TF: Group Project- The Trust T-shirt

At first our group brainstormed many ideas until eventually deciding that we wanted to use a blindfold to take away someone’s sense of sight, then use our project to guide them. This is how the project would work:

  1. Person A wears a blindfold to augment their sense of sight
  2. Person B uses a flashlight to guide person A
  3. We design a T-shirt for Person A which would contain two light sensors (one to the right of the chest and one to the left of the chest), which would detect Person B’s flashlight cue. Depending on what cue is sent, a vibration motor corresponding to the side of the sensor would vibrate
  4. If person B aims the flashlight to the right sided sensor a vibration motor (on the right side of the shirt) would be activated indicating that person A should turn right and vice versa.

After thinking about functionality a bit more, we noticed that placing the light sensors on the front of the shirt would be a bit awkward, especially as the leader would have to walk backward to guide the follower.

We thought that placing the sensors on the back of the follower’s shirt would be much more practical and so we moved ahead with that idea.

Next, we prototyped the basics. We created our circuit using a breadboard and Arduino. You can find a rough sketch of the circuit below.

Next we experimented with the code and thankfully it worked. We tried the following code for the LDR, declaring them as the inputs and giving them a range of light to detect:

int sensorPin = A0; // select the input pin for LDR

int sensorValue = 0; // variable to store the value coming from the sensor

void setup() {

Serial.begin(9600); //sets serial port for communication

}

void loop() {

sensorValue = analogRead(sensorPin); // read the value from the sensor

Serial.println(sensorValue); //prints the values coming from the sensor on the screen

delay(100);

}

 

For the motor we used this code, declaring them as the outputs:

const int motorPin = 9;

void setup(){

pinMode(motorPin, OUTPUT);

}

void loop(){

digitalWrite(motorPin, HIGH);

delay(1000);

digitalWrite(motorPin, LOW);

delay(59000);

}

We then tested to see if these worked by shining light on each sensor and monitoring whether the corresponding motor vibrated. Since this worked, we proceeded to think about how we could make a more compact circuit to be placed onto a T-shirt, so that it could be wearable.

We decided to move all the components onto a lilipad which could be sewn onto fabric. However, before moving any circuit onto a lilipad, it was important to carefully plan how this would be done. We found sketching very helpful. You can find a picture of the sketch below.

We started by couching ground on the Lillipad to a white piece of cotton fabric. From there we did a backward stitch leading a looped piece of wire. We couched one side to ground. On the other side, we would use conductive thread to sew two separate branches which would then connect to each of the two 10 ohm resistors needed for the LDRs. Using wires and conductive thread, we sewed these components to a1 and a2 respectively.

 

We did the same procedure for the 5V, starting with one wore which would then branch out into two parts for the left-sided LDR and the right-sided LDR. The other side of the LDR would then connect with the resistor branches at a1 and a2 respectively.

The motors were connected to the circuit via pins 6 and pins 13. For the left-sided motor, one of its wires connected to pin 6, while the other side was rejoined to the first branch created at ground. The same was done for the right-sided motor, with one end connected to pin 13 and the other joining the other wire branch at ground.

A picture of the final outcome could be found below. The LDRs are at the bottom and the motors are at the sides, just slightly above the LDRs.

After this process, we secured the white cotton fabric onto the t-shirt using double-sided tape. We also spent a substantial amount of time securing all connections. We used nail polish remover to secure frayed ends of conductive thread and electrical tape to insulate any wires which were twirled around each other. We then couched the motors onto the back of the shirt and created small holes in the t-shirt for the LDRs to peek through. Finally we had a working product.

We left our finished project over the weekend, then returned to it on Monday to meet a fully functioning project. However, by Tuesday, when we had to present, we noticed that the left-sided motor did not work. While troubleshooting the problem, we noticed that when we aimed light at the LDR, it started returning absurd values to the serial monitor. It was evident that the LDR broke. Soon after, the right-sided LDR and motor, which was still working also stopped. The LDR returned normal values, but while checking the connections, we noticed that one of the tiny, delicate wires which came attached to the motor became disconnected. This happened while we were flipping the shirt inside and out to rectify the issue with the left-sided motor. This was an unfortunate turn of events at the 11th hour. However, one must always be prepared for such troubles and take videos and pictures of  the working project at every step of the way. Thankfully, we had one short video of the working product which you can find below.

Click here for working T-shirt Link

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