Applications and Implications


Plan and document a final project that integrates the range of units covered.  Here are answers to basic questions...

 What will it do?

I am sticking with my original idea.  A target for kids who want to practice shooting a ball/puck.  This will give children...1) something to aim for when practicing a sport and 2) visual feedback on how they did (e.g. how hard the shot and whether they hit the target).  See my original writeup on how this would work. 

Who's done what beforehand?

I have been looking for different projects that have done similar things.  I've heard of a few projects, but I haven't been able to track them all done.  Here's what I've heard about:

What materials and components will be required?  Where will they come from? How much will it cost?

Here's a list of all parts I will need to complete the project:
    • Eight    6"x6" copper adhesive for sensors
  • Home Depot
    • Two      1"x2'x2' insulation for frame and for tile silicon molds ($5 each..10 total)
    • One      Fiberglass mat and resin ($20)
  • AdaFruit Items to Buy
  • Circuit Specialists
  • RISD Store Items to Buy

What parts and systems will be made?

I am hoping to build this out in many
Tiles: I'll need to make four 6"x6" tiles that will contain the velostat.  They will contain 1/4" silicon cover (for protection) with two pieces of adhesive copper and velostat for the sensors with an LED mounted behind them, which will give students something to aim for. 

Frame: This will have the backing and will be what everything will be mounted to.  The tiles will be at the center of it all.  On the sides there will be two strips of NeoPixel lights to provide feedback.  The back will have all the electronics and wires.  Additionally, the frame needs to be...
- Solid and is going to get hit over and over again by a hard ball/puck (hence having acrylic and/or fiberglass frame. 
- Light...students and teachers need to be able to carry it

Circuit Board (and mount): The brains!  This will be mounted to the back of the board.  Wires will run from the front to the back and will attach in at the headers. 

Stand: I want to make it so this can rest on the ground.  That being the case, I will need to make a detachable stand that will make the target stand up on it's own on the ground (and will be able to take a shot from a ball/pick).  To do this, I am thinking of making it out of composite materials. 

 What questions need to be answered?

  • Which microprocessor should I use
    • Here are the ports I will need to deliver the functionality: 
      • Digital Ports
        • Force LED #1 control connection (must be PORT B)
        • Force LED #2 control connection (must be PORT B)
        • Target LED control connection (must be PORT B)
      • Analog Ports
        • Top left tile sensor
        • Top right tile sensor
        • Bottom left tile sensor
        • Bottom right tile sensor
        • Potentiometer (for setting of difficulty)
      • Programming Pins
        • MISO
        • MOSI
        • SCK
        • REST
      • FTDI PINS
        • TX
        • RX
        • 5V
        • GND
      • Misc PINs
        • AREF: For setting the AtoD reference point
    • Based on conversations with Shawn, we decided I am going with ATMEGA328
  • How much power do I need?  Here is a great writeup on how to power the NeoPixels, which I believe are the major components needing power. But now I need to do the math to determine what will need.  Here's what the writeup says...
To estimate power supply needs, multiply the number of pixels by 20, then divide the result by 1,000 for the “rule of thumb” power supply rating in Amps. Or use 60 (instead of 20) if you want to guarantee an absolute margin of safety for all situations. For example:
60 NeoPixels × 20 mA ÷ 1,000 = 1.2 Amps minimum
60 NeoPixels × 60 mA ÷ 1,000 = 3.6 Amps minimum
The choice of “overhead” in your power supply is up to you. Maximum safety and reliability are achieved with a more generously-sized power supply, and this is what we recommend. Most power supplies can briefly push a little extra current for short periods. Many contain a thermal fuse and will simply shut down if overworked. So they may technically work, but this is the electronics equivalent of abusing a rental car.
In my case, I will have 10 in each force LED strip and four in the target strip (24 total).  Assuming they may be at their brightest, I will assume 60mA.  Here's math...
            24 NeoPixels x 60mA / 1000 = 1.4 Apms minimum
In addition to this, the power consumption of the ATMEGA 328 adds another 7mA (according to this article).

But now I have a problem...a 9v battery only gives off 500mA so I'd need roughly 3 batteries.  I need to dig into whether this will work.
  • Skill Levels:  Should I program in different skill levels that change how hard have to hit in order to get a good score?
    • Based on some conversations with Shawn, we came up with an easy way to set different levels...a 10k potentiometer.  I then added it to version 2 of the circuit board.  Now I need to fine one and figure out how to connect it all into the box. 
  • The Back: How will the stand/back connect and get setup?  
    • I am planning on doing two things...1) setup o-ring screws into the corner so can tie it off on a goal, and 2) setup a stand in the back so that it can rest on the ground.
  • Tile Connection: How will I connect the tiles to the frame? 
    • I am leaning towards glue.  I was worried about whether the glue would cause problems with the conductivity, but Shawn doesn't think it will be a big problem. 

The Plan

Here's the plan with a breakdown of the daily goals and work will need to do...
  • Week of 5/12:
    • Goal: Get frame and circuit boards designed and first drafts built
      • Week:
        • Plan it all out (aka write this document)
        • Design Frame and circuit board
      • Weekend:
        • Get frame and circuit boards milled out at AS220
        • Buy: epoxy, insulation, resin
  • Week of 5/19: 
    • Goal: Get board stuffed and frame put together
      • Monday (AS220):
        • Validate board design and stuff board
          • Need all GND and VCC to connect to one another?
          • Add potentialometer
        • Figure out issues with board and re-mill it (see area next to ATMEGA328)
        • Confirm have everything I need to do 1) composites on back of board (epoxy) on Thursday, 2) copper adhesive
      • Tuesday / Wednesday (home):
        • Design backing that will fiberglass (so is sturdy)
          • Stand
          • Box for circuit board
        • Make changes to the boards/design
          • Frame:
            • Get rid of side holes for straps
            • Move wire holes to more convenient
            • Round corners
          • Mold
            • Move farther away from each other
            • Shrink so are 5 3/4" x 5 3/4"
      • Thursday
        • @ Fay
          • Laser cut box and stand (cardboard first and then go to wood)
          • Check size of backing and angles
        • @ AS220
          • Buy Dragon Skin <- tried, but they had run out.  Will need to use what have and then buy more
          • Re-mill Frame
          • Re-mill molds (out of modela?)
      • Weekend: Sat/Sun/Mon (home): 
        • Paint the frame
        • Fiberglass stand
        • Make silicon part of tile (made half because had no dragon skin)
        • Stuff Draft 2 of board <- stuffed a board and then broke off the traces on FTDI connection...need to do again
  • Week of 5/26:
    • Goal: Put it all together
      • Monday (home)
        • Wire LEDs  <- did half of them
      • Tuesday (as220)
        • Program Arduino
        • Mill out another two boards
        • Get Copper for vinyl cutting at school
      • Wednesday (home):
        • Stuff Draft 3 of board
        • Wire up sensors
        • Test program and connections
      • Tuesday/Wednesday (school)
        • Cut out copper pieces for tiles
        • Cut Velostat so will fit exactly
      • Thursday (AS220):
        • Get help debugging solidering
        • Get programming of ATMega working
        • Buy Dragon Skin <- were all out of Dragon Skin so went with different rubber...
      • Weekend (home): Put it all together
        • Wire up the sensors and get them working
          • Test with old sensor to see if it gives smaller values (this tests that the larger copper isn't making it so there's no resistance)
          • Test with old board and new sensor (see if get other values, and if so, it suggests that the wiring I did is different than the first board)
          • Get analogRefence(External) working
          • Get all tiles working
        • Wire up lights
        • Attach backing to frame
        • Put eye bolts in
      • Monday
        • Do final presentation.png slide
  • Week of 6/2:  Finalize it all
    • Goal: Debug and get it all working

How will this be evaluated?

Goal #1: Provide decent visual feedback
When a ball hits the backing, will it show where was hit and how hard it was hit!  If there is visual feedback that is accurate (e.g. it senses the hit in the right place and it gives a good indication of how hard it was all hit, then goal #1 will be satisfied.

Goal #2: Make it versatile and sturdy
Can the target be easily mounted to a goal?  Can it rest alone on the ground?  Can it take a hit from a ball at 50mph?  This is the second way in which this project should be evaluated.

Goal #3: Does it look cool :->?
I'm not the most artistic guy, but I do want to see if I can make this look pretty cool with different colors, etc.