Adam Harris
FabAcademy Projects

May 14th 2014:   Applications and Implications

The discussion today focused on applications and implications of my final project.

Homework:

This is the final definition set in stone of what my project will do.

Make a page that answers the following:

1. What will it do?

Mimic hand motions.  Accuracy isn't important, I just want to be able to bend a particular finger and have the approximate action mimicked by the robotic hand. Taking Neil's recommendation, I no longer wish to utilize wireless communication.The sensor glove and the robotic hand will be wired together.

2. Who's done what beforehand?

• Open Hand Project
• Shadow Dexterous
• Multiple instructables users like this one
• $200 robotic hand project
• Very cheap robotic hand model
  

3. What materials and components will be required?

•  A store-bought glove
• Flex sensors I will make using tape and conductive bags and conductive thread
•  I will laser cut the hand itself from a piece of 1/16" 3-ply plywood
• Fishing line

• Custom Controller board(s) which require AtTiny chips (or an ATMEGA depending on if the AtTinys don't have enough memory for the communication protocol I implement).

4. Where will they come from?

 I will make everything except the glove and raw components myself.
As for those components, here are some sources for those parts:

• Electrical components: Mouser, Digikey, Newark (Element14), Arrow, any others on Octopart.
• 1/16"Plywood:  Any wood shop will do.  The stuff I used can be found at many hobby stores as well.
• Conductive plastic:  I got mine from Staples.com (this is for the flex sensors)
• Conductive Thread: Online electronics shops have it such as Sparkfun and Adafruit. (For flex sensors)
• Fabric for gloves:  Any fabric store will have some, I tested using burlap from the fabLab inventory (note: burlap makes for terrible gloves...)
• Servos: Again hobby stores. Mine were form FabLab inventory which come from HobbyKing
• Fishing line: Most big box stores sell this, you can also get it at most hunting supplies stores.
• FR1 boards: FabLab inventory.

5. How much will it cost?

• I will buy a cheap glove from a dollar store.
• I already have tape and conductive materials for the flex sensors so they won't cost me anything additionally, but they would only cost a few cents each at most(Likely less than a cent each).
• I built an Arduino Leonardo clone which costs quite a bit.
• Fishing line is free as it comes from a broken fishing pole of mine. I experimented with very thin wire which could be used for free as well (from scrap)
• The wood is stock in the FabLab and doesn't cost more than a few dollars <$3  

Item	Quantity	Price (Subtotal)	Source
Glove	1 (left hand)	$0.50	Dollar Tree store
Gaffers tape	2" thick x 10 ft	$0.13	Source
Conductive	Two 4"x6" bags	$0.43	Source
Masking Tape	12 inches	$0.01	Source
Conductive Thread	50 ft	$8.95	Source
FR1 PCB	One 4" x6"	$0.38	Source
Atmega32u4	1	$4.36	Source
Mini USB Connector	1	$1.05	Source
Button	1	$1.24	Source
ISP Header (2x3 pin)	1	$1.10	Source
Male Headers	16	$0.75	Source
16MHz Crystal	1	$0.96	Source
0.1uF Capacitor	8	$2.72	Source
10pF Capacitor	2	$0.60	Source
0 Ohm SMT Jumper	3	$0.30	Source
22 Ohm Resistor	2	$0.01	Source
499 Ohm Resistor	6	$2.40	Source
680 Ohm Resistor	1	$0.01	Source

TOTAL COST (excluding shipping): $25.09

--I attempted to save costs by making my own glove using fabric int he laser cutter....  This was a huge waste of time and I found that I am no seamstress or tailor.   It was a much better decision to buy a glove when considering my time and budget.

6. What parts and systems will be made?

• I made the controller board in EagleCAD and mill it out on the Modela. Once I populate it, I'll burn the Arduino Leonardo bootloader onto it using the FabISP, then I can program it using the FTDI cable and Arduino IDE.
• I designed the hand itself in Sketchup in 3D, but then moved all of my work to Inkscape.  I changed quite a bit if the project in inkscape directly and then cut it out on the Epilog laser cutter.
• I designed a "grippy" fingertip and 3D printed 5 of them in the Makerbot 2x, I also plan yo mold them in Oomoo by making a mold on the shopbot in machinable wax if time permits.

7. What processes will be used?

• Laser Cutting for the hand
• EagleCAD for designing the PCB
• Modela and Fab modules for milling the PCB
• Arduino IDE or WinAVR for programming the controllers using FabISP
• Makerbot for printing fingertips
• Possibly using the shopbot to make a mold for the Oomoo silicone fingerprints. (I'm using the concept of Spiral Development here...)

8. What tasks need to be completed?

• 1. I couldn't fit all I wanted to into the AtTiny44's memory and didn't have enough I/O pins without having to use the reset line as I/O,thereby preventing me from programming it using ISP, so I'm moving to an arduino Leonardo clone called the FabLeo.
• 2. I need to cut out the final hand design. I've done many iterations and now I need to cut the final version.
• 3. Wiring up the hand with fishing line with knots that won't slip
• 4. Building 5 flex sensors from scratch
• 5. Wiring up the circuitry
• 6. Code, debug, rinse and repeat until finished.

9. What questions need to be answered?

What microcontroller will I use?
Can the AtTiny easily be able to control 5 servos and have an additional 5 analog inputs easily?

Will I have enough time to include casting or molding on this project?
Will Sugru get shipped on time if I chose to use this? ( I haven't placed an order yet).

10. What is the schedule?

As for developing the multiple iterations and debugging code, this project took me about a week's worth of work. That's not all-day-every-day, but I would say at least a good 30-40 hours worth of work total has been devoted to this. Including designing, milling, stuffing, programming and debugging the boards, creating multiple designs for the living hinge and testing different materials on the laser cutter.

If someone wanted to build this project themselves from my files, it shouldn't take more than 2-3 hours to mill, stuff and program the PCB (including tweaking the analog mapping for each flex sensor), laser cut the hand and the glove, create the flex sensors, and have the hand moving around.

11. How will it be evaluated?

• If the corresponding robotic finger moves when on on the glove move (eg, a bend of the index finger in the glove corresponds to a bend in the index finger of the hand, regardless of degree) then I would consider it a success ( grade of C).
  
  
• If it mimics all 4 fingers like the original design indicated, then I would consider that a grade of B.
  
  
• If it can accurately mimic all 5 fingers (including the thumb) well enough to mimic a couple of American sign language symbols fairly accurately, then I would consider that an A+.

• If it can accurately imitate all 5 fingers and I can pick up an object with it, then A+++.