Course Overview :: ECE 445 - Senior Design Laboratory

Welcome!

Welcome to ECE 445! If you've looked at the course Calendar, you've probably already noticed that this class is quite different from most other classes in the department. The class only meets as a whole for the first few weeks of the semester. During these lectures you will meet the Course Staff, learn about specific assignments, requirements, and resources for the course, and have a chance to meet other students to share ideas and form teams. These are some of the most important weeks for the class since the decisions you make during this time will determine what you'll get out of this class and, in many ways, how much you'll enjoy it.

Outside of lecture, you are expected to be working on your own to develop ideas and form teams. You are also expected to actively participate on the web board to exchange ideas, receive feedback from course staff, and eventually get your project idea approved. Once your team has a project approved, you will be assigned a TA, with whom you will have weekly meetings. Think of your TA as a project manager. Keep in mind that they are not there to do the work for you. Rather, they are there to keep you on track, point you towards resources (both within and outside of the department), and evaluate the result of your efforts.

Expectations and Requirements

We have high expectations for students participating in ECE 445. You are soon to be alumni of one of the top ECE departments of the world. Our alumni hold themselves to high technical and professional standards of conduct. In general, projects are expected to be safe, ethical, and have a level of design complexity commensurate with the rigor of the ECE Illinois curriculum. Requirements for specific assignments due throughout the semester can be found by looking through the Grading Scheme for the course. Please read through this documentation well before each assignment is due. Specific due dates can be found on the course Calendar.

Below are a few words of wisdom to keep in mind throughout the semester to increase your enjoyment and success in the course:

"You don't get harmony when everybody sings the same note" (attributed to Doug Floyd). You might be tempted to form a team exclusively of your friends you have worked with in previous courses. While it is important to make sure you can have a good working relationship with your teammates, it is equally important to make sure that your team consists of engineers with a wide range of skill sets. If you are only working with people who have taken courses with in the past, you likely will have overlapping skill sets and the same technical blindspots. Consider talking with other students who have taken courses in areas you have not. You might find that the combination of these disparate skill sets lend themselves to creating a more exciting project!

"With great freedom comes great responsibility" (attributed to many, including Benjamin Franklin). In this course, you are ultimately responsible for the success of your project. To a very large extent, you define your own requirements and metrics for success. Although the course staff is there to support and encourage you, you and your teammates must put in the time and effort that will lead to a successful demonstration of your project at the end of the semester. However, seek out and carefully consider the advice provided to you by the course staff. We tend to have a good sense of what is and is not possible within the constraints of the course.

"Slow and steady wins the race" (from an Aesop's fable). You will actually be constructing and physically demonstrating the project you design in this course. Creating a schedule that distributes work amongst your team throughout the semester, and sticking to it, is paramount! Please do not leave things until the end of the semester and expect a positive outcome. Procrastination is not your friend, for no other reasons than parts take time to order and arrive, the electronics and machine shops get inundated with requests from this and other courses and so may not be able to immediately address your needs, and the lab can get very crowded and you may not be able to access a lab bench whenever you want.

"You catch more flies with honey than you do with vinegar" or "Treat others the way you expect to be treated" (attributed to many). Conducting yourself professionally will take you far in this course. Be considerate to your teammates, TA, and anyone else you interact with in this course (and in life, for that matter!). Your TA will be working with many groups in addition to yours. Be respectful of their time. If you are going to be late or miss a meeting with them, contact them as soon as you know this so they can repurpose their time. Get in touch with the electronics and machine shop as early as possible if you are going to need their services and seek their advice. Be considerate of your teammates and others in the course - clean up lab benches, log off of computers when not in use, don't hog test equipment, help others if they ask. You will find that this department is filled with people who will bend over backwards to help you succeed, and this help will be given happily if they are treated respectfully.

Featured Project

# Illini Voyager

Team Members:

- Christopher Xu (cyx3)

- Cameron Jones (ccj4)

# Problem

Weather balloons are commonly used to collect meteorological data, such as temperature, pressure, humidity, and wind velocity at different layers of the atmosphere. These data are key components of today’s best predictive weather models, and we rely on the constant launch of radiosondes to meet this need. Most weather balloons cannot control their altitude and direction of travel, but if they could, we would be able to collect data from specific regions of the atmosphere, avoid commercial airspaces, increase range and duration of flights by optimizing position relative to weather forecasts, and avoid pollution from constant launches. A long endurance balloon platform also uniquely enables the performance of interesting payloads, such as the detection of high energy particles over the Antarctic, in situ measurements of high-altitude weather phenomena in remote locations, and radiation testing of electronic components. Since nearly all weather balloons flown today lack the control capability to make this possible, we are presented with an interesting engineering challenge with a significant payoff.

# Solution

We aim to solve this problem through the use of an automated venting and ballast system, which can modulate the balloon’s buoyancy to achieve a target altitude. Given accurate GPS positioning and modeling of the jetstream, we can fly at certain altitudes to navigate the winds of the upper atmosphere. The venting will be performed by an actuator fixed to the neck of the balloon, and the ballast drops will consist of small, biodegradable BBs, which pose no threat to anything below the balloon. Similar existing solutions, particularly the Stanford Valbal project, have had significant success with their long endurance launches. We are seeking to improve upon their endurance by increasing longevity from a power consumption and recharging standpoint, implementing a more capable altitude control algorithm which minimizes helium and ballast expenditures, and optimizing mechanisms to increase ballast capacity. With altitude control, the balloon has access to winds going in different directions at different layers in the atmosphere, making it possible to roughly adjust its horizontal trajectory and collect data from multiple regions in one flight.

# Solution Components

## Vent Valve and Cut-down (Mechanical)

A servo actuates a valve that allows helium to exit the balloon, decreasing the lift. The valve must allow enough flow when open to slow the initial ascent of the balloon at the cruising altitude, yet create a tight seal when closed. The same servo will also be able to detach or cut down the balloon in case we need to end the flight early. A parachute will deploy under free fall.

## Ballast Dropper (Mechanical)

A small DC motor spins a wheel to drop [biodegradable BBs](https://www.amazon.com/Force-Premium-Biodegradable-Airsoft-Ammo-20/dp/B08SHJ7LWC/). As the total weight of the system decreases, the balloon will gain altitude. This mechanism must drop BBs at a consistent weight and operate for long durations without jamming or have a method of detecting the jams and running an unjamming sequence.

## Power Subsystem (Electrical)

The entire system will be powered by a few lightweight rechargeable batteries (such as 18650). A battery protection system (such as BQ294x) will have an undervoltage and overvoltage cutoff to ensure safe voltages on the cells during charge and discharge.

## Control Subsystem (Electrical)

An STM32 microcontroller will serve as our flight computer and has the responsibility for commanding actuators, collecting data, and managing communications back to our ground console. We’ll likely use an internal watchdog timer to recover from system faults. On the same board, we’ll have GPS, pressure, temperature, and humidity sensors to determine how to actuate the vent valve or ballast.

## Communication Subsystem (Electrical)

The microcontroller will communicate via serial to the satellite modem (Iridium 9603N), sending small packets back to us on the ground with a minimum frequency of once per hour. There will also be a LED beacon visible up to 5 miles at night to meet regulations. We have read through the FAA part 101 regulations and believe our system meets all requirements to enable a safe, legal, and ethical balloon flight.

## Ground Subsystem (Software)

We will maintain a web server which will receive location reports and other data packets from our balloon while it is in flight. This piece of software will also allow us to schedule commands, respond to error conditions, and adjust the control algorithm while in flight.

# Criterion For Success

We aim to launch the balloon a week before the demo date. At the demo, we will present any data collected from the launch, as well as an identical version of the avionics board showing its functionality. A quantitative goal for the balloon is to survive 24 hours in the air, collect data for that whole period, and report it back via the satellite modem.

![Block diagram](https://i.imgur.com/0yazJTu.png)