Project: Seat Sensor System

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Project Seat Sensor System

• Implemented in
• Dinosaur Disneys Animal Kingdom
• Indiana Jones Adventure Disneyland
• Indoors
• Action-adventure ride!

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Presentation outline

• Objective and specifications
• Review original design
• Construction and functional testing
• Design changes
• Performance and reliability testing
• Conclusions

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Objectives

• Detect presence of person and state of seatbelt
• Display output via LED
• State 1 Unlatched and Unoccupied
• State 2 Latched and Occupied
• State 3 Unlatched and Occupied
• State 4 Fault

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Benefits

• Enhance safety features
• Automatically verifies seat occupancy
• Automatically verifies seatbelt state
• Increase hourly ride capacity
• Eliminates need for manual seat check
• Designed around existing ride equipment

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Product Features

• LED indicator
• Counter to keep track of amount of guests
• Affordable safety enhancement
• No additional operators are needed
• Potential for system expansion
• Detect presence of person and state of seatbelt
  while ride is in motion

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Performance Requirements

• Indicates 4 states correctly
• 99.99 reliability
• Implemented with minimal equipment
• Accommodate various weights
• Waterproof and durable

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Original Design

• Block diagram

Vehicle Control System
Control Logic and PLC
Seat Sensors
Guest
Operator LED Display
PLC Display
Seatbelt Sensors
Power Supply
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Design Considerations

• Power conversion 24VDC to 5VDC and back
• Electrode design
• QT310 parameter settings
• Seat belt sensor design
• PLC hardware and software

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Original Design Seat Sensor
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Construction Seat Sensors

• Seat sensors
• Evaluation Board testing
• Circuit construction with custom electrode
• Electrode selection and testing
• Parameter alteration
• Integration

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Power Conversions
Transistor 4.87V to 17V
LM317 28V to 4.87V
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Transistor Output VoltageChoosing the Resistance
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Construction Seat Belt Sensors

• Seat belt sensors
• Hall-effect sensor
• 300 Gauss activation
• Rated 4.75 24V input voltage
• Magnet selection
• Field strength testing

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Programmable Logic Controller (PLC) Signals

• Inputs 24V logic
• 4 inputs for each seat
• QT310 seat sensor
• Seat belt sensor
• Fault
• Reset
• x 2 seats 8 inputs

• Outputs 24V logic
• 4 states for each seat
• Occupied, Latched
• Occupied, Unlatched
• Unoccupied, Unlatched
• Fault
• x 2 seats 8 outputs

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Construction PLC

• Read the manual
• PLC 600 pages
• PLC programming software 300 pages
• DV-1000 Display 200 pages
• Wiring, programming and compilation
• I/O and state testing
• Debug and revise
• Repeat

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PLC Program

• Ladder logic
• Control relays
• Timers
• Counters
• Implements
• State decoder
• Fault detection
• Seat counters

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Construction Integration

• Interface sensors and PLC
• Physical system construction
• Seats and seat belts
• Functionality testing and debugging
• PCB and packaging

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Design Changes Fault

• Original XOR two sensors
• BAD!
• New utilize heartbeat signal
• 15us float superimposed on QT310 output, 20ms
  between beats

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Design Changes Fault

• PLC scan time 20ms.
• Fault signal period 40ms.
• PLC Code
• Timer resets with Fault input.
• If you can count up to 5 fault.
• PCB power outage, fried IC will trigger fault.

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Design Changes

• Electrode
• 24V supply outputs 28V!
• Seatbelt sensors not rated for 28V
• Re-calculation of power conversions
• Counting display
• Added counter for each seat
• Interface with DV-1000 display

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Testing

• Electrode
• Range small enough so as not to detect other
  seats
• Range large enough to accommodate for human
  movement

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Testing

• Seat sensor
• Various weights of humans tested (45kg, 55kg,
  90kg) 50 times each
• Output independent of weight
• 100 reliability
• Various theme park specific objects tested
• Book , backpack, jacket, stuffed animal, water
  bottle, camera, I-Pod, snow globe
• Sensor not activated

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Seat Belt Sensor

• Reliability Testing
• Seat belt outputs 16.7VDC when triggered
• Data over period of 50 trials per seat belt
  yields 100 reliable
• Fulfills performance requirement of triggering at
  least 99.9 of time

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Magnet data
(w,l,t)
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Seat belt Sensor

• Magnet Placement

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Testing Water Tolerance

• 0ml-1000ml in 100ml increments
• Soaked cotton and placed it directly on the seat.
• Up to 3L of water.
• With tub, up to 5L.
• Pass!

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Design Challenges

• PLC programming
• Electrode selection
• Component casualties
• 1 voltage regulator
• 3 QT310 chips
• 1 latch
• 1 resistor
• 1 PLC output module

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Successes

• Met all performance requirements!
• Indicates 4 states correctly
• 99.99 reliability
• Implemented with minimal equipment
• Accommodate various weights
• Waterproof and durable
• Passed all performance tests!

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Recommendations

• Detect seat and state of seat belt while ride is
  in motion
• Transmit outputs wirelessly
• Display outputs on a computer screen instead of
  via LEDs
• Automatic dispatch

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Conclusion

• It works!
• Thanks Mo!
• Thanks Disney!
• Next step
• Present design to Walt Disney Imagineering
• You could be sitting on this one day

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Questions?