Project

# Title Team Members TA Documents Sponsor
67 Automatic Water Quality Monitoring using Test Strips
Abdullah Alsufyani
Fahad Alsaab
Jiankun Yang design_document1.pdf
final_paper1.pdf
other1.pdf
presentation1.pdf
proposal1.pdf
# Automatic Water Quality Monitoring using Test Strips

Team Members:
- Fahad AlSaab (fahadma)
- Abdullah AlSufyani (aaa25)

# Problem

Using water quality testing strips to identify key characteristics can be time-consuming. Each color strip can have different color scales and varying wait times before the chemical agent provides valid results. While it is true that some tests, such as pH, have digital alternatives, these alternatives tend to be more expensive, often require additional calibration, and sometimes do not exist for certain chemical tests. Consequently, automating water quality testing across a wider range of chemicals and substances continues to rely on test strips.


# Solution

Our solution is an automated system that applies water to a test strip and records its values. The enclosed system consists of a mechanism to dispense water onto a test strip. It then waits for the chemical reactions to complete and reads the color results using sensors. A mechanism will replace the used test strips with a fresh one from a storage stack, ensuring multiple days to weeks worth of testing before needing user replacement.

Water will be dispensed using a solenoid, with water sourced either from a reservoir or a home water inlet. The colors will be measured using either color sensors or a digital camera, with LED illumination for consistency. This system enables automated daily monitoring with fresh water samples compared to other water quality testing designs. It expands the range of testable chemicals by leveraging traditional test strips while maintaining affordability by avoiding expensive digital water sensors. The system will be evaluated based on its ability to reliably execute the testing cycle and the accuracy of its color reading compared to human observations.


# Solution Components

## Test Strip Storage Cartridge

This subsystem stores and dispenses test strips. The strips are stacked vertically and dispensed using a roller mechanism similar to a printer. The cartridge ensures that a fresh test strip is available for each test cycle.

### Components
Motorized roller mechanism
Vertical test strip storage compartment
Sensor to detect the presence of test strips.


## Feeder System

The feeder system transports test strips from the storage cartridge to the testing chamber, It ensures proper alignment and positioning of the strip for water application and water detection.


### Components

Stepper motor with precision control
Guide rails for strip movement
Optical sensor for strip alignment verification
Adafruit Motor Shield (https://www.adafruit.com/product/169)

## Water Reservoir and Droplet Dispenser

### Components:
Solenoid valve for controlled water dispensing
Water reservoir with level sensor
Tubing and nozzle for precise droplet application


## Test Strip Color Sensor

This module measures the color of each square of the test strip and has illumination via onboard LEDs to make reading the color more accurate. We will use a color-sensing chip to test its accuracy first and switch to a conventional camera if we do not get the accuracy we want.

The TCS3472 color light to digital converter chip provides us with color measurements.

### Components:
RGB color sensor (e.g., The TCS3472 color light to digital converter chip provides us with color measurements.)
LED illumination for consistent lighting

## Displaying Results

Print over serial USB connection the measured concentrations of chemicals and minerals found in the water.

## Power System

Powered from a standard wall outlet using an AC to DC converter.

# Criterion For Success

1. The cartridge system is reliably able to dispense test strips to the feeder system. Able to do at least 5 water quality testing cycles automatically without jamming.
2. The feeder system can move and position the test strip underneath the water droplet dispenser and color sensor within half a centimeter.
3. The water droplet dispense system can dispense exactly one drop of water at a time accurately onto the square chemical papers such that the test square is fully saturated.
4. The color sensing system can accurately determine the concentration for each test within 10% accuracy compared to a human’s reading of the same test strip.
5. The system can reliably store used test strips in a removable container for the user to dispose.

ATTITUDE DETERMINATION AND CONTROL MODULE FOR UIUC NANOSATELLITES

Shamith Achanta, Rick Eason, Srikar Nalamalapu

Featured Project

Team Members:

- Rick Eason (reason2)

- Srikar Nalamalapu (svn3)

- Shamith Achanta (shamith2)

# Problem

The Aerospace Engineering department's Laboratory for Advanced Space Systems at Illinois (LASSI) develops nanosatellites for the University of Illinois. Their next-generation satellite architecture is currently in development, however the core bus does not contain an Attitude Determination and Control (ADCS) system.

In order for an ADCS system to be useful to LASSI, the system must be compliant with their modular spacecraft bus architecture.

# Solution

Design, build, and test an IlliniSat-0 spec compliant ADCS module. This requires being able to:

- Sense and process the Earth's weak magnetic field as it passes through the module.

- Sense and process the spacecraft body's <30 dps rotation rate.

- Execute control algorithms to command magnetorquer coil current drivers.

- Drive current through magnetorquer coils.

As well as being compliant to LASSI specification for:

- Mechanical design.

- Electrical power interfaces.

- Serial data interfaces.

- Material properties.

- Serial communications protocol.

# Solution Components

## Sensing

Using the Rohm BM1422AGMV 3-axis magnetometer we can accurately sense 0.042 microTesla per LSB, which gives very good overhead for sensing Earth's field. Furthermore, this sensor is designed for use in wearable electronics as a compass, so it also contains programable low-pass filters. This will reduce MCU processing load.

Using the Bosch BMI270 3-axis gyroscope we can accurately sense rotation rate at between ~16 and ~260 LSB per dps, which gives very good overhead to sense low-rate rotation of the spacecraft body. This sensor also contains a programable low-pass filter, which will help reduce MCU processing load.

Both sensors will communicate over I2C to the MCU.

## Serial Communications

The LASSI spec for this module requires the inclusion of the following serial communications processes:

- CAN-FD

- RS422

- Differential I2C

The CAN-FD interface is provided from the STM-32 MCU through a SN65HVD234-Q1 transceiver. It supports all CAN speeds and is used on all other devices on the CAN bus, providing increased reliability.

The RS422 interface is provided through GPIO from the STM-32 MCU and uses the TI THVD1451 transceiver. RS422 is a twisted-pair differential serial interface that provides high noise rejection and high data rates.

The Differential I2C is provided by a specialized transceiver from NXP, which allows I2C to be used reliably in high-noise and board-to-board situations. The device is the PCA9615.

I2C between the sensors and the MCU is provided by the GPIO on the MCU and does not require a transceiver.

## MCU

The MCU will be an STM32L552, exact variant and package is TBD due to parts availability. This MCU provides significant processing power, good GPIO, and excellent build and development tools. Firmware will be written in either C or Rust, depending on some initial testing.

We have access to debugging and flashing tools that are compatible with this MCU.

## Magnetics Coils and Constant Current Drivers

We are going to wind our own copper wire around coil mandrels to produce magnetorquers that are useful geometries for the device. A 3d printed mandrel will be designed and produced for each of the three coils. We do not believe this to be a significant risk of project failure because the geometries involved are extremely simple and the coil does not need to be extremely precise. Mounting of the coils to the board will be handled by 3d printed clips that we will design. The coils will be soldered into the board through plated through-holes.

Driving the inductors will be the MAX8560 500mA buck converter. This converter allows the MCU to toggle the activity of the individual coils separately through GPIO pins, as well as good soft-start characteristics for the large current draw of the coils.

## Board Design

This project requires significant work in the board layout phase. A 4-layer PCB is anticipated and due to LASSI compliance requirements the board outline, mounting hole placement, part keep-out zones, and a large stack-through connector (Samtec ERM/F-8) are already defined.

Unless constrained by part availability or required for other reasons, all parts will be SMD and will be selected for minimum footprint area.

# Criterion For Success

Success for our project will be broken into several parts:

- Electronics

- Firmware

- Compatibility

Compatibility success is the easiest to test. The device must be compatible with LASSI specifications for IlliniSat-0 modules. This is verifiable through mechanical measurement, board design review, and integration with other test articles.

Firmware success will be determined by meeting the following criteria:

- The capability to initialize, configure, and read accurate data from the IMU sensors. This is a test of I2C interfacing and will be tested using external test equipment in the LASSI lab. (We have approval to use and access to this equipment)

- The capability to control the output states of the magnetorquer coils. This is a test of GPIO interfacing in firmware.

- The capability to move through different control modes, including: IDLE, FAULT, DETUMBLE, SLEW, and TEST. This will be validated through debugger interfacing, as there is no visual indication system on this device to reduce power waste.

- The capability to self-test and to identify faults. This will be validated through debugger interfacing, as there is no visual indication system on this device to reduce power waste.

- The capability to communicate to other modules on the bus over CAN or RS422 using LASSI-compatible serial protocols. This will be validated through the use of external test equipment designed for IlliniSat-0 module testing.

**Note:** the development of the actual detumble and pointing algorithms that will be used in orbital flight fall outside the reasonable scope of electrical engineering as a field. We are explicitly designing this system such that an aerospace engineering team can develop control algorithms and drop them into our firmware stack for use.

Electronics success will be determined through the successful operation of the other criteria, if the board layout is faulty or a part was poorly selected, the system will not work as intended and will fail other tests. Electronics success will also be validated by measuring the current consumption of the device when operating. The device is required not to exceed 2 amps of total current draw from its dedicated power rail at 3.3 volts. This can be verified by observing the benchtop power supply used to run the device in the lab.