Manav Arora, Hannah Carney, Brandon Sia, Luke Snyder, Dominic Spatola

This project was developed as part of the University of Pittsburgh Swanson School of Engineering course ENGR 0716 The Art of Making: An Introduction to Hands-on System Design and Engineering.

My Movie.mp4

Squat Sense is a wearable device that assesses your weight distribution while squatting. When squatting, there should be weight on the heel, base of the big toe, and base of the little toe. Failure to correctly distribute weight can result in injury.

Whether you are a squat pro or a beginner, Squat Sense gives you the confidence that your weight is correctly distributed.

On the diagram to the left, there are 3 points marked out on the feet. These three points are known as the tripod and are there most common points of reference for measuring pressure.

Squat Sense uses three sensors, one at each point of contact to detect pressure across the feet. Each sensor has a corresponding neo-pixel and a buzzer to alert you exactly where the problem lies. It is designed to be easily worn and implemented into your work-out routine. It has a battery length of between 7-286 hours ensuring it will last for at least one workout (or hundreds) before being recharged.

How to Use

Put on Squat Sense

Connect Battery

Toggle Switch

Materials

Circuit Bluefruit Playground

Microcontroller that controls all inputs and outputs

Velostat

Variable resistor that decreases in resistance with increasing pressure

Neopixels x3

Lights up to when there is no pressure on corresponding sensor

Buzzer

Provides auditory feedback to alert the user to the problem

Switch

Allows the buzzer to be turned off

Lipo battery

Powers the microcontroller

Construction & Connections

Solder

Thread
Scotch tape
Silicon Wire

Functional Diagram

There is a pressure threshold for the velostat pads.
If there is not enough pressure on the velostat pads, the corresponding neopixel will begin to flash.
If the buzzer is turned on, the buzzer will activate. The buzzer activates with any neo-pixel.

This loop is constantly running as soon as there is power.

System Diagrams

Velostat Pads

We used velostat to make the pressure sensors. Velostat is a fabric-like substance that acts as a variable resistor due to pressure changes. Increasing the pressure decreases the resistance of the material. Each piece has to be calibrated then the pressure can be measured.

The conducting ends of the wire are attached to opposite sides of the velostat so it can function as a resistor. We used foil to increase surface area. Masking tape held the foil-velostat apparatus together and the wires were attached to the foil with copper tape.

Structural Connections

The shoe itself is covered with a stocking so it could potentially be transferred to a different shoe. The bulk of the circuitry and components lie on the top of the shoe while the velostat pads are on the bottom. Each component is connected to the stocking using tape or is sewed in place. Silcon wires are soldered in place and connect the components.

Wiring

Velostat Pads

Each velostat pad must be connected to power, ground, and an analog pin. While they needed individual input pins, they were able to share ground and power pins. The resistor connected to ground is known as a pull-up/pull-down resistor. It is responsible for equalizing the voltage.

Buzzer, Switch, and Battery

The battery is simply connected to the power port of the bluefruit. The switch and buzzer are connected in series so the switch controls the buzzer. They are connected to the audio pin (which provides power) as well as to ground.

Neopixel

The neopixels are conenected in series. Each is connected to ground and power as well as to the neighboring neopixels or an analog pin.

Future Improvements

Louder buzzer with option to connect with bluetooth headphones
More secure attatchment of components particularly the lipo battery
Easier to take Squat Sense off a shoe or put it on
Less conspicuous
Less wiring
Ability to use with or without a shoe, just using the stocking

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