System for Engine Location
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Transcript of System for Engine Location
System for Engine Location
Final Presentation for EE 452 Senior Capstone Project
Bradley University ECE Department
Adam Weintrop and Paul Wimmer Advisors: Dr. Irwin / Dr. Schertz
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Outline
Background Engine Location Development Conclusion
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Outline
BackgroundApplicationsPrevious Work Initial WorkDigital Train Control
Engine Location Development Conclusion
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Engine Location
Addition to web train controlled over internet Provide local, instantaneous information
regarding where the engines are and if they are moving
User can see train over internet, but not real time
Avoid train collisions, decouple train cars
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Future Applications At the end of 2-3 years – a fully functional web
train
At the end of ten years – a system for toxic manufacturing automation
At the end of 50 years – a underground mining operation on Mars
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Outline
BackgroundApplicationsPrevious Work Initial WorkDigital Train Control
Engine Location Development Conclusion
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Previous Work
Two previous years have worked on implementing web train
Train has already been laid out Previous work ended in disarray
Over voltages destroyed amplifierHardware was disassembled with poor
documentation
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Outline
BackgroundApplicationsPrevious Work Initial WorkDigital Train Control
Engine Location Development Conclusion
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Initial Work
Majority of time in lab spent trying to operate trains
Train operation manual difficult to implement
Had train enthusiast help us late in the fall to understand and reprogram the train engines
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Outline
BackgroundApplicationsPrevious Work Initial WorkDigital Train Control
Engine Location Development Conclusion
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Digital Command Control
DCC is way of relaying commands to engines
Asynchronous serial communication which includes train identification, command, and error checking
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Standards
DCC Standard
•DCC is based on period length not voltage levels•Allows trains to be self clocking
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Command Station
Menu structure of the command stationChoose which train to operateChoose speed of the trainChoose direction of the train
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H-Bridge
Microcontroller will flip pin to send to H-bridge controlling the track
H-bridge has its direction pin as the input, yielding a unipolar 12V differential output
Input is 5V unipolar differential and makes the H-bridge a good choice
Op Amps only produce a single output or some only produce bipolar output
H-Bridge replaced the broken Lenz LV101 Power Station, a $125 train power supply
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Outline
Background Engine Location Development Conclusion
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Outline
Background Engine Location Development
Block DiagramHardware DevelopmentHardware / Software InterfacingSoftware Development
Conclusion
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Overall Block Diagram
Engine Location System
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Outline
Background Engine Location Development
Block DiagramHardware DevelopmentHardware / Software InterfacingSoftware Development
Conclusion
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Train Sensing
Optical sensing would be illogicalNumerous sensorsTrain track modificationCould be helpful for decoupling
Electrical sensing is practicalSensing can be done away from train layoutCheaper than optical sensing
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Train Sensing Methods
Cannot determine # of trains if trains are at same location and instantaneous speed
“2-bit” method can be designed cheap enough to have the A/D on every track segment, this eliminates analog multiplexers and analog noise
“2-bit” Method
Expensive and still requires analog multiplexer
Can determine # of trains and # of cars
10-bit A/D
Requires more software and analog multiplexer
Built in the microprocessor board, # of trains
8-bit A/D with variable range
ConsProsMethod
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The “2-bit” Method
Three train states are significant in this project
0 0 - Train is off that section 0 1 - Train is stopped at the section 1 1 - Train is running on that section
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R1
R2
DCC
DCC
TRAIN
R3
R4
R5
D1
Rlim
Rlim
D2
D3
U1A
U1BC1
Vrun
Vidle
U2
U3
U4
Bit 1
Bit 0
Hardware Schematic
Transformer
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Current Sensors
Current changes with train presence and can be detected away from physical track
Resistor was used first Did not isolate the train supply circuit from rest of system Large values barred sufficient train current, small values did not
produce adequate sensing voltage Transformer
Isolates the detection and train circuits Voltage is independent of energy drawn from train circuit
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R1
R2
DCC
DCC
TRAIN
R3
R4
R5
D1
Rlim
Rlim
D2
D3
U1A
U1BC1
Vrun
Vidle
U2
U3
U4
Bit 1
Bit 0
Hardware Schematic
High Gain Amplifier
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R1
R2
DCC
DCC
TRAIN
R3
R4
R5
D1
Rlim
Rlim
D2
D3
U1A
U1BC1
Vrun
Vidle
U2
U3
U4
Bit 1
Bit 0
Hardware Schematic
Rectifier and FilterD1 is half wave rectifier
R3,C1,R4 form filter
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Rectifier and Filter
Diode rectifies voltage Filter cutoff frequency
Wanted DC, filter response became too slow Affects entering and exiting trains – “Ghost Train”
Too high of cutoff induces intermittent “Ghost Sightings”
340 Hz was found after experimentation to be a good balance between speed and bandwidth
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R1
R2
DCC
DCC
TRAIN
R3
R4
R5
D1
Rlim
Rlim
D2
D3
U1A
U1BC1
Vrun
Vidle
U2
U3
U4
Bit 1
Bit 0
Hardware Schematic
ComparatorsVrun is about 2.75V
Vidle is about 260 mV
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R1
R2
DCC
DCC
TRAIN
R3
R4
R5
D1
Rlim
Rlim
D2
D3
U1A
U1BC1
Vrun
Vidle
U2
U3
U4
Bit 1
Bit 0
Hardware Schematic
LimitingRlim limits current into diodes and inverters
Diodes limit voltage and HCMOS inverters provide buffering to rest of digital circuitOpto-islolators would provide more protection, but was overkill for this circuit
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Outputs of Hardware (Active Low)RUN
OFFIDLE
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Outline
Background Engine Location Development
Block DiagramHardware DevelopmentHardware / Software InterfacingSoftware Development
Conclusion
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Multiplexing
3 - 16 to 4 multiplexer All outputs are OR’d together to combine to have
4 total outputs at one time Select lines are the same for all chips With different chip enable pins on each
multiplexer Can sense 2 track sections at a time This can free up several I/O lines to the
microprocessor
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Outline
Background Engine Location Development
Block DiagramHardware DevelopmentHardware / Software InterfacingSoftware Development
Conclusion
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Software Implementation
Used C code on 80535 becauseSoftware contains multiple loops to address
multiplexersSoftware execution time was not an issue for
our system Desire to learn embedded C
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Software Plan
Want to take information of train status and location and process
Hardware outputs are numerous, need to be sorted
Output where train is and status First step to more advanced software
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Track Section 1 Track Section 2
Software Design
Current of Section 1 >> Current of Section 2“11”Run “00”Off
Current of Section 1 = Current of Section 2“11”Run “11”Run
Current of Section 1 << Current of Section 2“01”Idle “11”Run“Ghost Train”
Train
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Situations
Ghost TrainDue to time constant of hardware, voltage
does not fall rapidly Idle train is detected where previously running“Boo!” Software removes ghost trains
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Software Development
Where’s Waldo?
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Flow ChartSelect the MUX chip enable and
select inputs
Check run bits (by selecting various
select inputs)
Check idle bits (by selecting various
select inputs)
Determine the location of the running train(s)
Determine the location of the idle
train(s)
Ignore idle trains that are also
running
Check for and igrore any “Ghost
trains”
Send train location and status information
through a serial port
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Serial Communication
Microcontroller will send via serial port train information
Receive software on PC written in MATLAB and displays colors on track layout image
MATLAB was chosen for its easy to use serial and graphic libraries
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Serial Receive
IDLE TRAIN RUNNING TRAIN
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Outline
Background Engine Location Development Conclusion
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Outline
Background Engine Location Development Conclusion
Future ConsiderationsCurrent State
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Future Considerations
Derailed and shorted train allows high current to flowSoftware will detect train everywhere rapidlySerial port buffer fills causing delays in display
Display could have direction, speed, distance added
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Outline
Background Engine Location Development Conclusion
Future ConsiderationsCurrent State
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Conclusion
Locates up to 2 engines and displays on PC Low-cost system Easily installed and adaptable to other train systems System is readily expandable to support future projects Questions?
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Questions? – We have answers
A/D method?Need precise A/DAnalog multiplexingBut a train with a heavy load could look like a
faster train
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More Answers
Nonlinear amplifier?More complex than necessaryCan be substituted for high gain amplifier in
current system
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More Answers
Speed and Load DetectionDifficult without more accurate sampling
method A fast train could be confused with a heavily
loaded train
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More Answers
Precision location for DecouplingOptical SensorsCould place decoupling magnet at edge of
track section and stop when transition is detected