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Wheelchair Anti-Theft Device

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Wheelchair Anti-Theft Device

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    1. Wheelchair Anti-Theft Device Final Presentation Sponsored by Walt Disney World, Inc. Group #11 Ed Wahl Gregory Sabounji Ryan Mayer

    2. History of Problem Our objective is to stop guest to guest theft while inside the park Scenario: Guest leaves the unlocked wheelchair near attraction and the wheelchair is stolen by another guest Current Solutions: WDW issues bicycle locks, but the problem is not solved

    3. Abstract Goal: Develop a stand-alone system that will tie a guest to his/her wheelchair Solution: Allow the guest to lock and unlock the wheelchair (easily)

    4. Possible Approaches Proximity Reader User swipes card and chair locks User swipes again and chair unlocks Smart Card Insert card to lock/unlock iButton Touch button to receptor to lock/unlock

    5. Possible Approaches RF Remote Works like a keyless entry system Keypad 4 digit code that must be entered each time to lock/unlock

    6. Issues for Consideration User Responsibility The guest must be able to easily activate the locking device Encumbrance System cannot conflict with the wheelchair’s mobility Durability System must be water resistant and able to withstand temperatures up to 150° F Appearance System must be small and concealed

    7. Issues for Consideration Cost The wheelchairs cost approximately $300 each. An anti-theft device should be reasonably priced in accordance with the value of the chair. Power The system must be able to operate for a full 12-hour day Transportability The wheelchair must still be collapsible for ease of transport/carrying by WDW staff

    8. Solution Proximity Reader Passive – requires no battery in the card Little user responsibility – guest must swipe the card within 3 inches of the reader to lock or unlock the chair Minimal weight/size – will not conflict with wheelchair mobility or collapsibility Programmable –can be programmed to work only with specific proximity card(s) Ease of functionality – for both the wheelchair user and the WDW staff

    9. Design Specifications 12 VDC Powered 7.5 Amp Hour Battery Components current drain of <= 600mA Immobilization of wheelchair Size < 18”x18”x4” Rechargeable Battery Battery monitor – gives some indication of a low battery to prevent “deep discharging” to preserve battery life

    10. Design Specifications Database – allow WDW to monitor what anti-theft devices (and wheelchairs) are in use (checked-out) and remain simple for continuance of the desired short transaction times (~10 sec)

    11. System Design Implementation

    12. System Diagram

    13. System Design International Electronics, Inc. HUB Control Module HID ProxPoint Reader/Interface Board Altronix Linear Power Supply/Charger ELK Lead-Acid Battery Warner Linear Actuator

    14. Front End—Proximity Reader Processes the RF signal from the reader. Sends data to the HUB. Requires 12 VDC. 60 mA current drain. Read range is 2 to 4 inches. Temperature tolerances are –22 to 150 deg F.

    15. HUB Control Unit Requires 12 VDC regulated power Two parts: Relay and Communication board. Relay connects to the “Front End”for control access. Communication board contains RS232 port and Infrared output. Current draw 21 mA typical 51 mA max. Operating temp range 20 to 130 deg F

    16. System Power—Charger Must maintain system with adequate power for 12 hours. Altronix SMP3 Linear Power Supply. Switch selectable 6-12-24 VDC. Filtered regulated output. 2.5 amps continuous current supply 350 mA maximum charge current Built in charger for Lead Acid battery.

    17. System Power—Transformer Revere RT-1640SL Plug-In Transformer Metal Oxide Varistor (MOV) surge protection Primary 120 VAC 60Hz

    18. System Power—Battery 12 V 7.5 Ah Lead Acid

    19. Battery Life Indicator Battery monitor to display the battery life which will serve to notify the WDW staff (and the guest using the wheelchair) if the battery is in need of recharging. The LED will illuminate when voltage falls below level set by R2.

    20. Buzzing Lock Indicator Buzzing (beeping) indicator that signifies that the locking device is being engaged. Relatively low in decibel range (~80 dB) Runs on low voltage and low current (12mA) Withstands temperatures ranging from –20°C to +55°C

    21. Assembly of Components

    23. Locking Mechanism

    24. Actuator The locking mechanism consists of a 60 ft-lb Warner Linear Actuator. The actuator is mounted on the lower and diagonal support beams of the wheelchair using a sheet metal bracket that we fabricated to fit the chair. When the actuator is energized the plunger is extended 1 inch in order to make a contact with the tire of the wheel. This leaves the wheel immobile therefore locking the chair from use.

    25. Actuator When the proximity card is swiped again the polarity of the 12 volts is changed and the actuator releases its force on the tire which in turn unlocks the wheelchair. Actuator Specifications: 12 V. 500 mA 60 ft-lb/sq. inch 1 inch/sec. Speed Max stroke 3 inches

    26. Polarity Switching In order to lock and unlock the wheelchair the actuator needed +12V to lock and –12V to unlock. Accomplished this two different ways. Altronix RBR1224 Ratchet Relay and Altronix timer D-Flip Flop and PC Relay

    27. Polarity Switching D Flip Flop and PC Relay Flip Flop provided 12V every other time to energize the relay coil and change the polarity as shown in figure below

    28. Polarity Switching Altronix RBR1224 Ratchet Relay and Altronix Timer The Ratchet relay reverses the polarity on every pulse from the hub control. The timer relay provides power to the actuator for 1 second.

    29. Polarity Switching Altronix RBR1224 Flip Flop Circuit

    30. Wheelchair Database System

    31. Wheelchair Database System Purpose: To monitor which anti-theft units and wheelchairs have been checked out Functional Requirements: Add (and remove) additional units & wheelchairs to the database Assign checked-out units to their wheelchairs (assignment based on their ID numbers) in the database Release assignment(s) upon check-in

    32. Wheelchair Database System Transaction Scenario:

    33. Wheelchair Database System At checkout: Set the unit and wheelchair checkout flag (“inuse”)

    34. Wheelchair Database System At check-in: Reset the unit and wheelchair checkout flag (“inuse”)

    35. Testing Standby Current 115 mA 7.5 Ah /.115 * 80% = 48.70 hours Active current 620 mA for 1 sec. Worst case with 620 mA on continuously 7.5 Ah / .615 *.80 = 9.76 hours Note : 80% is full discharge to 10 V

    36. Testing

    37. Milestone Chart

    38. Work Distribution

    39. Expenditures

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