Project

# Title Team Members TA Documents Sponsor
22 Lost Object Search Technology - Brittany, Cecil, and Adithya
 Adithya Sairam
Brittany Joy
Cecil Macgregor
 Daniel Gardner design_document0.pdf
final_paper0.pdf
presentation0.pdf
proposal0.pdf
bkjoy2, macgreg2, sairam2,

Brittany Joy, Cecil Macgregor, Adithya Sairam

We will create a lost object finder called Lost Object Search Technology or LOST, primarily targeted towards deaf and/or blind people. Using three different radio-frequency transmitters connected to a receiver unit, the user will play "Hot or Cold" to find the transmitters. There will be visual, audible, and tactile feedback using a LED, a speaker, and a vibration motor respectively. As the user gets closer to the transmitter, the three different stimuli will become stronger. The primary differences between this product and existing lost object finders are that LOST utilizes multiple senses to interact with the user, so impaired users can still detect using at least one of their senses. Additionally, LOST doesn’t require a paired app or cell phone and it will use radio-frequency waves around 800MHz and ensure that there is enough power for the transmitter signal to go through walls.

Portability and power are major factors, so once we have working prototypes of the RF transmitters and receiver, the final versions will use printed circuit boards. Expected maximum dimensions before the PCB are 3” x 1.5” x 0.5” for the transmitters and 4” x 2” x 0.5” for the hand-held receiver. The transmitter will have a master power switch so it will only drain power when turned on. The receivers will be constantly on using a 9-volt battery but we will aim towards having a low-power design using a coin battery for the transmitters. After PCB, the transmitters can be attached with adhesives to cell phones, wallets or small objects, and the receiver could be attached to a belt or a necklace on person. Therefore, we could create small, easy-to-use trackers for various objects, which can be utilized by the disabled or the scatterbrained to easily locate their belongings.

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.