This week is about planning my final project proposal answering these questions:
What will it do?
A desktop device (lamp) to be placed on the office desk to monitor stress levels in the office environment.
This will work by reading biological signs of stress (like heart rate, respiration, transpiration, ocular movement, etc.,) of an employee and display it in color code (ex.: blue for relaxed gradually turning red if stressed); allowing them to be conscious about increasing stress levels during the day and the need for taking a short break or as a reminder of taking an active break. ;)
The device will also help manage or reduce stress by making the office worker engage in respiration exercises through pulsating movements (inflate and deflate) to synchronize with the user state by guiding the breathing.
Who has done what beforehand?
On the technical aspect, the stress measurement using a pulse sensor is widely used in smartwatches and other health devices that incorporated this feature and measurements by health monitoring apps.
Some examples from FabAcademy projects:
Some other investigation/projects:
What will you design?
The device is in itself a tangible user interface (TAU), I’ll be designing the shape of the device consisting of a 3 piece body (base, middle, and tip) with different functions and its assembly, the electronic board to control the sensors, communication, actuators and display the information, and the mechanism for the pulsating movement including a flexible outer skin.
What materials and components will be used?
Materials:
Base: MDF or fancy solid wood as it needs to be heavier for the rolly-polly effect. another option is 3D printing the base and using it as a mold for casting. This piece will be also the housing for the electronics components.
Middle: This is the part that will have the pulsating effect, this flexible skin could be 3D print (auxetic pattern), laser-cut pattern in cardboard, or casted silicone.
Tip: Cast clear resin. (3D printed mold).
Internal Mechanism: 3D print and laser cut MDF or acrylic.
Connection pieces: Fit between parts by 3D print.
Components:
- ATMega328P
- Pulse-oximeter sensor
- Lithium battery
- USB connector
- Wifi module
- Neopixel ring and other LEDs
- DC motor with reduction gear (the yellow one) or linear actuator
Where will they come from?
The materials and components from the FabLab Lima inventory and personal purchase. Some components would be purchased from online retailers like Sparkfun or Adafruit.
How much will they cost?
Around $100? BOM will be updated with final materials and components!
What parts and systems will be made?
The device is based on three modules:
Base: This piece will be the housing for the electronics components and the main support for the structure and mechanism.
Middle: This is the part that will have the pulsating effect, on the outside the flexible skin (need to be designed) will stretch and allow the light through and on the inside will house a pneumatic part (probably a ballon to be compressed and that doubles as a light diffuser for the LED ring) and the internal mechanic and motor for the pulsating movement.
Tip: On top of the device this part will house a LED that indicates actions on color code or blinking.
Internal Mechanism will allow the pulsating movement inside the device by compressing a pneumatic part and expanding the flexible skin.
Connection pieces: Fit between parts by 3D print.
What processes will be used?
- CNC machining
- 3D printing
- Laser cutting
- Molding and casting
- Design, milling, and soldering of the electronic board
- Vinyl cutting
What questions need to be answered?
Will it look and feel good? More than aesthetic pleasure a tangible interface need to be easily grabbed and feel good to the touch, the light signals need to be clear and intuitive. As having many parts and different fabrication techniques the final device may look a bit Frankenstein-ish.
Will the components fit? The egg shape of the device gives some space constraints for the electronics components and the mechanism that needs to fit inside the base pocket.
Will it balance correctly? The device should tumble like a rolly-polly, so the balance of the weight is crucial. This would be made by making the base heavier, but at the same time with enough space for housing the components, so the size of the pocket carved in the base should be considerer carefully (testing needed). Also, the mechanism and the internal structure that will support the tip should be light enough to keep the device balanced.
Will the mechanism be stable enough or have enough compression to make the pulsating movement? What about the gear ratio to mimic the respiration cycle? As mentioned before space and weight needs to be carefully considered, to achieve a smooth movement the type and control of the motor (PWM?), gear ratios, and timing need to be considered.
Will the readings and communication be accurate? To have consistent measurements we have to test the sensor and programming. Or how to choose the right microcontroller.
Will it be noisy? As a device to be used in calming exercises, the noise level needs to be minimum
How will it be evaluated?
If all of the above works, and following this Spiral Development guide:
First Spiral: Make the first prototype to test the fitting of the modules and test the fitting of electronic components
Second Spiral: Design and fabrication of the pulsating movement and the integration with the prototype.
Third Spiral: Programing and integration of the application with user testing!