Project

# Title Team Members TA Documents Sponsor
24 Automatic Mirror for Plant Lighting
 Lucian Bell
Mateus Trigo
Sanghoon Kim
 Tianda Huang design_document1.pdf
proposal1.pdf
Team Members:

Lucian Bell (lb25)

Mateus Trigo (mtrigo2)

Sanghoon Kim (sk82)

Problem:

There are many times where an apartment or room does not have a south-facing window, but the resident may want to grow a plant that requires direct sunlight to thrive. Light from an east, west, or north facing window may be adequate for a full-shade plant, but a partial-sun or full-sun plant may not be getting enough direct sunlight. This is a greater issue during winter in the northern hemisphere, where the sun shifts southward in the sky and the hours of daylight decrease. If there was a way for plants in non-south facing windows to get a few more hours of direct sunlight, then full-sun and partial-sun plants could be successfully grown in these windows which would give the resident more freedom to customize their room.

Solution:

We will build a device that uses a sun-tracking flat mirror to redirect sunlight towards the plant in a non-south facing window or other shady space. The device will be powered by a battery, which will allow it to be mounted outside of a window or be placed on a yard or deck. It will use a GPS signal and compass to determine the time, location, and orientation of the device. This data will be used by a microcontroller to determine the position of the sun in the sky relative to the device. On setup, the device will be calibrated to reflect the sun at the desired angle, and the microcontroller will move the mirror to continue reflecting the sun at this angle. The mirror will be attached to a rod with a base, and be controlled by two stepper motors to allow the mirror to change its orientation. The base will rotate to allow for rotation parallel to the ground and there will be a motor near the top of the rod that allows for rotation perpendicular to the ground. The device will also use a light sensor to determine when it is night time or the weather is poor so that it can save energy. This device will be able to provide the extra sunlight that some plants need to thrive in shady spaces.

Main Components:

Motors and Frame

The frame for the device will consist of a base, a rod, and the mirror itself. One stepper motor will be used to rotate the base to allow for rotation parallel to the ground. Another stepper motor will be used near the top of the rod to allow the mirror to rotate perpendicular to the ground. The stepper motors we are planning on using are 17HS15-1504-ME1K, which include rotational encoders to ensure the motor’s rotation is accurate. DRV8434 stepper motor drivers will also be used to convert the low voltage and current signals from the MCU to higher voltage and current signals for the motors.

Sensors

The device will use multiple sensors to determine the position, orientation of the device, light level, and time. All of these sensors will be attached to the PCB and will use I2C serial communication to send signals to the microcontroller. The LIS2MDL sensor is a compass, and will be used by the device to find magnetic north. The microcontroller will use this to convert the rotation of the base to real-world cardinal directions. The MAX-M10S-00B sensor will receive a GPS signal and send the time, latitude, and longitude to the MCU. These signals will be used by the MCU to determine the position of the sun in the sky. The final sensor is the VEML7700-TT light sensor, which will be used to measure the amount of light the device is receiving. This will allow the device to stop rotating in bad weather or at night, which will help it to save energy.

Microcontroller and Firmware

We will use a STM32G071CBT6 microcontroller mounted to the PCB to control the device and process signals from sensors. This microcontroller is low-power since keeping track of the sun position and light level is not computationally intensive, and this will reduce the cost and power consumption of the device. It also has support for I2C serial communication, which we will use to communicate with the sensors. We will write firmware for the microcontroller in C/C++ to make effective use of its small program memory. The firmware will include calibration behavior to calculate the target angle for the reflected light based on the mirror’s current position and the position of the sun. A button or other interface will be added to the PCB to start the calibration process. The firmware will use equations to convert the time, latitude, and longitude from the sensors to the sun’s angle in the sky, and it will position the mirror so that the sun’s light will be reflected to the target angle. If the sun is at a position that can’t be reflected to the target angle, the motors will not move and the device will wait for the sun to move to a position that can be reflected to the target angle. The firmware will also use the light level from the sensors to determine if the motors should not be moved during bad weather or at night to save energy.

Power

The device will use an 3.6V 18650 lithium-ion battery cell for power to accommodate the high-current requirements of the motors. The use of a battery will allow our device to operate outside and further from electrical outlets, which gives the device more flexibility. It is also more convenient than using a power cable, since the user will not have to worry about cable management. To meet the needs of different voltage components, our device will also step up (boosting) and step down (buck) circuits to convert the battery voltage to higher and lower voltages.

Criteria for Success:

Our device will be tested on a flat surface outside with multiple marked targets to measure the accuracy of its light reflection. Alternatively, if the weather is poor, a laser or artificial light can be shined from the sun’s angle in the sky to simulate the sun indoors. The first set of tests are meant to evaluate the device’s ability to calculate the position of the sun and target point accurately. The second set of tests are meant to evaluate the device’s ability to correctly move the mirror to reflect light to a given target point and to evaluate correct sensor behavior.

Sun Position and Target Point Calculation:
1. The device should be able to calculate the position of the sun to within 5 degrees of error to the known position of the sun at the current time and location.
2. The device should be able to calculate the position of the sun to within 5 degrees of error to the known position of the sun at 2 different simulated positions and 2 different simulated times.
3. The device should be able to determine the angle of the target during calibration within 5 degrees of error to the real target.


Real-World Performance:
1. The device should be able to successfully reflect light from the simulated or real sun to a manually entered target point at three different times in the day.
2. The device should be able to run for three hours and keep light from the simulated or real sun on the manually entered target point for 90% of the time.
3. The device should not move the motors when a manually entered target point is outside of the mirror’s reflection range within 5 degrees of error.
4. The device should stop moving the motors if the light sensor is covered.
5. The device should be able to determine the cardinal direction of the mirror’s focus within 5 degrees of error.

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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