Project

# Title Team Members TA Documents Sponsor
68 Insole Pressure Sensing System for Running
 Aarush Sivanesan
Joseph Casino
Matthew Weng
 Xiaodong Ye design_document1.pdf
proposal1.pdf
Members:
Joseph Casino (jcasino2)
Aarush Sivanesan (aarush2)
Matthew Weng (mw87)

# Problem
Runners often develop injuries or inefficient running form due to high impact forces, poor foot-strike mechanics (heel vs midfoot), asymmetrical loading, or inconsistent cadence. Most runners do not have an easy way to measure how their foot actually loads the ground over time, since gait labs and force-sensing soles are expensive and geared towards physical therapy, research, or professional athletics. Existing consumer wearables estimate cadence using wrist/hip motion, but do not directly measure foot-ground pressure/impact. There is a need for a low-profile, shoe-integrated system that can quantify foot impact and pressure distribution during real runs while remaining comfortable, lightweight, and accessible to everyday runners.

# Solution
We propose a thin-film pressure sensor insole system for running shoes that measures the force applied by the foot to the ground throughout each stride. A flexible sensor array embedded on top of the shoe foam (or placed under the insole) will capture pressure through the foot’s main contact points (forefoot, heel, and midfoot). A small electronics module will attach to the shoe heel or tongue and contain MCU, battery, and Bluetooth modules. The MCU will sample the pressure sensors, detect foot-strike events, and compute basic metrics such as step count, cadence, contact time, and estimated distance (using cadence/stride-length calibration and optional IMU/GPS data). Data will be streamed over Bluetooth Low Energy (BLE) to a phone for visualization, logging, and further analysis.

# Solution Components

**Subsystem 1: Thin-Film Pressure Sensor Insole Array**

This subsystem senses foot pressure at key regions of the shoe to capture impact patterns and pressure distribution during stance. The sensor insole would fit either on top or bottom of the foam insole of the shoe.

Components:
- Thin-film force sensors (multiple locations): Interlink Electronics FSR 402
- Flexible interconnect/cabling: FFC/FPC cable (0.5 mm pitch) (generic)
- Connector (board-side): Molex 503480-0490 (4-pos FFC/FPC connector) (size can be adjusted based on channel count)

**Subsystem 2: Analog Front-End + ADC Data Acquisition**

This subsystem converts each sensor data to data that can be read to the MCU. To sample all the sensors on the foot, we sample between all the sensors with a MUX. We then properly filter and amplify the data from the sensor through the op-amp. This data then gets digitized through an ADC.

Components:
- 16-bit ADC: MCP3425A0T-E/CH
- Analog multiplexer: CD74HC4067SM96
- Op-amp: TLV9062IDR

**Subsystem 3: Microcontroller + BLE Wireless Telemetry**

This subsystem houses our MCU which will control sampling,collect data, timestamp data, and transmit results via BLE.

Components:
- MCU module: ESP32-C3-WROOM-02
- Programming/debug interface: Tag-Connect TC2030-IDC

**Subsystem 4: Optional Motion Sensing (IMU)**

This extra subsystem provides accelerometer/gyro data to gather speed data, estimate and improve stride data and length, and improve cadence robustness when the pressure signals are noisy.

Components:
- 6-axis IMU: ST LSM6DSOXTR or equivalent

**Subsystem 5: Power Management + Charging**

This subsystem powers the in-shoe electronics safely and supports rechargeable operation if applicable. The design regulates battery voltage to stable rails for the MCU and sensors. We have a wide range of batteries that we would like to work with initially to weigh out the pros and cons of each.

Components:

Battery options:
- 3.7V Li-Po (300–500 mAh)
- 3V Coin Battery
- AAA Alkaline Battery
- BMS IC for Li-Po : MCP73831T-2ACI/OT
- 3.3V regulator : MCP1700T-3302E/TT

**Subsystem 6: Phone Interface / Data Visualization**

This subsystem provides the wireless interface between the device and a smartphone or website which displays metrics to the runner and logs sessions. Initial versions can use a simple BLE GATT service viewed in a standard BLE app; a custom website or phone UI can be added if time permits.

Components:
- BLE GATT profile (firmware-defined)
- Prototype viewer: nRF Connect app or alternative

# Criterion For Success

Efficiency: The system shall sample plantar pressure sensor data at a minimum rate of 100 Hz and transmit the data over Bluetooth Low Energy with no more than 5% packet loss during continuous operation.

Accuracy: The system shall detect foot-strike events and report running cadence with an accuracy of ±3 BPM compared to a stopwatch or smartwatch reference over a controlled running trial.

Continuity/Longevity: The device shall operate continuously for at least 1 hour on battery power while performing active sensing and BLE data streaming.

Illini Voyager

Cameron Jones, Christopher Xu

Featured Project

# Illini Voyager

Team Members:

- Christopher Xu (cyx3)

- Cameron Jones (ccj4)

# Problem

Weather balloons are commonly used to collect meteorological data, such as temperature, pressure, humidity, and wind velocity at different layers of the atmosphere. These data are key components of today’s best predictive weather models, and we rely on the constant launch of radiosondes to meet this need. Most weather balloons cannot control their altitude and direction of travel, but if they could, we would be able to collect data from specific regions of the atmosphere, avoid commercial airspaces, increase range and duration of flights by optimizing position relative to weather forecasts, and avoid pollution from constant launches. A long endurance balloon platform also uniquely enables the performance of interesting payloads, such as the detection of high energy particles over the Antarctic, in situ measurements of high-altitude weather phenomena in remote locations, and radiation testing of electronic components. Since nearly all weather balloons flown today lack the control capability to make this possible, we are presented with an interesting engineering challenge with a significant payoff.

# Solution

We aim to solve this problem through the use of an automated venting and ballast system, which can modulate the balloon’s buoyancy to achieve a target altitude. Given accurate GPS positioning and modeling of the jetstream, we can fly at certain altitudes to navigate the winds of the upper atmosphere. The venting will be performed by an actuator fixed to the neck of the balloon, and the ballast drops will consist of small, biodegradable BBs, which pose no threat to anything below the balloon. Similar existing solutions, particularly the Stanford Valbal project, have had significant success with their long endurance launches. We are seeking to improve upon their endurance by increasing longevity from a power consumption and recharging standpoint, implementing a more capable altitude control algorithm which minimizes helium and ballast expenditures, and optimizing mechanisms to increase ballast capacity. With altitude control, the balloon has access to winds going in different directions at different layers in the atmosphere, making it possible to roughly adjust its horizontal trajectory and collect data from multiple regions in one flight.

# Solution Components

## Vent Valve and Cut-down (Mechanical)

A servo actuates a valve that allows helium to exit the balloon, decreasing the lift. The valve must allow enough flow when open to slow the initial ascent of the balloon at the cruising altitude, yet create a tight seal when closed. The same servo will also be able to detach or cut down the balloon in case we need to end the flight early. A parachute will deploy under free fall.

## Ballast Dropper (Mechanical)

A small DC motor spins a wheel to drop [biodegradable BBs](https://www.amazon.com/Force-Premium-Biodegradable-Airsoft-Ammo-20/dp/B08SHJ7LWC/). As the total weight of the system decreases, the balloon will gain altitude. This mechanism must drop BBs at a consistent weight and operate for long durations without jamming or have a method of detecting the jams and running an unjamming sequence.

## Power Subsystem (Electrical)

The entire system will be powered by a few lightweight rechargeable batteries (such as 18650). A battery protection system (such as BQ294x) will have an undervoltage and overvoltage cutoff to ensure safe voltages on the cells during charge and discharge.

## Control Subsystem (Electrical)

An STM32 microcontroller will serve as our flight computer and has the responsibility for commanding actuators, collecting data, and managing communications back to our ground console. We’ll likely use an internal watchdog timer to recover from system faults. On the same board, we’ll have GPS, pressure, temperature, and humidity sensors to determine how to actuate the vent valve or ballast.

## Communication Subsystem (Electrical)

The microcontroller will communicate via serial to the satellite modem (Iridium 9603N), sending small packets back to us on the ground with a minimum frequency of once per hour. There will also be a LED beacon visible up to 5 miles at night to meet regulations. We have read through the FAA part 101 regulations and believe our system meets all requirements to enable a safe, legal, and ethical balloon flight.

## Ground Subsystem (Software)

We will maintain a web server which will receive location reports and other data packets from our balloon while it is in flight. This piece of software will also allow us to schedule commands, respond to error conditions, and adjust the control algorithm while in flight.

# Criterion For Success

We aim to launch the balloon a week before the demo date. At the demo, we will present any data collected from the launch, as well as an identical version of the avionics board showing its functionality. A quantitative goal for the balloon is to survive 24 hours in the air, collect data for that whole period, and report it back via the satellite modem.

![Block diagram](https://i.imgur.com/0yazJTu.png)