# Title Team Members TA Documents Sponsor
61 Stick On Car Proximity Sensor
Aryan Damani
Raunak Bathwal
Shrijan Sathish
Angquan Yu final_paper1.pdf
Team Members:
Shrijan Sathish (shrijan2)
Aryan Damani (aryansd2)
Raunak Bathwal (raunakb2)

# Problem

Describe the problem you want to solve and motivate the need.

Many older cars lack proximity sensors that let the user know how close their car is to various obstacles, whether it be their garages, parking spot walls, or even curbs. Though this can be handled through various tricks of knowing where to look in the rearview or side mirrors to know where the front, sides, or back of the car is with respect to walls and other obstacles, it is always better to be sure. We aim to solve this inconvenience that comes with older model cars.

# Solution

Describe your design at a high-level, how it solves the problem, and introduce the subsystems of your project.

Our solution involves using 4 proximity sensors that can be placed on each corner of the car, with a receiver that can be placed inside the car. These will be linked through bluetooth and the receiver itself will also contain 4 lights on each of its corners. This will correspond with each sensor placed, and light up as well as produce an auditory cue (most likely small “beeps”) to alert the user how close they are to an obstacle and where it is. The closer you are to an obstacle, the faster the frequency of the beeps.

# Solution Components

## Subsystem 1: Proximity Sensor
The first, and main system, will be the sensors placed all around the car. Each module will be the same, regardless of where on the car it is placed. Each module will consist of 1-3 ultrasonic sensors(HC-SR04) based on their predicted placement on the vehicle, our custom PCB, a small watch battery, and a wireless RF transceiver (WRL-10534). The module will constantly transmit distance data to the receiver module located within the vehicle to make sure the driver is aware of how close they may be to any potential obstacles.

## Subsystem 2: Receiver

The receiver subsystem will be located within the vehicle, consisting of an RF receiver (WRL-10534) to communicate with the above proximity sensors, a power adapter to get power from the USB/car power, and a microcontroller(ATmega328P) to read input from proximity sensors, and output signals to control the lights and speakers over bluetooth using a bluetooth module (CC2541F256TRHATQ1) if necessary and if the vehicle is too close to an object.

## Subsystem 3: Lights + Speaker
The light and speaker system will consist of a small speaker that we have that will change frequency based on how close an object is, combined with a set of red LED diodes to represent which sensor is being triggered so the driver knows which direction to avoid.

# Criterion For Success

Our criterion for success will be testing with an actual car, where we reach a constant beep when we reach a distance of less than one foot to an obstacle, which will be our reassurance that the sensors work. Our second criterion for success is to get someone to use the system and determine if they are able to stop before/avoid obstacles with a relatively safe margin of error.

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.