Prototyping
Sketch Models
During the design process, there were many sketch models made to test concepts and improve the design. The earlier models were made from thin sheets of EVA foam that were cut and layered to create a 3D model.
There were also several paper models made to held determine sizing and sensor placement. Each of these models helped to further the design process and effected the final product.
Electronics
The main components for the electronic consist of three Force Sensitive Resistors (FSR) that are placed at the front, side and back of the foot. These FSR’s output a value depending on the amount of force placed upon them. These values are then sent to the microprocessor.
The microprocessor then uses the Bluetooth chip to send these values to the app. The app uses these values to determine whether the runner is using the correct form and technique.
By looking at what sensor activates first as the user is running, we can determine what part of the foot hits the ground first. If the user is running in the correct barefoot running form, the sensors at the front and the side should activate first. However, if the user is running incorrectly, the back sensor will activate first.
Once the app has determined what part of the user’s form needs to be improved, it can then suggest drills and exercises to correct this form.
The product is charged using piezoelectric charging. The piezoelectric elements consist of two metal plates separated by lead zirconate titanate crystals. When these elements are compressed, energy is produced and sent to the battery.
The FSR and piezoelectric charging have two separate circuits. However, to save space, the components from both circuits have been placed on the same circuit.
The electronics for this prototype were run off of an Arduino. This was a quick way to set up a working prototype, however, it was bigger than the final product electronics would be. As the electronics will not fit into the insole, they will need to be held externally.
To hold the electronics, a small box was 3D printed that would clip onto a shoe. As this box will be used to conduct the first round of user testing, having a visually appealing model would help with online promotion. The logo was printed onto the lid of the box and was filled in with transparent filament. Then, several LED’s were placed into the box and set to pulse when the device was on.
This not only serves to make the box more visually appealing, but it shows when the device is on and sending readings out.
