Project

# Title Team Members TA Documents Sponsor
20 ZZZ-Mate : Pulse Driven White Noise Generator
 Haruya Kamitani
Sanjana Chunduri
Vakaris Ragauskas
 Jeff Chang design_document1.pdf
design_document2.pdf
final_paper1.pdf
presentation1.pdf
proposal1.pdf
video
Team Members: Sanjana Chunduri (sc65) / Vakaris Ragauskas (vragau2) / Haruya Kamitani (hkamit2)

#Problem:

According to the CDC, about 70 million Americans suffer from sleep deprivation. Lack of sleep causes various issues in our daily lives such as tiredness, lack of concentration, and in extreme cases, heart failure, diabetes, and various serious conditions.
Some of us rely on external sound sources for falling asleep. Currently, there are various white noise machines out in the market. However, most of these devices output a single, continuous signal. According to one article (https://krisp.ai/blog/background-noise-impact/), “the continuous background noise also known as white noise which comes from machines and other appliances, can harm your brain, it does so by overstimulating your auditory cortex”. According to one Healthline article (https://www.healthline.com/health/parenting/white-noise-for-babies#cons), a 2014 study concluded that “regular exposure to these sound pressure levels may be damaging to infant hearing and auditory development.”

#Solution:

White noise is typically beneficial during the earlier sleep stages, when people are more likely to be awoken by distracting noises or thoughts. However, rather than continuously playing background noise through the night and overstimulating the auditory cortex, our design aims to combat typical sleep deprivation issues by supporting users through all stages of their sleep cycle: Wake, light sleep, deep sleep, REM, and repeat. By taking pulse rate measurements as an indicator of the user’s current sleep stage, our sound generation device will adjust the volume of the white noise. A wristband with a photo sensor and green LEDs will be used to detect the user’s heart rate and will wirelessly relay the information to the white noise generator to adjust the volume as necessary.

#Solution Components

-Subsystem 1(Noise Source):

Power Supply Section: Noise source unit will be powered by 9-15VDC voltage. AC/DC adapter cable will be used. This power supply will provide a necessary power for MPU and if necessary, for speaker power amplifier as well as noise source.

MPU: ESP32 or related with built in Bluetooth/WiFi. This will be used to communicate with another ESP32 which will be built into the wearable band. The pulse rate data received from the wearable band will be used to control the output level of the noise source.

Speaker: Speaker with a wideband output frequency range (100Hz - 20kHz) will be used as white noise has an even power level across the full frequency spectrum. We may implement a power amplifier circuit with a simple transistor topology.

Noise Source: If it is manageable through ESP32, this will be programmed in MPU. Otherwise, transistor/opamp based white noise source will be implemented.

-Subsystem 2 (Wearable band):
MPU: another ESP32 microcontroller to send the pulse data to the main speaker/source unit.

Heart rate sensor: MAX30100 or MAX30102 or SEN11574

Battery: Lithium ion 3.3/5VDC



#Criterion For Success

One high-level goal of our project is to have wireless communication between a heart rate sensor wristband and a white noise machine. This wristband should be able to detect the heart rate of the user and differentiate between the four sleep stages of the user and differentiate between slight increases in heart rate to detect unrest. With software implementation, the WNG should decrease in volume when transitioning between sleep stages and after detecting an increase in heart rate.

Active Cell Balancing for Solar Vehicle Battery Pack

Tara D'Souza, John Han, Rohan Kamatar

Featured Project

# Problem

Illini Solar Car (ISC) utilizes lithium ion battery packs with 28 series modules of 15 parallel cells each. In order to ensure safe operation, each battery cell must remain in its safe voltage operating range (2.5 - 4.2 V). Currently, all modules charge and discharge simultaneously. If any single module reaches 4.2V while charging, or 2.5V while discharging, the car must stop charging or discharging, respectively. During normal use, it is natural for the modules to become unbalanced. As the pack grows more unbalanced, the capacity of the entire battery pack decreases as it can only charge and discharge to the range of the lowest capacity module. An actively balanced battery box would ensure that we utilize all possible charge during the race, up to 5% more charge based on previous calculations.

# Solution Overview

We will implement active balancing which will redistribute charge in order to fully utilize the capacity of every module. This system will be verified within a test battery box so that it can be incorporated into future solar vehicles.

Solution Components:

- Test Battery Box (Hardware): The test battery box provides an interface to test new battery management circuitry and active balancing.

- Battery Sensors (Hardware): The current battery sensors for ISC do not include hardware necessary for active balancing. The revised PCB will include the active balancing components proposed below while also including voltage and temperature sensing for each cell.

- Active Balancing Circuit (Hardware): The active balancing circuit includes a switching regulator IC, transformers, and the cell voltage monitors.

- BMS Test firmware (Software): The Battery Management System requires new firmware to control and test active balancing.

# Criterion for Success

- Charge can be redistributed from one module to another during discharge and charge, to be demonstrated by collected data of cell voltages over time.

- BMS can control balancing.

- The battery pack should always be kept within safe operating conditions.

- Test battery box provides a safe and usable platform for future tests.