Project

# Title Team Members TA Documents Sponsor
20 Solar-Powered Traffic Light
Bowen Xiao
Colin Tarkowski
Richard Przybek
Qingyu Li design_document1.pdf
design_document2.pdf
design_document3.pdf
final_paper1.pdf
photo2.jpg
photo1.png
presentation1.pdf
proposal1.pdf
proposal2.pdf
# Solar-Powered Traffic Light

Team Members:
- Colin Tarkowski (colinet2)
- Bowen Xiao (bowenx2)
- Richard Przybek (przybek2)

# Problem
Traffic lights are integral to our society, despite their relative lack of innovation over the years. The most significant change has been the switch from incandescent bulbs to LEDs in an attempt to reduce the power consumption of this necessary device. However, this has also led to an increase of light pollution due to the cooler, more intense light emitted by LEDs. They can cause extreme glare and pose a danger to drivers at night. Additionally, the issue of bicyclists and vehicles sharing the road can create many awkward or dangerous situations due to the lack of separation.

# Solution
We propose a solar-powered traffic light system that will solve the issues of drivers and bicyclists sharing the intersection and of light pollution, in addition to reducing consumption of traditional power in two ways.
A pressure sensor located near the intersection, such as located upon a nearby curb, will detect whether there is a bicyclist present.
Maybe a button instead?
The system will be solar powered to minimize utility power utilized during the day. Connection to the grid will be necessary for operation at night or when solar conditions are suboptimal.
At night, when light pollution is a significant issue, PWM circuitry will correspondingly dim the LED modules by limiting current. This not only reduces light pollution, but also lowers utility consumption at night.

# Solution Components
## Subsystem 1 - Power
The system will be powered with a solar panel and will include a buck/boost converter to regulate the voltage to 24V. The exact voltage of the panel will depend on what is available in the lab, ideally 24V. Solar power will be generated by ECEB solar panels (if possible) or a purchased module. For backup, we will utilize an AC/DC converter to step the 120VAC utility voltage down to 24VDC. We will also need DC/DC converters to 5V and 3.3V to power the microcontroller and sensors.

## Subsystem 2 - Control
This subsystem will include a microcontroller. It will take data from the pressure sensor (or other used for bicyclists), infrared sensor, and photodiode, process it, and change the traffic lights accordingly.

## Subsystem 3 - Traffic Light System
This subsystem will require the aforementioned light modules, all of which can be acquired from a company called Leotek. Their website mentions samples and we hope to be able to utilize the following modules from them:
1x red, 1x yellow, and 3x green 10-28V LED traffic signal modules (see [here](https://leotek.com/wp-content/uploads/IL6-P3_8inch-and-12inch_10-28Vdc_Signal_Ball_Spec_Sheet_07-01-19.pdf)).
- Additional 2 green modules will be for the bicycle and the walk sign
- If we are unable to acquire these modules, we can construct arrays of the desired LEDs that will operate at the same intended voltage of 24VDC. In this case, the bicycle and walk signs will be constructed with cutouts placed over the module that display the desired shape
- A pressure sensor will be utilized to detect when a bicyclist is at the intersection and an infrared sensor will detect whether a car is at the intersection and how many are present. Alternatively, we could use a camera system to run object detection algorithms on cars and bikes (we could accomplish this using an openMV chip, look into openVx applications, or as a last resort run openCV on a raspberry pi)

# Criterion For Success
A successful project will fulfill the following requirements:
- A standard traffic light (red, yellow, green), a walk light, and a bicycle light controlled on a timer with sensors that adjust the sequence and timing
- An infrared sensor will be utilized to detect when a vehicle is in a given area and the light will then turn green. Pedestrians will be able to press a button to trigger a walk sign shortly afterward
- In order to limit light pollution at night, PWM circuitry will be installed to ensure that the LED is dimmed when the ambient light is sufficiently dark. This will reduce light pollution while reducing the power consumed by the traffic light at night
- Connection to 120VAC grid power will be required to operate the system at night or during cloudy days. System should be able to switch smoothly between solar and grid power
- Will detect traffic flow and adjust timing of lights accordingly, in real time. Vehicle numbers will be detected by the infrared sensor and the timing of the traffic light will be altered autonomously to limit traffic congestion
- Be able to withstand typical weather conditions (waterproof, cold and heat resistant)
- OPTIONAL: Provide manual override to blinking red light for emergency situations
- OPTIONAL: Incorporate MPPT and develop software that will rotate the solar panel along a single access to maximize solar power consumption during the day. This will minimize the need for grid power around dawn and dusk

# Note
A system will only be developed for one of the four directions of the intersection, as the other three would simply require equivalent or complementary function. This will also reduce cost and help the project to stay within budget.

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.