Project

# Title Team Members TA Documents Sponsor
8 Secure Smart Locker for Doorstep Delivery
 Ernesto Marquez
Maxwell Armbruster
Samarth Jain
 William Zhang design_document1.pdf
final_paper1.pdf
other1.pdf
presentation1.pdf
proposal1.pdf
Team Members

In-Person: Max Armbruster (maa8), Samarth Jain (samarth3)
Online: Ernesto Marquez (ernesto2)

# Problem

The current global pandemic has moved many people's shopping habits online as e-tailing is much safer than retailing. The result is many more packages sitting idle on doorsteps, vulnerable to package thieves. I've personally had several packages stolen from my doorstep and it's quite frustrating as there isn't much that delivery service companies can do to help you. Your best bet is to order to something like an Amazon Locker or P.O. Box, but those add a layer of inconvenience to "home" delivery and are essentially just as COVID-risky as retail is.

# Solution Overview

Our solution is to design a secure smart locker to be placed on one's doorstep. Delivery drivers will scan a temporary QR code using a reader mounted to the locker, upon which the door will open. Once the package is placed inside and the door is closed, the locker will use the owner's WiFi to notify him/her of the delivery. Both the owner and the delivery person will interact with the locker using a mobile app that we develop.

# Solution Components

## Mechanical Design

Ideally, the locker should have a footprint that’s roughly 14”x16” and a height of at least a few feet, to accommodate most package sizes. Since having a prototype that fits these dimensions exactly is not critical to demonstrate our project’s function, we may deviate from these measurements. Namely, we might make it smaller to make transportation and storage of the prototype easier. Any appropriately sized container with a hinged door/lid should work for modification.

## Power

We plan to use a 12V DC power adapter that will plug into the wall jack on one’s porch or in one’s apartment lobby. The other end will feed through a small access hole in the locker and go straight to our PCB. From there we will have overvoltage, overcurrent, and reverse current protection, before breaking out into whatever other power we need (5V, 3.3V, etc.).

We’d also like to include a rechargeable battery solely for powering the alarm (detailed below) in the case that the power is disconnected by someone trying to steal the locker. This would be accessible inside of the locker for the owner to recharge/replace.

## Security

For the latching system on the door we can use some sort of cheap ~$10 solenoid lock. We would want one that is fail secure (door remains locked when power is disconnected). If we go too cheap, the lock could be damaged by someone trying to force the locker open, but I'd like to imagine that your average customer wouldn't have to worry about someone trying to forcibly access the locker more than once. We could always offer to repair the lock for free if it is damaged in this manner. After all, the point of a lock isn't to make something impossible to access, but rather inconvenient and attention-drawing.

To help in drawing attention, we plan to use a speaker on the locker to sound an alarm in the case that the locker is unplugged and stolen. This speaker will be powered by the rechargeable battery mentioned above. If the owner is planning on unplugging the locker themselves, the battery is accessible on the inside of the locker for them to unplug it and disable the alarm. When the locker is powered, this speaker will be used to beep softly while the door is open, to remind delivery people to close it before they leave.

Finally, we will mount a camera to the front/top of the locker which will take a picture whenever the locker is opened. This picture will be included in the notification sent to the owner. A live feed from this camera can be accessed from the mobile app.

## Mobile App

We will design a mobile app to be used by the owner of the smart locker to receive delivery notifications, unlock the device remotely, and access a live feed of the security camera. For the purpose of this prototype, this app will also be used by the delivery person to display the QR code for unlocking the device.

# Criterion for Success

We would consider our project a success if it achieves:

- Secure locking mechanism that makes it inconvenient for a thief to access the locker interior, to the point where they would rather move on to the next house
- Mobile app that allows the owner and delivery person to interact with the locker
- Speaker that doubles as an alarm when the locker is unplugged

The camera would be nice but the locker could function without it, in case we run short on time. If we instead have extra time, we can direct our attention to fleshing out the mobile app, maybe allowing the owner to speak through the speaker on the locker, to talk to a delivery person who needs instruction, or to taunt would-be thieves.

## COVID Shutdown Contingency Plan

In case we end up going online, I plan to make a simple version of the locker in my garage, such that it doesn’t require a PCB. I could probably use a breadboard and just ditch the camera. Our other group members can then work on the mobile app, and we can pretend like the app is able to communicate with the locker.

Tesla Coil Guitar Amp

David Mengel, Griffin Rzonca

Featured Project

# Tesla Coil Guitar Amp

Team Members:

* Griffin Rzonca (grzonca2)

* David Mengel (dmengel3)

# Problem:

Musicians are known for their affinity for flashy and creative displays and playing styles, especially during their live performances. One of the best ways to foster this creativity and allow artists to express themselves is a new type of amp that is both visually stunning and sonically interesting.

# Solution:

We propose a guitar amp that uses a Tesla coil to create a unique tone and dazzling visuals to go along with it. The amp will take the input from an electric guitar and use this to change the frequency of a tesla coil's sparks onto a grounding rod, creating a tone that matches that of the guitar.

# Solution Components:

## Audio Input and Frequency Processing -

This will convert the output of the guitar into a square wave to be fed as a driver for the tesla coil. This can be done using a network of op-amps. We will also use an LED and phototransistor to separate the user from the rest of the circuit, so that they have no direct connection to any high voltage circuitry. In order to operate our tesla coil, we need to drive it at its resonant frequency. Initial calculations and research have this value somewhere around 100kHz. The ESP32 microcontroller can create up to 40MHz, so we will use this to drive our circuit. In order to output different notes, we will use pulses of the resonant frequency, with the pulses at the frequency of the desired note.

## Solid-state switching -

We will use semiconductor switching rather than the comparably popular air-gap switching, as this poses less of a safety issue and is more reliable and modifiable. We will use a microcontroller, an ESP 32, to control an IR2110 gate driver IC and two to four IGBTs held high or low in order to complete the circuit as the coil triggers, acting in place of the air gap switch. These can all be included on our PCB.

## Power Supply -

We will use a 120V AC input to power the tesla coil and most likely a neon sign transformer if needed to step up the voltage to power our coil.

## Tesla Coil -

Consists of a few wire loops on the primary side and a 100-turn coil of copper wire in order to step up voltage for spark generation. Will also require a toroidal loop of PVC wrapped in aluminum foil in order to properly shape the electric field for optimal arcing. These pieces can be modular for easy storage and transport.

## Grounding rod -

All sparks will be directed onto a grounded metal rod 3-5cm from the coil. The rest of the circuit will use a separate neutral to further protect against damage. If underground cable concerns exist, we can call an Ameren inspector when we test the coil to mark any buried cables to ensure our grounding rod is placed in a safe location.

## Safety -

Tesla coils have been built for senior design in the past, and as noted by TAs, there are several safety precautions needed for this project to work. We reviewed guidelines from dozens of recorded tesla coil builds and determined the following precautions:

* The tesla coil will never be turned on indoors, it will be tested outside with multiple group members present using an outdoor wall outlet, with cones to create a circle of safety to keep bystanders away.

* We will keep everyone at least 10ft away while the coil is active.

* The voltage can reach up to 100kV (albeit low current) so all sparks will be directed onto a grounding rod 3-5cm away, as a general rule of thumb is each 30kV can bridge a 1cm gap.

* The power supply (120-240V) components will be built and tested in the power electronics lab.

* The coil will have an emergency stop button and a fuse at the power supply.

* The cable from the guitar will use a phototransistor so that the user is not connected to a circuit with any power electronics.

# Criterion for Success:

To consider this project successful, we would like to see:

* No safety violations or injuries.

* A tesla coil that produces small visible and audible 3-5cm sparks to our ground rod.

* The coil can play several different notes and tones.

* The coil can take input from the guitar and will play the corresponding notes.

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