Project

# Title Team Members TA Documents Sponsor
64 # Secure Food delivery dropbox
 Dhruva Dammanna
Rohan Samudrala
Taniah Napier
 Chi Zhang proposal1.pdf
# Secure Food delivery Dropbox

Team Members:
- Rohan Samudrala (rohans11)
- Dhruva Dammanna (dhruvad2)
- Taniah Napier (tnapier2)

# Problem
70% of college students order food from a third-party delivery service like uber eats or doordash weekly. Unfortunately, many food deliveries can get stolen as some people order ahead of time when ordering at the door dash and the food will just stay in front of their house for anyone to take. We want to prevent people from stealing food deliveries.

# Solution
Our solution is to create an insulated box that only the delivery person and customer can open, locking the food in otherwise. The box will generate a one time use passcode that the customer can send to the driver through the app. Once the driver drops off the food, a weight sensor will ensure the delivery was actually left and lock the box. The weight sensor also ensures that the driver can not go back and take the food. After, the orderer uses a master passcode to open the box and receive their order.


# Solution Components

## Subsystem 1: 9 digit keypad
This is used for the driver to put in the code to unlock the box. The code for the driver is a one time use, so it will change after the food is placed inside. The user has a master code that always works so they can unlock. The code put into the keypad will be checked if it is correct and then unlock the box.

Parts used: ADAFRUIT 1824(Keypad)


## Subsystem 2: Weight sensor
The weight sensor is used to check if food is in the box. It is also used to generate a new passcode for the keypad for the next driver. The old pass code that the previous driver used will not work after the weight sensor is activated.

Parts used: TAL220B-3KG(Weight sensor)


## Subsystem 3: Locking mechanism
When the box is closed a servo motor will push a deadbolt, locking the box shut.

Parts used: 900-00005 (servo)


## Subsystem 4: Control and Power System
We will use a microcontroller to write code in C++ or C to interact with the sensors and the rest of the project. A random passcode will be generated here for the driver to use. Once generated, the wifi capability of the ESP32 will send it to the user. Also the voltage will be regulated here. It is battery powered.

Parts used: ESP32-WROOM-32 (Microcontroller), AP2112K-3.3(Battery), 1N4148 diode (Voltage Regulation)

## Subsystem 5: Box Insulation
We will use foam panels to insulate the food inside so that it stays at the temperature that it needs to stay at. This will make the food more enjoyable.

Part: Foam Panels


# Criterion For Success
Food containment unit is initially locked. Once specified 4 digit codes are inputted into the keypad of the containment unit, the containment unit will unlock.
A 4 digit code is randomly generated upon weight sensor activation. This randomly generated code is intended for 1 time use.
Once the weight sensor detects that the food has been placed inside the containment unit, the unit will lock.
Once the weight sensor detects that the food has been placed inside the containment unit, the randomly generated passcode will no longer work and another code will be generated for next use.
A specific 4 master code can be entered at any time to the keypad and the food containment unit will open.
Both the random code and the master code will be sent to the user.

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.