Integrated System Build & Test
Meeting Minutes From Previous ReviewDownload
Team Vision for Integrated System Build & Test PhasePhase III Plan: During Phase III the team planned to finalize each of the subsystems. On the mechanical side, we planned to finalize the bottom casing, determine a method to strap the device on the hand, and to finalize an adjustability method. On the electrical side we planned to finish the coding for the main for loop, get all of the letters coded, test non-letter ASCII characters, and test the bluetooth functionality.
Phase III Accomplishments:
Mechanical: A few different methods for adjustability were tested. The first used a chain link, and the second two used pull cord adjusters like those found on backpacks and coats. Both the chain link and the second set of pull cords were successful. The bottom casing was not finalized, but it is very close to being finalized. It was determined that finalizing the adjustability method should be the main priority during this phase. A method to strap the device to the hand still needs to be determined.
Electrical: The main for loop was created as an array of values that are scanned and selected for use and all alphabetic letters are coded. Spacebar and enter are also functional. The device was successfully tested over bluetooth with an iPhone, and “Hello” was typed. The secondary board containing the battery, the teensy, and other components was completed and is functional.
Test Results Summary
|Owner||Test||Ideal Value||Marginal Value||Current Result||Comments|
|Emmanuel||S17: Steps to Take On/Off||Less than 6||8||There are 5 steps needed to put the device on. The steps are done in reverse order (and opposite action) when being taken off.||1. Loosen finger loops and hand/wrist straps. 2. Place device on back of hand. 3. Insert thumb and fingers through appropriate loops. 4. Tie hand/wrist straps to hold device in place. on back of hand. 5. Adjust finger loops to desired level of tension.|
|Nicole||S21: Adjustable||Binary: Yes||N/A||Yes||Will be tested further.|
|Carolyn & Jackie||S6: Finger Flexion||Less than 90 degrees||Less than 100 degrees||15-30 degrees||Further testing will be done to determine the range that is used by each team member depending on the tension that is most comfortable to each member.|
|Emmanuel||S18: Confined to hand/wrist*||Less than 4" past wrist||Less than 5" past wrist||When confined to the hand/wrist area, the device is 2.5" past the wrist.||Confined to wrist and hand. Meets desired value.|
|Emmanuel||S19: Protrudes less than 1" from hand||Less than 1"||Less than 1.5"||Protrudes 5/8" off of the hand.||Meets the desired value.|
|Arshia||S20: Weight of Device||Less than 1 lb||Less than 1.5 lbs||.225 lbs||This only includes the two boards, but we are on track to meet weight requirement.|
Electrical Subsystem Tests
Test 1: PCB Validity [Vibe Motor Test]Upon receiving the PCB and soldering the components to the board, the vibe motor was tested to prove it was soldered and setup properly. A DC source was connected to the vibe motor's pins thereby causing the vibe motor to turn on.
Test 2: BJT Verification [Electrical Validity]An NPN and a PNP BJT circuit was designed in order to test whether or not the power source, and the Arduino's output capabilities were sufficient to illuminate the RGB LED. This was necessary due to the Arduino Teensy's 3.3V maximum voltage output and the power source of 3.7V for the device.
Test 3: Board Continuity Test [Electrical Validity]A protoboard was made to house the battery, charger, Teensy 3.2, bluetooth module, and the rest of the electronics. The board would sense the switches as well as control the motor and RGB LED. The boards were tested for continuity using the multimeter, and then connected using 3-wire servo cables. They were then secured to the table for software testing.
Test 4: Battery Power Test [Electrical Validity]After the PCB had been connected to the protoboard, the power button was tested to ensure that the entire device was able to properly run off of it's own power source.
Mechanical Subsystem Tests
Test 5: Chain Finger Pull Feasibility [Adjustablilty]This test was performed to determine if using a chain for the finger pull was a viable option. We were able to demonstrate all five fingers activating the switch on three different hands. A small clasp was used to adjust the chain length for each finger. A smaller string was used to feed through the activator and then attached to the chain. Small, flexible wire was used to create the rings shown in the video. They proved to be rather uncomfortable for the users because they had to be very tight around the finger. This method required a second person to help adjust the chains. Overall, the method was proven functional, but we decided to explore a different option as well.
Test 6: Cord Lock A
This idea was inspired by the cord locks on a team member’s jacket. We decided that it would be advantageous to incorporate these into the casing to conserve space. During our research on cord lock, we came about a couple different shapes. We decided to use long, cylindrical locks because of their small diameter. We redesigned the base by adding holes in the front of the base to accommodate these. When we put the pieces together, we encountered a couple issues. The spring in the cord lock was not strong enough to hold the string in place when pulled. Feeding the string through the activator just once and tying a knot close to the cord lock seemed to hinder the ability to activate the switch, so we decided to split the end of paracord and thread the ends through. This idea had potential due to how easy it was for the user to adjust, so we decided to explore another cord lock option.
Test 7: Cord Lock BAfter some concern with the paracord slipping through pull cord A, it was determined that it was worthwhile to test pull cord B as the spring stops seemed to have a stronger hold. The base was modified with larger holes to accommodate for the larger diameter of the pull cords. It was determined that the best method for these pull cords was to split the end of the paracord and thread both ends through the activator. This provides for a pull that is well aligned with the switches. The two ends meet and are tied and superglued at the backside of the switch activator. These cord pulls proved to have a stronger hold than the first ones and did not slip when the device is in use. Like the other ones, they still allow for the user to adjust them on his/her own and are very easy to use. One negative to this method is that the cords are a bit uncomfortable on the inside of the fingers, but this can be mitigated through the use of some sort of padding. This will be explored further during the next phase.
Integrated TestAfter getting a case printed with the new cord locks, and working more on some of the software we combined the mechanical system of the switches with the electrical components to be located off the hand, and with the printed PCB with all of the components soldered in. The video shows the device as is can run off of battery power, accept inputs from the switches and send the appropriate character via Bluetooth to a phone. The vibration motor also vibrates to let the user know a character input was detected.
Further debugging is needed to get the LED's functioning properly, but it should not take very long to work out. There is still some work to be done with the code, but nothing major. Additional features like the shift key, and special characters need to be added in but given the proven functionality of the device these should not be difficult to implement.
One change made to the design that was found necessary during the integration of these systems was a pull down resistor for the interrupt pin of the Teensy. The schematic was modified to include small changes such as this as well as to more clearly show which components are currently located on and off of the hand.
Test 8: Weight [Physical Validity]A scale was used to weigh the two boards and connectors, for a total of 102 grams (3.65 oz, or 0.225 lbs). The final housing and other parts still need to be weighed, but the final device is projected to meet the engineering specification for weight.
Risk and Problem Tracking
- Risks can be found here.
- A link to the full problem tracker document can be found here.
Plans for next phase
Download the working document here.
Individual Plans for Phase IV