Upload
ania
View
56
Download
0
Tags:
Embed Size (px)
DESCRIPTION
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 - PowerPoint PPT Presentation
Citation preview
P09141Satellite Thermal Heater Controller
Anthony Berwin Mechanical Engineer
Scott Rioux Industrial Engineer Greg Pawlowski Electrical Engineer Sarmad Abedin Electrical EngineerJohn Scipione Electrical
Engineer
Sponsors: ITT Corporation & D3 Engineering
1 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Milestones MSD 1
January 16, 2009 – System Level Design Review February 13, 2009 – Detailed Design Review February 20, 2009 – MSD I Review Presentation
MSD II May 2, 2009 – Poster Session I May 15, 2009 – Technical Paper May 15, 2009 – MSD II Review Presentation May 19, 2009 – Demonstration May 22, 2009 – Poster Session II
Project Review R•I•TKGCOE Multidisciplinary Senior Design
2
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
3 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Project Sections Enclosure Graphical User Interface PC to Master Communication Master to Slaves Communication
4 Project Review R•I•TKGCOE Multidisciplinary Senior Design
EnclosureNeeds & Specifications Material (6061 Aluminum Alloy, 316 Stainless
Steel) Size (Minimize) Mass (<0.450 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)5 Project Review R•I•TKGCOE Multidisciplinary Senior
Design
EnclosureAssembly Model
6 Project Review R•I•TKGCOE Multidisciplinary Senior Design
EnclosureAssembly Model: Exploded View
7 Project Review R•I•TKGCOE Multidisciplinary Senior Design
EnclosureSpecifications Met Material:
6061-T6511 Aluminum Alloy (Top & Bottom Parts) Type 316 Stainless Steel (Machine Screws)
Total Size: 3.50” x 2.875” x 1.00” Size of the PCB with the Accelerometer: 3.0” x
2.0” x 0.563” Total Mass: 0.4317 lb
4.06% below the 0.450 lb limit Enclosure Mounting:
Flat Plate & Cylinder (R > 18”), dmax < 3/32” PCB Mounting:
Five (5) 2-56 Machine Screws8 Project Review R•I•TKGCOE Multidisciplinary Senior
Design
EnclosureSpecifications Not Met Partially Met
Connector Mounting Vacuum Environment
Ventilation Outgassing
Not Met Torque on Screws EMI Leakage
9 Project Review R•I•TKGCOE Multidisciplinary Senior Design
EnclosureDesign Analysis: Strengths & Weaknesses Strengths
Scalable to Varying Sizes of the PCB Easy to Machine Two (2) Pieces Low Cost of Materials Easily Assembled
Weaknesses Excess Weight
1/8” thickness for machining Connector Mounting
Mating connectors are not secured
10 Project Review R•I•TKGCOE Multidisciplinary Senior Design
EnclosureDesign Analysis: Potential Improvements
Decrease Weight Decrease the thickness to 1/16” or 3/32” from 1/8” Change the strew type from 4-40 to 2-56
Connector Mounting Add component to secure mating connectors
Account for Ventilation Add ventilation slot
Account for EMI Leakage Minimum thickness
Account for the Torque on Screws Verify minimum screw type
11 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Graphical User InterfaceOverview 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 R•I•TKGCOE Multidisciplinary Senior Design
12
Graphical User InterfaceLabView 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 R•I•TKGCOE Multidisciplinary Senior Design
13
Graphical User InterfaceSpecifications Communicate over serial port (RS232) Ability to see heater state status and
telemetry information Ability to set and change temperature set
points Ability to chose between 255 slaves to upload
temperature
Project Review R•I•TKGCOE Multidisciplinary Senior Design
14
Graphical User InterfaceProgramming Programming started with communication
over serial Building blocks for the project were added on
top Each requirement or functionality that was
needed was researched then implemented Problems that arose were quickly dealt with by
research
Project Review R•I•TKGCOE Multidisciplinary Senior Design
15
Graphical User InterfaceProgramming/Development Message Creation
Messages were created using loops and numerical to string identifiers.
Labview sends out 24 bits, which gets converted to 3 ASCII characters
Message Contents Message contains all elements needed to
communicate with DSP Slave ID gets transmitted first, control bits 2nd, and
temperature last The control bits relate to controls on the front panel
that allow the user to manipulate the message and retrieve different data
Project Review R•I•TKGCOE Multidisciplinary Senior Design
16
Graphical User InterfaceProgramming/Development
Project Review R•I•TKGCOE Multidisciplinary Senior Design
17
Structures All Labview programming is grouped within loop
structures so data and set points can be updated continuously.
Different structures exist for different functionality. Initialization of slaves, Continuous message
sending, Message building Some key building blocks are : Steinhart-Hart
function, Binary number creation, Voltage readings, Serial port open/close
Graphical User InterfaceFront Panel
18 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Graphical User InterfaceSpecs Met/ Not Met
19 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Met Ability to communicate over serial Ability to send and receive data from DSP Ability to control temperature and control bits Has visual indicators
Not Met Simplicity of GUI
Graphical User InterfaceStrengths/Weaknesses
20 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Strengths Very Powerful Has lots of Error Checking and Debugging Easily Understood
Weaknesses Computer resource intensive Complex changes take time
Graphical User InterfacePotential Improvements
21 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Improvements Make front panel more visually appealing Revise and improve looping Create simpler ways to do programming
CommunicationsOverview
22 Project Review R•I•TKGCOE Multidisciplinary Senior Design
PC to Master Communications Overview Communication between Master DSP and
Graphical User Interface (GUI) must occur over SCI Protocol must be able to incorporate the many
needs of the User Master must generate a new message for the
‘slave’ DSPs after receiving a message from GUI. After receiving a response from the appropriate
slave, the master DSP must generate a new message to send back to GUI
23 Project Review R•I•TKGCOE Multidisciplinary Senior Design
PC to Master Communications SCI Protocol SCI protocol (LabView to Master)
3 Pins - Transmit, Receive, Ground 3 Transmissions - 12 Bit Each 1 Start Bit 8 Data Bits(Slave ID, Temp. Bits, and Ctrl Bits) 1 Parity Bit (Eliminates Checksum) 2 End Bits
24 Project Review R•I•TKGCOE Multidisciplinary Senior Design
PC to Master Communications Objectives The SCI message was received and transmitted
back using an interrupt routine using the RX buffer and TX buffer in the EzDSP.
A circular buffer routine was utilized to prevent overriding incoming messages from LabView.
The Master to DSP message also included five telemetry pins, mainly used for debugging.
Messages from LabView were appended to include start bits, transmit/receive bit, error bit, and check sum bits.
25 Project Review R•I•TKGCOE Multidisciplinary Senior Design
PC to Master Communications Specifications Met/Unmet Specs Met
Ability to communicate from/to GUI via serial port Ability to communicate to/from the slaves and to
retrieve information from the HHC The use of an interrupt service routine for
transmitting and receiving Unmet Specs
20ms total communication time
26 Project Review R•I•TKGCOE Multidisciplinary Senior Design
PC to Master Communications Strengths and Weaknesses Strengths
The user can continuously ask the master to report data from any particular slave and see it updating in real time.
The protocol is reliably able to handle all of the user’s needs.
Weaknesses Cannot guarantee a complete and/or correct
message is sent all the time because of SCI TCP for example, has the ability to automatically
resend messages to ensure proper transmission to the receiver.
27 Project Review R•I•TKGCOE Multidisciplinary Senior Design
PC to Master CommunicationsPotential Improvements A more reliable protocol instead of SCI
In order to better handle errors and ensure proper transmission
28 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Master to Slave CommunicationNeeds Master DSP communicates with up to 256
slaves over the heater power bus. No dedicated communication lines are used.
One master, multiple slave design. DSPs communicate by a half-duplex BFSK
technique.
29 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Master to Slave Communication Modulation/Demodulation A sine wave is generated from a binary string
using the HRPWM and a passive low pass filter.
The sine wave is transmitted over the DC power bus.
The sine wave is then demodulated back into binary using the ADC with a digital filter.
The Goertzel Algorithm was used to implement the digital filter.
30 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Master to Slave CommunicationProtocol BFSK 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 = 62.5 kHz ‘1’ frequency = 78 kHz No activity on line means no signal
31 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Master to Slave Communication Protocol 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
32 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Master to Slave Communication Interface Electronics Coupling transformer to couple to AC and DC
components. Capacitor along with transformer used to
create a high pass filter. Allows us to create a sine wave on power bus
without disturbing the operation of the heaters.
33 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Master to Slave Communication Strengths and Weaknesses Strengths
Used software techniques in the DSP to do the modulation and demodulation rather than using external hardware.
Flexible: different frequency/bandwidth combinations possible.
Weaknesses Each slave added creates a parallel resistance so
a larger and larger signal is needed for each slave added.
We don’t check to see if a message is good until a complete message is received.
Half Duplex only, can only send or receive at one time.
Reliability could be improved.34 Project Review R•I•TKGCOE Multidisciplinary Senior
Design
Master to Slave Communication Specifications Master to slave communication time 20ms
Did not meet, actual communication time ~200ms
Bandwidth < 300KHz Met, Bandwidth < 90Khz
Bit error rate 1e-6 Did not meet, ber undermined but higher than
1e-6 Signal to noise ratio -40db
Did not meet, snr is around 10db Amplitude < 10mVpp
Did not meet, Amplitude ~ 1Vpp35 Project Review R•I•TKGCOE Multidisciplinary Senior Design
Master to Slave Communication How could these be improved? Master to slave communication time 20ms
Reduce code size by splitting up master and slave code
Used external hardware to generate and detect sine wave
Bit error rate 1e-6 Improve synchronization between master and
slave Goertzel. Signal to noise ratio -40db
Longer transmissions per bit, raise the bandwidth
Amplitude < 10mVpp Output smaller signal and then amplify it36 Project Review R•I•TKGCOE Multidisciplinary Senior
Design
Closing Comments Special Thanks
Margaret Bailey, Jerome Barczykowski, Sohail Dianat, Christopher Hoople, Marca Lam, Chuck Moon, Jay Radhakrishnan, Scott Reardon, George Slack, Perry Voyer, Christianna Walter and John Wellin
Questions and/or Comments
Project Review R•I•TKGCOE Multidisciplinary Senior Design
37