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System for Engine Location

Bradley University ECE Department. System for Engine Location. Adam Weintrop and Paul Wimmer Advisors: Dr. Irwin / Dr. Schertz. Final Presentation for EE 452 Senior Capstone Project. Outline. Background Engine Location Development Conclusion. Outline. Background Applications

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System for Engine Location

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  1. Bradley University ECE Department System for Engine Location Adam Weintrop and Paul Wimmer Advisors: Dr. Irwin / Dr. Schertz Final Presentation for EE 452 Senior Capstone Project

  2. Outline • Background • Engine Location Development • Conclusion

  3. Outline • Background • Applications • Previous Work • Initial Work • Digital Train Control • Engine Location Development • Conclusion

  4. 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

  5. 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

  6. Outline • Background • Applications • Previous Work • Initial Work • Digital Train Control • Engine Location Development • Conclusion

  7. 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

  8. Outline • Background • Applications • Previous Work • Initial Work • Digital Train Control • Engine Location Development • Conclusion

  9. 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

  10. Outline • Background • Applications • Previous Work • Initial Work • Digital Train Control • Engine Location Development • Conclusion

  11. Digital Command Control • DCC is way of relaying commands to engines • Asynchronous serial communication which includes train identification, command, and error checking

  12. Standards DCC Standard • DCC is based on period length not voltage levels • Allows trains to be self clocking

  13. Command Station • Menu structure of the command station • Choose which train to operate • Choose speed of the train • Choose direction of the train

  14. 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

  15. Outline • Background • Engine Location Development • Conclusion

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

  17. Overall Block Diagram

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

  19. 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

  20. Train Sensing Methods Method Pros Cons 8-bit A/D with variable range Built in the microprocessor board, # of trains Requires more software and analog multiplexer 10-bit A/D Can determine # of trains and # of cars Expensive and still requires analog multiplexer “2-bit” Method “2-bit” method can be designed cheap enough to have the A/D on every track segment, this eliminates analog multiplexers and analog noise Cannot determine # of trains if trains are at same location and instantaneous speed

  21. 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

  22. Hardware Schematic Transformer

  23. 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

  24. Hardware Schematic High Gain Amplifier

  25. Hardware Schematic Rectifier and Filter D1 is half wave rectifier R3,C1,R4 form filter

  26. 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

  27. Hardware Schematic Comparators Vrun is about 2.75V Vidle is about 260 mV

  28. 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

  29. Outputs of Hardware (Active Low) RUN IDLE OFF

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

  31. 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

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

  33. 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

  34. 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

  35. Software Design Train Current of Section 1 << 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 >> Current of Section 2 “11”Run “00”Off Track Section 1 Track Section 2

  36. 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

  37. Software Development Where’s Waldo?

  38. Flow Chart

  39. 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

  40. Serial Receive RUNNING TRAIN IDLE TRAIN

  41. Outline • Background • Engine Location Development • Conclusion

  42. Outline • Background • Engine Location Development • Conclusion • Future Considerations • Current State

  43. 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

  44. Outline • Background • Engine Location Development • Conclusion • Future Considerations • Current State

  45. 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?

  46. 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

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

  48. More Answers • Speed and Load Detection • Difficult without more accurate sampling method • A fast train could be confused with a heavily loaded train

  49. More Answers • Precision location for Decoupling • Optical Sensors • Could place decoupling magnet at edge of track section and stop when transition is detected

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