Introduction
As engineering students, we’re constantly looking for ways to combine creativity with practical problem-solving — and what better way to do that than by improving a daily ritual: making coffee? Our project is a smart coffee machine that uses time-of-flight sensors to measure cup volume, ensures optimal water temperature during heating, and dispenses the exact milk-to-coffee ratio, no matter the cup’s size or shape.
We noticed that most coffee machines operate on fixed ratios depending on a specific mug type, which can lead to overflows or underfilled cups. We wanted to create a smarter, more adaptable solution that could measure and respond to the cup in real time, making the perfect cup every time.
Our main objectives are to:
- Develop a functional prototype that integrates real-time sensing.
- Use a Raspberry Pi to handle sensor data and control the machine’s operations.
Success will be measured by the machine’s accuracy in volume detection, temperature control, and consistency in delivering the perfect coffee-to-milk ratio.
Project Overview
Our smart coffee machine consists of four core functions:
- Cup Detection and Volume Measurement: Using time-of-flight sensors, the machine detects the cup’s dimensions in real time. This allows the system to calculate the cup’s total volume and adjust the liquid dispensed accordingly.
- Temperature Control: A heating element, monitored by a temperature sensor, ensures the water reaches and maintains the ideal temperature for brewing.
- Weight Measurement:A load cell (weight sensor) measures the weight of the cup and its contents, providing an additional layer of accuracy in liquid dispensing.
- Precise Liquid Dispensing: Based on the calculated volume and desired coffee-to-milk ratio, the machine dispenses the exact amount needed to fill the cup perfectly.
Development Process
Components Used
For our project, we were provided with a Raspberry Pi 5 to control the sensors and other hardware. Code is written in C++ for data processing, decision-making, and hardware control in real time. The key components include:
- Two time-of-flight sensors for cup detection and volume measurement.
- A weight sensor for monitoring the liquid dispensed.
- A temperature sensor for meausring water temperature.
- A motorised lead screw system to move the time-of-flight sensors vertically, capturing the cup’s dimensions at multiple points.
Prototyping
The initial prototype is still under development. Our first step was to understand the inner workings of a standard coffee machine, so we sourced a used machine with sustainability in mind and carefully disassembled it. From there, we identified the parts we could reuse, and the modifications required to suit our design.<
A CAD model of the coffee machine and the additional components was created in Fusion 360, allowing us to visualise our design and plan sensor placement. 3D printing with PLA will be used to build a few custom parts, such as the arms to hold the time-of-flight sensors and a casing for the Raspberry Pi.<
Currently, we’re in the process of setting up and calibrating the sensors on the Raspberry Pi. Once that’s done, we will integrate the mechanical and software components and begin testing. The final phase will involve refining sensor accuracy, optimising the coffee-to-milk ratio, and ensuring the machine dispenses liquid precisely according to the detected cup volume.<
The funding we received from RS Components has been invaluable during this stage, allowing us to purchase quality sensors and additional components for building the prototype.
Results and Impact
Although the project is still in development, we’ve achieved several key milestones:
- Acquiring Components: We successfully sourced the necessary sensors, mechanical components, and a standard coffee machine.
- Modelling Our Prototype in CAD: Building a digital model helped us visualise the final design and plan the integration of new components.
- Setting Up Sensors: We’ve configured the Raspberry Pi to interface with the time-of-flight sensors and the temperature sensor, laying the groundwork for real-time processing.
- Practical Learning:This project has also allowed us to learn more about embedded systems, real-time data processing, and sensor integration. It’s provided hands-on experience that will be valuable in our future engineering careers.
The support from RS Components has been crucial in getting us this far, enabling us to experiment with quality materials and refine our approach.
Conclusion
Our smart coffee machine has the potential to be a valuable addition to smart homes and automation. While this is just the initial prototype, future iterations could feature additional upgrades like an integrated coffee grinder, touchscreen interface, or voice automation. The possibilities are endless, and we hope our machine could one day find a place in every coffee lover’s kitchen.
Beyond the machine itself, this project has been about applying engineering principles to everyday challenges. From learning about real-time applications and sensor calibration to working with Raspberry Pi and mechanical systems, this experience has strengthened our problem-solving skills and deepened our passion for innovation.
If you’re curious to see how our project evolves, follow us on our social media channels below for updates.
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