Week of Nov 18

Meetings

Nov 21

Members present: Dat, Kendrick

A lot was discussed today in a very short amount of time. We finally decided that the servo motors provided in the Sparkfun kit would not be adequate for this project. Although they possess the necessary torque, their range of motion is limited at best. Standard Parallax servos were chosen as good servos to use in this project.

Further work on the Arduino control system was made. Specifically, the RF transmitter/receiver were ordered and the VirtualWire library was explored. VirtualWire would allow us to transmit an array from the transmitter to the receiver. That array could contain the servo angles. As such, we require two Arduinos, one for the robotic hand and one for the human hand.

For next week, the final assembly of the project will be put together. Once the plastic parts have been sent out to be printed, the focus can shift more towards the Arduino system and logistics in terms of how all the electronics will be hooked up.


Nov 19

Members present: Steven, Usama, Kendrick, Dat

Code was quickly written to test and observe the flex sensor as an analog control for the servo motors. There was the issue of whether the servos would be able to rotate enough (the Sparkfun servo range is several degrees less than 0 to 180) and if the $8 Sparkfun flex sensors would suffice. These issues were put on hold for the time being.

The RF transmitter and receiver will be purchased later during the week to be able to test out their capabilities and finalize the Arduino code.

Professor Sullivan gave us the opportunity to have our "knuckle" design printed during the Monday lab session. We were able to obtain them the next day. It only comprises of about 0.04 to 0.09 cubic inches of material, depending on sparse low or sparse high density printing. Some modifications will have to be made before we send a final design to be mass-printed. Shown below is the part that was printed:

Weekly Progress

Dat
Time spent: 4 hours

Redesign of knuckle to allow for use of #4-1/2 inch wood screws to connect to a dowel and #6-3/4 inch panhead machine screw as a pin. Also added a pass through hole for fishing line, which will connect to the last phalange of a given finger and the servo motor, thus closing the finger.

Knuckle5 Part File

Knuckle5 Drawing File

This is the final design for the part, since we would like to have it printed and assembled as quickly as possible.

I also explored the VirtualWire library for Arduino:

VirtualWire Library download and tutorial

Using a pair of RF links (transmitter and receiver at 433 Hz), we can send an array of characters. Essentially we can read in the value from the flex sensor, map that to an array with angle values for the servo motors (0-180), and then convert to characters for wireless transmission via the Arduino function "iota." The code is relatively simple, but will require some experimenting and troubleshooting to get the result that this project requires.

Kendrick
Time spent: 3 hrs

I performed the torque test the past weekend and now have a large DeWalt mechanic's glove. After performing the test, I decided that, while the servos are sufficiently strong to hold the strings and finger, that they are heavily limited with respect to their range of motion. They hardly provide a large enough range to allow the fingers to to clench, so we came to a group decision to order new servos (Parallax standard servos).

I also created the full assembly for a single finger.

Finger Assembly

 

The assembly is made of 3 pairs of knuckles (After the adjusstments were made), 6 single knuckles in total, and three 5/8 inch dowels.

Steven
Time spent:

Usama
Time spent: 5 hrs

Having begun an initial inquiry into the approach I would take with coding the Master Hand, I pursued a pseudocode template and began to explore my options for designing the remote control circuitry and code.

*** [Insert Code] ***


Having designed a systematic flowchart, I then began to explore what options I had for designing the dynamic glove control. Having discussed the ideas with the group, it seemed that there was a great deal of interest in pursuing a wireless option. Having consulted a few external sources, including our T.A. from the Design Lab, Christy, we determined that the Infrared Remote option was going to be complicated enough that it would not be a wise pursuit given our time frame.

As such, I began to explore the RF Transmitter / Receiver route. After browsing through several types, which had differing frequency ranges from 315 to 433 MHz, I settled on a basic 433 MHz RF transmitter / receiver pair and ordered it off of Amazon.com. This particular pair was included in several online tutorials and generally seemed to have good reviews, in spite of its relatively inexpensive price point at approximately five dollars a pair.

I placed the order for the RF Transmitter / Receiver and then conducted some preliminary exploration of the potential code I would need to run the RF Transmitter / Receiver complex. After discussing with Dat what our options were, it became apparent that both of us had discovered the same library for use with the wireless radio communication hardware. The Virtualwire library was an opensource library that contained the code required to run the RF off of the Arduino.

For the week, this seemed like an adequate point to have reached, and I began to plan how I would approach building the code next.