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    Wheelchair Progress Notes
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    Wheelchair Progress Notes

    Thursday, 10/10/2019Friday, 10/11/2019Thursday, 10/31/2019Thursday, 11/7/2019gear train idea #1.pngairsoft gearbox.pngThursday, 11/14/2019Sunday, 11/17/2019image.pngThursday, 11/21/2019IMG_0511.jpegIMG_0512.jpegFriday, 11/22/2019Table1Friday, 11/29/2019image.pngimage.pngThursday, 1/2/2020Monday, 1/20/2020image.pngimage.png
    Thursday, 10/10/2019
    ewCame up with Problem Statement for our project:
    ●
    Current wheelchair users face discomfort when sitting down for long periods and strain on their shoulders when controlling the wheelchair.
    Friday, 10/11/2019
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    A pressurized mat that shifts pressure points so the user won’t be stuck in the same posture/position (manual or automatic)
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    Continue with the bike chains and levers
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    Possibly implement different aspects of sports wheelchairs into standard wheelchairs for better finesse and mobility
    Thursday, 10/31/2019
    Look into:
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    Lever arm to gear train ratios with different materials
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    Mechanics of wheelchairs (i.e. torque needed for wheels to move in general)
    Thursday, 11/7/2019
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    Design a method so wheelchair can move backwards as well with the lever system.
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    Have lever attached to a gear train with full freedom of movement and a disc brake to be able to slow down/stop the movement of the wheelchair when needed.
    ○
    Or add mechanism to shift gears but one that determines direction of movement.
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    Ask workshop in the basement of MLK if we can use the laser cutter for metal rods. (Otherwise makerspace)
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    Lever attached to the small wheel, gear on a small wheel attached to a gear on the big wheel. Gear attached on big wheel attached to the center of its wheel with a gear train.
    ○
    Small wheel: 3-4in diameter gear
    ○
    Big wheel: 3-4in diameter gear connected to small wheel gear with a chain. And gear train attached axle on big wheel (gear behind gear for main gear)
    gear train idea #1.png
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    airsoft gearbox.png
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    Thursday, 11/14/2019
    ●
    Scheduled a meeting with Catharin Schweers, an SJSU grad student who's worked on the wheelchair legacy project in the previous year. Going to talk about our current ideas, where they went wrong and how they would've addressed it if they were to work on it.
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    *Note for the team, look into previous year's design and analyze and record what improvements need to be made and what should be kept (also talk with Catharin where they went wrong so we don't make the same mistake).
    Sunday, 11/17/2019
    ●
    design torque wrency type system but with the shaft for lever arm
    ○
    this will allow user to go both ways without a gear chaging system.
    ●
    inorder to do this, mus figure out standard torque wrenches work
    ○
    base it off the ones that give user complete freedom when they want to stop the wrench instead of stopping at fixed forces
    ○
    this allows users to easily switch the direction in which the lever arm moves.
    ●
    disc brakes might not work because that requires a separate assembly.
    ○
    resort to the brakes on the wheelchair itself or stop it by hand.
    ○
    add cantilever brakes to wheels with cables attached on the shaft.
    ■
    task: design CANTILEVER BRAKE, attach it to a rod (role - shaft placeholder in design. once shaft idea is confirmed, design it and make shaft + brake assembly)
    ●
    UPDATE MATERIALS LIST
    ●
    Current Materials list:
    ○
    Spur gears varying in sizes from 4 - 6 inches in diameter.
    ○
    hollow steel/aluminum shafts (40-45 inches long for each side)
    ○
    cantilever brakes and kit (braking handles, cables, etc.)
    ○
    wheelchair
    ○
    torque spring
    ○
    pinion gear for shaft
    Thursday, 11/21/2019
    IMG_0511.jpeg
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    Materials: Sprockets of varying sizes and ratios, bike chains, chain tool, PVC pipes
    IMG_0512.jpeg
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    Materials: handles, U-locks, buts and bolts, bearings, metals sheets, hand tools
    ●
    U-bolts and all materials in Engr221 (potentially, box with all items)
    ●
    Focus on getting a strong foundation/design this year and if it’s a success, continue to prototyping stage for next year
    ●
    Focus on one model of wheelchair to reduce the number of variables we are working with
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    Class 1 device, therefore we can go directly to IRB and get approval for actual testing.
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    Talk with hospitals to see if there are wheelchairs they want to sell for cheap.
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    Ian: worked on ratchet system (torque wrench).
    ●
    Catharin: Bike chain lever system
    ●
    There are already emergrency brakes on wheelchair so adding more is not exactly necessary at this stage of the project.
    Friday, 11/22/2019
    should find industrial pole
    gears in the box in engr221
    Friday, 11/29/2019
    image.png
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    Thursday, 1/2/2020
    ●
    Looked into materials such as Derlin, PLA, Tango+/black/white, and others to get an idea of what material to design the gearbox if printed.
    ●
    Realized a 2 gear system on the big wheel can output enough energy to propel the wheel chair if the chain goes around the big wheel with a little gear to support.
    ○
    The design will still match with previous idea, only difference being the big wheel will have a set up similar above with 1 big gear and 1 small gear while its all connected to a gear with a size in between so it's greater that a 1:1 ratio but smaller than the ratio between the gears set up in the gearbox.
    ●
    Tasks
    design updated model on SolidWorks with more detailed dimensions and reasonable design
    make sure the gearbox has openings for bike chain to cycle through
    connections must work with 1/16" screws to take up as less area as possible while securing the box allowing dust into the gears
    Monday, 1/20/2020
    image.png
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    ●
    Design consists of just the gearbox and aligned gears (details in the technical drawing of exploded view)
    ○
    The holes on the front of the red component is where the bike chain is inserted.
    ●
    Tasks:
    Design component to house the carbon-steel rods and an a way of attatching bike handles to the rods for ease of grip.
    Update gearbox design further to fix it to the big wheel itself

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