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



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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



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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



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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


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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



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



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



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


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Outline


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


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

Documents

System for Engine Location