System%20for%20Engine%20Location

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System for Engine Location
Bradley University ECE Department

• Final Presentation for EE 452 Senior Capstone
  Project

• Adam Weintrop and Paul Wimmer Advisors Dr.
  Irwin / Dr. Schertz

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Outline

• Background
• Engine Location Development
• Conclusion

3
Outline

• Background
• Applications
• Previous Work
• Initial Work
• Digital 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

• Background
• Applications
• Previous Work
• Initial Work
• Digital 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 amplifier
• Hardware was disassembled with poor documentation

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Outline

• Background
• Applications
• Previous Work
• Initial Work
• Digital 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

• Background
• Applications
• Previous Work
• Initial Work
• Digital 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 station
• Choose which train to operate
• Choose speed of the train
• Choose 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 Diagram
• Hardware Development
• Hardware / Software Interfacing
• Software Development
• Conclusion

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Overall Block Diagram
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Outline

• Background
• Engine Location Development
• Block Diagram
• Hardware Development
• Hardware / Software Interfacing
• Software Development
• Conclusion

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Train Sensing

• Optical sensing would be illogical
• Numerous sensors
• Train track modification
• Could be helpful for decoupling
• Electrical sensing is practical
• Sensing can be done away from train layout
• Cheaper than optical sensing

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Train Sensing Methods
Cons
Pros
Method
Requires more software and analog multiplexer
Built in the microprocessor board, of trains
8-bit A/D with variable range
Expensive and still requires analog multiplexer
Can determine of trains and of cars
10-bit A/D
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
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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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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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Hardware Schematic
High Gain Amplifier
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Hardware Schematic
Rectifier and Filter D1 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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Hardware Schematic
Comparators Vrun is about 2.75V Vidle is about
260 mV
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Hardware Schematic
Limiting Rlim limits current into diodes and
inverters Diodes limit voltage and HCMOS
inverters provide buffering to rest of digital
circuit Opto-islolators would provide more
protection, but was overkill for this circuit
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Outputs of Hardware (Active Low)
RUN
IDLE
OFF
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Outline

• Background
• Engine Location Development
• Block Diagram
• Hardware Development
• Hardware / Software Interfacing
• Software Development
• Conclusion

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Multiplexing

• 3 - 16 to 4 multiplexer
• All outputs are ORd 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 Diagram
• Hardware Development
• Hardware / Software Interfacing
• Software Development
• Conclusion

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Software Implementation

• Used C code on 80535 because
• Software contains multiple loops to address
  multiplexers
• Software 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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Software Design
Train
Current of Section 1 ltlt Current of Section
2 01?Idle 11?Run Ghost Train
Current of Section 1 Current of Section
2 11?Run 11?Run
Current of Section 1 gtgt Current of Section
2 11?Run 00?Off
Track Section 1
Track Section 2
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Situations

• Ghost Train
• Due 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
Wheres Waldo?
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Flow Chart
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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
RUNNING TRAIN
IDLE TRAIN
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Outline

• Background
• Engine Location Development
• Conclusion

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Outline

• Background
• Engine Location Development
• Conclusion
• Future Considerations
• Current State

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Future Considerations

• Derailed and shorted train allows high current to
  flow
• Software will detect train everywhere rapidly
• Serial 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 Considerations
• Current 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/D
• Analog multiplexing
• But a train with a heavy load could look like a
  faster train

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More Answers

• Nonlinear amplifier?
• More complex than necessary
• Can be substituted for high gain amplifier in
  current system

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More Answers

• Speed and Load Detection
• Difficult 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 Decoupling
• Optical Sensors
• Could place decoupling magnet at edge of track
  section and stop when transition is detected