Fully Automated Coffee Machine

Team Project: 2021 Fall

By Ivan Shao,

Junlong Li,

Zelin Ye

1. Background and Motivation

The initial goal of this project is to create a relatively low-cost, smart drink-making appliance for everyday life. The machine is also designed to save time from operating machines and handles the simple repetitive actions when it comes to making customized drinks. There are products on the market that produce customizable beverages for customers, but they mostly remain in shopping malls and other public spaces, with the intention to attract nearby consumers. We looked to build a machine that is capable of making coffee, boba, etc. with a custom ratio of different ingredients at home, simply with a few touches with the fingers.

2. Implementations

Our automatic coffee machine can be divided into two subsystems. There is a control panel section that allows the user to customize their inputs such as the ingredients ratio (with the option of less, normal, or more), which is controlled by the amount of time the solenoid stays open (will be mentioned later in the manual). We originally wanted to also incorporate water heating features as well, but did not find a way to build and incorporate into our controls in a timely manner.

Once the user inputs all the necessary commands and press start, the operating section of the coffee machine will start to make coffee. The lower operating section contains a roller carriage and a platform where the cup will be placed. The platform carries a cup and moves along a straight T-rail, making stops at the proper positions to allow the ingredients to be dropped into the cup. moves across a T-rail.

There is a pressure or weight sensor under the cup holder. It can be used to sense if there is a cup on the platform (safety feature). The machine will not continue to operate at any given time when the cup is being removed during the process or drink making. In the upper operating section, there are three boxes that contain the powdered ingredients, and a tube that is connected to a water pump that delivers water to the cup after loading the ingredients. The only differences we had compared to our original design was that the ingredient boxes are in line instead of a rotating disc, and that ultrasonic sensors were not implemented as a safety feature due to compatibility issues with a version of the Arduino UNO board we tried to use.

We also hoped to use PWM to adjust the output voltage of a 12V motor to control its speed, since it is desired to move the platform at a slow and steady speed. But we realized the specific motor required 1.5A of current in order to operate as it has really high torque, and wiring it to the rest of the circuit would have very concerning issues (a fried ESP32).

State Transition Diagram

Circuit Design Detail

3. Closing Remark

In this project, I was responsible for sensor data analysis, software development, circuit design and setup, and prototyping. in the future update and development, instead of using two micro controller, we will use PCB layout design to integrate the circuit elements. Besides that, remove all the lever switches and replace DC motor to stepper motor will upgrade the position control accuracy. In the idealize (unlimited budget) version, changing a touch screen displayer and implementing a online app can be use to improve the user experience.

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