The goal of this project is to develop a system of sensors that can detect and read the amount of force placed on it, each sensor will have a reading for the left and right foot respectively. We plan to do this by using force sensitive resistors to take in data that is sent to arduino, this data will be used to calculate an imbalance (calculation will take place in arduino) in the forces on each sensor, and display this imbalance for the user, we will develop an algorithm as well which will display whether this imbalance is undesirable or okay. In its final state, the project will be able to find imbalances in forces from pushing with the legs when standing or squatting. Applications for FootFrame are found in weightlifting and physical therapy, among other places.
- Jessie Korovin
- Adam Messer
- Isabel Shapiro
- Will Luer (TA)
- Detect the amount of force applied by feet on force sensitive resistors, up to 110 pounds per foot
- Be able to deliver a reading of the force from each resistor into arduino, and code a program that calculates and displays the difference between the force sensitive resistors in arduino
- Designing a foot stand that allows us to accurately and completely transmit all the force generated by feet onto the force sensitive resistors. Eight force sensors will be used to develop data (this number was chosen to support a Wheatstone bridge circuit)
- Developing an interface to show the information collected (difference in force readings between feet in LBS)
- Calibrating force resistors so they do not give inaccurate readings (can sometimes differ by 10%)
- Designing a program to deliver the reading using arduino
- Making sure the foot stands are stable and do not break, to make sure the user remains safe
- Making sure all the force is delivered onto the sensor
- Filtering data to get accurate results
- Ensuring the material that the sensor is housed in will not impact the quality of the data
- 2 SparkFun Load Cell Amplifier - HX711 [$9.95 each] https://www.sparkfun.com/products/13879?_ga=1.121117709.48925135.1486004091
- 2 SparkFun Load Sensor Combinator [$1.95 each] https://www.sparkfun.com/products/13878?_ga=1.52354092.48925135.1486004091
- 8 Load Sensors - 50 kg [$9.95 each] https://www.sparkfun.com/products/10245?_ga=1.9476016.48925135.1486004091
- 9V Battery Clip - [$4.29] https://www.amazon.com/Parts-Express-9V-Battery-Clip/dp/B0002ZPFU8
- 4 pack of 9V D batteries [$8.79] https://www.amazon.com/Duracell-MN-1604-Pack-MN1604/dp/B0164F986Q/ref=sr_1_3_a_it?ie=UTF8&qid=1486762819&sr=8-3&keywords=9v%2Bbattery&th=1
- 2 1 in x 15 in x 15 in wooden plates [$12.57 each] http://www.homedepot.com/p/1-in-x-15-in-x-1-25-ft-Pine-Edge-Glued-Panel-Round-Board-ZPRLR0115/205482872
- Arduino (supplied by lab) [$0.00]
- Personal Computer - for display screen and power source - (supplied by group) [$0.00]
- 3D printed load sensor connects[$0.00]
- Wooden platforms and blocks from machine shop [$0.00]
Code to be implemented and modified
The main ideas and their corresponding CAD diagrams are drawn out below. The overarching design is for two of the assemblies shown below to exist - one for each foot.
(above) An isometric view of the assembly minus the foot plate, featuring four load sensor support blocks and one centered nail guide - the foot plate will rest evenly upon each of the four load sensors. The nail guide is heightened millimeters lower than the tips of the load sensors. This way, the nail guide will not provide any upward force that could detract from the accurate data. However, a nail will be driven into the center of the top plate and through the nail guide. The nail guide will be attached to the base plate. This setup will prevent the nail or nail guide from providing an upward force on the foot plate, but will limit horizontal movement that could dislodge the foot plate from the top of the load sensors. This will also work to keep weight balanced across the sensors evenly.
(above) This view is a close up of the load sensor support block and a depiction of the load sensor itself, resting atop the support. The holes on top are for bolts or nails that will be used to hold the piece in place. The rectangular cut-out in the middle-front of the sensor support block is present so that when the load sensor receives a downward force, it can bend properly and calculate weight. Without the cutout, the T-shaped piece of the sensor could not drop below the top of the support block and would not accurately read the data.