Project

# Title Team Members TA Documents Sponsor
74 OMNIMOUSE - PIEZOELECTRIC SENSOR MOUSE
Area Award: Ergonomics
 Jie Jia
Yifei Li
Zhengfeng Wu
 Kexin Hui design_document0.pdf
final_paper0.pdf
presentation0.pdf
proposal0.pdf
This new interface device, the OmniMouse, is a dome shaped mouse that uses a band of piezoelectric sensors around the edge to sense directional input from the user. The user can simulate clicking actions through activating gestures from a central pressure sensor on the top of the dome. (For instance, scrolling up would have the user click the center and move their hand up, while a left click would be clicking the center and moving their hand to the left).

The device will be connected via bluetooth and utilize rechargeable li-ion batteries, with all electronic parts being housed within the dome chassis. We will be building the sensor array, power/recharge circuit, and custom PCB with shell/chassis parts built from the machine shop or 3d-printed. Sensor array would be connected to a microcontroller that processes the inputs from the different sensors, maps it into 2d space, and provides the mouse data to our mouse driver.

This new design adds a wide range of varied motion that can help ease stress on the users hands while providing a novel way to interact with a computer.

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.