to be able to control DSP’s and send commands  Easily readable and intuitive  Be able to control multiple parameters  Be able to communicate via Serial Port  Able to control 256 DSP’s Project Review RITKGCOE Multidisciplinary Senior Design 39

Graphical User Interface Risk Assessment: Risks  Time Constraints  Connectivity Problems  Testing, Replication Table  Loopback Testing  Programming Constraints  Final Implementation Requires Working DSP Programming Project Review RITKGCOE Multidisciplinary Senior Design 40

Graphical User Interface Risk Assessment: Actions  Time Constraints  GUI will not get completed  Connectivity Problems  Will not complete GUI to Master Link  Testing, Replication Table  Testing will be more difficult  Loopback Testing  Cannot Initiate Link over Serial  Programming Constraints  Trouble Programming in LabView  Final Implementation Requires Working DSP Programming  Final Product will not be completed in time Project Review RITKGCOE Multidisciplinary Senior Design 41

Graphical User Interface Risk Assessment: Mitigation  Distribution of tasks  Research and Examples  Faculty Help  Purchasing own DSP board  Discussion about final deliverables, removing requirements Project Review RITKGCOE Multidisciplinary Senior Design 42

Graphical User Interface Concept Selection  There were 5 candidates for GUI creation  Visual Basic  LabView  MATLAB  Java  C++  GUI have 5 parameters in which we rated it on  Ease of Use  Safety  Programmability  Customer Preference  Familiarity  A concept selection and screening methods were both used to help determine which method would be best Project Review RITKGCOE Multidisciplinary Senior Design 43

Graphical User Interface Concept Selection Project Review RITKGCOE Multidisciplinary Senior Design 44

Graphical User Interface LabView  LabView was chosen mainly because of its ease of use, and familiarity between the team members  LabView allows us to easily create a nice GUI with multiple features  LabView is also scalable, allows us to add or change features easily without rewriting all of the programming Project Review RITKGCOE Multidisciplinary Senior Design 45

Graphical User Interface Required Features  LabView needs to have visual indicators  Communicate over serial port (RS232)  Ability to see system status  Ability to set and change set points  Ability to chose between 255 slaves to upload temperature Project Review RITKGCOE Multidisciplinary Senior Design 46

Graphical User Interface Front Panel 47Project Review RITKGCOE Multidisciplinary Senior Design

Graphical User Interface Communication 48Project Review RITKGCOE Multidisciplinary Senior Design  LabView will communicate with the Master via RS232  ASCII  Four 12bit transmissions to communicate all data

Graphical User Interface Action Items 49Project Review RITKGCOE Multidisciplinary Senior Design  Complete Replication Table  Replication Table Parameters  Complete Communication Development from GUI to Master  Start Loop-Back Testing