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# Title Team Members TA Documents Sponsor
52 Posture & Neck Strain Monitor for Long Study Sessions
 Heet Chauhan
Hrishikesh Deshpande
Praveen Madan
 Xiyue Zhu design_document1.pdf
proposal1.pdf
# Posture & Neck Strain Monitor for Long Study Sessions

Team Members:
- Hrishikesh Deshpande (hd11)
- Praveen Madan (madan7)
- Heet Chauhan (heetc2)

# Problem

Long study or work sessions at a desk make it easy to slip into bad posture without noticing until neck or back pain has already set in. Existing solutions are poorly suited to everyday use - desk mounted cameras are expensive and raise privacy concerns, back braces are bulky and uncomfortable for long wear, and app based posture trackers usually require a subscription and constant phone interaction. Single-sensor clip-on posture devices have also historically been unreliable, since one IMU alone cannot distinguish real slouching from ordinary head movement (like glancing down at a book). We need a small, low cost, standalone device that reliably monitors both posture and neck strain, and gives a quick nudge when the wearer starts slouching, without requiring a phone or subscription to be useful.

# Solution

We propose a small two-IMU wearable system: one IMU mounted on the glasses (tracking head orientation) and one mounted on the collar/shirt (tracking torso orientation). By comparing the two, the device can compute the actual relative angle between head and torso — a true measure of neck strain and slouching — rather than relying on either sensor alone, which past single-IMU posture devices have struggled with. The glasses-mounted sensor board connects to the main collar-mounted board via a thin wire.

During setup, the user calibrates a "neutral" posture baseline while seated normally, and the device monitors deviation of the relative head-to-torso angle from that baseline in real time. If the wearer holds a slouched or strained position past a configurable threshold, the device alerts them via a vibration motor, prompting them to correct their posture.

The system is built around three core subsystems: sensing (dual IMU-based relative orientation tracking), processing/control (an STM32 MCU running sensor fusion and threshold logic across both IMUs), and feedback/power (vibration motor, LED, button interface, and battery management). An extra goal could be adding a wireless subsystem (BLE) to log posture data over time to a companion phone app.

# Solution Components

## Sensing Subsystem

Captures raw motion data from two locations - head and torso - which the processing subsystem fuses into a relative head-to-torso angle estimate. This relative angle is what actually indicates neck strain and slouching, rather than either sensor's absolute orientation alone.
- IMU x2: ICM-42670-P (TDK InvenSense, 6-axis accel + gyro, I2C, AD0 pin used to assign distinct addresses for both sensors on one bus)
- Small sensor sub-board for the glasses-mounted IMU, connected to the main board via thin wire

## Processing & Control Subsystem

Runs sensor fusion on both IMUs' data, computes the relative angle between head and torso orientation, compares that relative angle against the calibrated baseline, tracks how long the wearer has been out of range, and triggers alerts when the threshold is exceeded. Also manages the calibration/mute button input.
- MCU: STM32L452RE (STM32L4 series, low-power Cortex-M4)
- Tactile push button for calibration/mute

## Feedback Subsystem

Alerts the wearer when sustained bad posture or neck strain is detected, with both a discreet (vibration) and noticeable (LED) option.
- Vibration motor: Precision Microdrives 306-100
- Status LED (0603 SMD), driven via MOSFET (DMG2305UX)

## Power Subsystem

Powers the device for a full day of use in a compact, lightweight form factor and handles battery charging.
- Battery: 3.7V LiPo, ~150mAh
- Charge IC: MCP73831 (single-cell LiPo linear charger)
- Regulator to provide a clean 3.3V rail to MCU and both IMUs

## Wireless Subsystem (Extra Goal)

Allows posture and neck strain data to be logged over time and viewed as trends on a companion app, rather than only reacting to current posture.
- BLE module: STM32WB55CG or nRF52832 as a discrete BLE co-processor

# Criterion For Success

- The device detects a sustained relative head-to-torso angle change of at least 15° from the calibrated baseline, held for 10 seconds, and triggers an alert within 1 second, which should be verified with >90% detection rate over 20 trials, including trials with independent head or torso movement alone (e.g., glancing down while seated upright, or shifting torso without tilting the head) that should not trigger a false alert.
- The calibration button correctly resets the baseline relative angle, verified by no false alerts for at least 5 minutes after calibration while the wearer stays upright and still.
- The device runs continuously on a single charge for at least 8 hours of active monitoring, verified via bench testing.
- The fully assembled device (both IMU boards, main PCB, battery, vibration motor, enclosures) weighs no more than 25g total, verified by direct measurement, so that its weight does not shift sensor position or affect calibration during normal wear.
- The main PCB fits within a 4cm x 3cm x 1.5cm enclosure, and the glasses-mounted sensor sub-board fits within a 1.5cm x 1cm x 0.5cm enclosure, both measured on the assembled boards.
- The alert is reliably noticed by the wearer, verified by at least 8/10 test users noticing it within 3 seconds of triggering.
- (Extra Goal) BLE logging has less than 5% data loss over a 30-minute continuous session.

Tesla Coil Guitar Amp

David Mengel, Griffin Rzonca

Featured Project

# Tesla Coil Guitar Amp

Team Members:

* Griffin Rzonca (grzonca2)

* David Mengel (dmengel3)

# Problem:

Musicians are known for their affinity for flashy and creative displays and playing styles, especially during their live performances. One of the best ways to foster this creativity and allow artists to express themselves is a new type of amp that is both visually stunning and sonically interesting.

# Solution:

We propose a guitar amp that uses a Tesla coil to create a unique tone and dazzling visuals to go along with it. The amp will take the input from an electric guitar and use this to change the frequency of a tesla coil's sparks onto a grounding rod, creating a tone that matches that of the guitar.

# Solution Components:

## Audio Input and Frequency Processing -

This will convert the output of the guitar into a square wave to be fed as a driver for the tesla coil. This can be done using a network of op-amps. We will also use an LED and phototransistor to separate the user from the rest of the circuit, so that they have no direct connection to any high voltage circuitry. In order to operate our tesla coil, we need to drive it at its resonant frequency. Initial calculations and research have this value somewhere around 100kHz. The ESP32 microcontroller can create up to 40MHz, so we will use this to drive our circuit. In order to output different notes, we will use pulses of the resonant frequency, with the pulses at the frequency of the desired note.

## Solid-state switching -

We will use semiconductor switching rather than the comparably popular air-gap switching, as this poses less of a safety issue and is more reliable and modifiable. We will use a microcontroller, an ESP 32, to control an IR2110 gate driver IC and two to four IGBTs held high or low in order to complete the circuit as the coil triggers, acting in place of the air gap switch. These can all be included on our PCB.

## Power Supply -

We will use a 120V AC input to power the tesla coil and most likely a neon sign transformer if needed to step up the voltage to power our coil.

## Tesla Coil -

Consists of a few wire loops on the primary side and a 100-turn coil of copper wire in order to step up voltage for spark generation. Will also require a toroidal loop of PVC wrapped in aluminum foil in order to properly shape the electric field for optimal arcing. These pieces can be modular for easy storage and transport.

## Grounding rod -

All sparks will be directed onto a grounded metal rod 3-5cm from the coil. The rest of the circuit will use a separate neutral to further protect against damage. If underground cable concerns exist, we can call an Ameren inspector when we test the coil to mark any buried cables to ensure our grounding rod is placed in a safe location.

## Safety -

Tesla coils have been built for senior design in the past, and as noted by TAs, there are several safety precautions needed for this project to work. We reviewed guidelines from dozens of recorded tesla coil builds and determined the following precautions:

* The tesla coil will never be turned on indoors, it will be tested outside with multiple group members present using an outdoor wall outlet, with cones to create a circle of safety to keep bystanders away.

* We will keep everyone at least 10ft away while the coil is active.

* The voltage can reach up to 100kV (albeit low current) so all sparks will be directed onto a grounding rod 3-5cm away, as a general rule of thumb is each 30kV can bridge a 1cm gap.

* The power supply (120-240V) components will be built and tested in the power electronics lab.

* The coil will have an emergency stop button and a fuse at the power supply.

* The cable from the guitar will use a phototransistor so that the user is not connected to a circuit with any power electronics.

# Criterion for Success:

To consider this project successful, we would like to see:

* No safety violations or injuries.

* A tesla coil that produces small visible and audible 3-5cm sparks to our ground rod.

* The coil can play several different notes and tones.

* The coil can take input from the guitar and will play the corresponding notes.

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