Brainstorming Team Members: Advay Mahajan, Stella Nantale, Antonella Amaral, Camilo Londono
The brainstorming had the falling semester goals this semester:
- We will start brainstorming different ways to measure stress. After finding different metrics of stress, we will pick one or two and start brainstorming devices for those metrics. At the end of the phase, we will create a decision matrix and narrow our devices down to one.
- Then, we enter the next phase which is a mathematical modelling phase. In this phase, we create an algorithm that will convert a potential sensor value from a sensor we are using, and convert it into usable data. Since none of us are CS majors and most people working in this team have little device experience, this phase should take around three weeks.
- The next phase is the prototyping phase, which will last the remainder of the semester. In this phase, we (or whoever is on campus) will either make the actual device or plan out everything about the actual device including circuitry and Arduino code.
This semester, we accomplished all of these goals.
After conducting research on various metrics of stress, we each picked a metric and created two concept drawings each on a potential device. The concept drawing did not need to be an exact representation of what the actual device would look like, it just needed to get the basics on how it would be connected to the Arduino and where it would go on the human body. Here are the different drawings that people drew below.
After we created these concepts, the next step was to narrow our designs from 8 to 1 design to focus on. We did this through the help of a decision matrix. In this decision matrix, we picked a variety of criteria to judge each device on. We would award each device a score from 1-10 on each category with 1 being the worst and 10 being the best. Additionally, each category does not carry the same importance as others. Therefore, since there were nine categories, we rated the most important category as 9 and the least important category as 1. We multiply each score in the category by the category weightage and sum up all these values. The device with the highest score is the device most ideal to develop. The decision matric is below.
Thus, since temperature sensor of the underarm had the highest score, we chose to take that device further. The next step was the creation of a mathematical model. After much research we found a special algorithm which helps us out a lot.
The Steinhart and Hart Equation is an empirical expression that has been determined to be the best mathematical expression for resistance temperature relationship of thermistors.
T” is in degrees Kelvin and “A”, “B”, and “C” are coefficients. resistance is known and temperature desired use this equation. Knowing A, B and C for a thermistor allows you to use the Steinhart and Hart equation. After finding this algorithm, it was time to start the third phase: the prototyping phase. Since we chose to meet virtually, instead of making an actual device, we chose the plan out the circuits, the sensors and the Arduino Code.
Here are the results from the third phase:
Sensors:
Lilypad
TMP36
,TO-226_straightlead.jpg)
Circuitry:
Arduino Code:
Future Goals:
- Prototyping the actual device
- Statistical Testing
- To reach prototyping phase, we need to finalize circuit design and sensors used
- Wheatstone Bridge/ General Circuit
- Lilypad vs. TMP36
- Statistical Testing
- Compare our device to known, accurate temperature sensing devices
- Use a One-way ANOVA Test to determine if our device is accurate