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Looking for general tips, unique project

  1. Dec 22, 2015 #1
    Hi, I have 0 background in engineering nor robotics. I have a project requiring both, so if you can help at all or give good feedback that would be very appreciated.

    The true reason behind my project is a bit secretive for me, purely because I think it’s a smart idea and I don’t want the idea getting out there until it’s complete. So, for the purposes of this thread, I will fabricate the purpose of the project (yet the mechanics will be EXACTLY the same necessary for the true intent).

    Purpose: Create an “eye test” that hangs on the wall which demonstrates what it’s like to see it with sharp vision, and then blurry vision (without the influence of eye glasses or lenses). The text that is on the poster hanging on the wall will fluctuate randomly from sharp and blurry, with all 4 corners working together to produce this effect, which will actually even allow certain sections of the poster to be sharp and others blurry.


    The poster hanging on the wall will have text on it. In front of the poster, drilled into a frame that surrounds it, will be a sheet of non reflective plexiglass, where if moved a few inches away from the image, the image becomes blurry. Likewise, if the plexiglass is right up against the image, the imagine is 100% sharp; the further away, the more blurry. So basically, we’re using non reflective plexiglass to blur the text behind it.

    My idea for implementation:

    4 screws hold the four corners of the plexiglass suspended in front of the “seeing eye” poster. These 4 screws are drilled into a frame around the poster, and BEHIND the frames/poster is where the magic happens. Put differently: The viewer doesn’t see any of the mechanics actually moving things around. Nice! right??

    Doing some preliminary internet research, it would seem the simplest way to achieve this is to hook up the screw to a stepper motor. As the 4 stepper motors (one on each corner) rotates either forward or reverse, the screw then moves up or down, which is thus either moving that given corner of plexiglass either up or down (controlling the level of blur in the poster).

    So say for example I want full blur, the stepper motor rotates forward to a maximum position on all four corners. If I want just the left top corner sharp and the rest of the angles more blurry, I’d reverse motion the top left corner stepper motor and leave the others at maximum position.

    HOPEFULLY this makes sense so far :(

    How in the world is the stepper motor moving a screw up and down? Well through this sort of device (excuse my poor vocabulary here): https://www.google.com/search?q=rob...h&q=motor+differentials&imgrc=D-6Co1ooAV_XOM:

    Basically just attach some sort of grid on the bottom of the screw underneath the poster to line up to another rotational device with the same type of physical pattern, and THAT device is hooked up to the stepper motor. Shouldn’t be too complex. Just using rotation set up with “connectors.” Just will require some rigging.

    What gets a bit more complex, is then all four motors have to be wired to some type of computer chip that does the following: Every 5 seconds VERY SLOWLY and VERY SILENTLY shift to 4 random pre set screw heights. In other words, for example position number 1 will be with bottom left corner at lowest screw position (image sharp), and everything else at highest position. Then, position two will simply be the whole thing blurry (max screw height on all corners). Etc etc.

    SO, wrapping this up, the general idea is that when power is ON for the device, the computer behind the poster is sending out the random 4 preset coordinates to the four corners, and likewise very slowly the “eye test” is shifting in front of the viewer. Showing them what it’s like to have blurry vision on the left side for example, or everything blurry, or everything sharp. The illusion will be moving very slowly, and silently.

    ANY feedback on how to get this done is appreciated. I have seen that there are types of DIY chips out there that you can plug into a USB and program to do certain things, which might be the route I have to go down. No clue how to code it. I feel like the code isn’t insanely complex though.

    *An additional complication, I’d ideally like users to set the hours of the day they’d like this device to remain ON, via a clock like display. For ex, on the bottom of the frame is a clock where user can set the time range of day the system is running, and it will turn off once the time has exited that range. (likewise it would be good for the user to be able to set the current time). Honestly, that part is less essential at least right now. The temporary simple alternative is just an ON OFF button.

    A concern of mine: How will it be powered? Well I’d really like it to be battery powered, with the battery behind the poster. Bit of a drag having a ugly looking cord running along the wall. BUT, I’ve heard stepper motors are a lot more power hungry than DC motors, and also adding a chip, battery might not be an option. :(

    Any links you can provide for devices you suggest, products, anything is appreciated. I’m still at the knowledge phase.

    The project is going to be worth it. Wish I could share what it’s actually going to be for, but I can’t yet ;0
    I will at some point though!

    Really appreciate anyone who has actually read all of this!
  2. jcsd
  3. Dec 22, 2015 #2


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    What are the scales of this project? Size of the image, price range?

    Is the whole blurry picture a relevant part of the project? I see some issues with it, but I'm not sure if it is relevant.

    Where is the point in the mechanics behind the picture? You can directly attach a stepper motor to the screw.

    Concerning the controller: a Raspberry Pi gives you a proper computer, which should be easy to set up. Costs are negligible, power consumption is of the order of 1 W. An Arduino needs a bit more thought to program, but you get power consumption down to 100 mW, maybe even lower as the device does nothing most of the time. Power consumption of the motors will depend on the size of the project (see above) and other details.

    If the whole thing is small, a display showing a video could be cheaper.
  4. Dec 23, 2015 #3
    Thanks for the response,

    Ideally, this project should be able to work for a small work, or a large work...like 12 feet. However, for at least getting an initial work going, I'll just do it on a small piece. 24''x12'' or something.

    The blurry picture is very important, the whole point is for the image to be able to get this effect.

    Thank you for the suggestions. A video would be cheaper, but this has to be a real thing. A real physical product.
  5. Dec 24, 2015 #4


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    The problem with blur: we react highly nonlinear to blur. "2 times more blurry" doesn't make a large difference, compared to the difference between "completely sharp" and "a bit blurry".
    If some edges are set to blurry, the whole image apart from tiny edge or corner regions will appear significantly blurry in various degrees.

    The glass would have to bend, and bending plexiglass could be ... problematic.
  6. Dec 26, 2015 #5


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    Can you do this with image processing instead of moving plexiglass? For example, display the image text on an LCD panel and just process different parts so they look blurred?
  7. Dec 26, 2015 #6


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    Does the plexiglass have to be in front of the poster? If the poster can't be an LCD panel can you do it with a back projector and image processing?
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