week 16

System Integration

• Design and document the system integration for your final project

Design

This week involved making important decisions about the project. The first step I took was to create a diagram illustrating the system integration of my project.
At first, I wasn’t sure how I was going to integrate all the components.

PCB

Since I hadn’t yet designed the PCBs, that was the first thing I tackled. You can find the detailed PCB design on the final project page.

PCB 1

This PCB serves as the central hub for data acquisition and communication within the system. It collects real-time data from multiple sensors, ensuring accurate monitoring of environmental and operational conditions. The gathered data is then transmitted wirelessly to a remote server, where it can be accessed and visualized through a mobile phone or tablet, providing an intuitive and user-friendly interface. Additionally, the PCB establishes a Wi-Fi connection with the control unit, enabling seamless integration and responsive interaction between sensing, data processing, and actuation components.

BOM:

This PCB acts as a bridge between the HX711 and the rest of the system. It ensures a secure and stable connection for the load cells, helping maintain data accuracy. Each load cell will have its own dedicated PCB, making the system more organized, easier to manage, and reducing the risk of interference.

PCB for load cells

BOM:

PCB 2: Controller

This PCB is designed to allow control and interaction with the system. Once powered on, it connects automatically to PCB 1, enabling the user to configure and calibrate the system depending on what needs to be measured. It will feature a simple menu interface and includes an environmental temperature and humidity sensor, which can be used to compare with the internal moisture levels of the wood.

It also includes a potentiometer for menu navigation, an OLED screen, a power switch, a button, and the temperature/humidity sensor.

BOM:

Once I had the dimensions, I began designing their packaging.

Packaging

For the packaging, I used the same base box design for all components. Since the PCBs and sensors vary in size, I used Grasshopper to adapt the design accordingly.

Load cells

For the load cells, I created the following diagram:

The purpose of the load cell is to detect any moment or rotational force at a joint. If such a force is detected, it could indicate the presence of a hinge, potentially leading to a local or even global structural failure. To ensure accurate readings, 3D-printed components will be used to apply a counterforce to the load cell, as it operates by sensing bending forces.

Moisture Sensor

This moisture sensor uses two metal nails inserted into a piece of wood, creating a basic resistive sensor. It measures electrical conductivity, which changes with the wood’s moisture content. One nail connects to ground, and the other to a voltage divider made with a 10kΩ resistor and the 5V supply. The midpoint of the divider is read by an ADC pin on the Xiao ESP32C3 microcontroller. As the wood’s moisture level changes, so does its resistance, altering the voltage and allowing the system to estimate moisture content.

Wiring

For the wiring, I’ll use a ribbon cable 8257523.

To attach the cables to the bridge, I’ll use a wire mount developed by Angelina Yang

Data visualization

To visualize the data, I will develop an interface that displays acceleration values, wood moisture, ambient humidity and temperature, as well as the readings from each load cell. A smartphone or tablet will connect to the ESP32 via Wi-Fi, allowing real-time access and interaction with the data.

Documentation