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Automated Tea Brewer

2016-06-01 | By Joshua Bishop

License: General Public License

Overview

At its simplest, tea brewing is very straightforward.  Take water, add heat, add tea, done.  However, depending on the type of tea, the water needs to be at a certain temperature and it needs to steep a specific amount of time to achieve an ideal cup.  Get either of these factors off and the tea is weak or too strong or bitter.  So we decided to automate the process as much as possible while still giving the option of using real tea leaves instead of vacuum packed cups or packets.

Approach

For our project, the tea brewer will sit on the side of the cup of tea.  The idea is to have a mesh tea leaf holder that is then placed into and pulled out of the water at the appropriate temperature after steeping for the appropriate time.  This mesh tea leaf holder will be moved by a small servo motor.   A small temperature gauge will be a part of the cup holder that will be low enough to constantly be in the water.  When hot water is directly added, the tea brewer will wait until it has cooled to the appropriate temperature before putting in the tea.  If the cup is being directly heated, the tea brewer will put the tea in once the water has reached the appropriate temperature.  In this scenario, the user will be required to turn off the heat source so that water does not get too hot.  After the tea has steeped long enough, the motor will pull the leaves out of the water.

To simplify the controls, the entire device will be programmed with an app via BLE, or Bluetooth Smart.  Variables for different types of tea will be programmed in and can be selected in the app.  Another feature in the app will be a single button on the device itself which can be set as a “favorite” button to brew the most commonly brewed tea without the app.

Challenges and Design Considerations

Any interaction with the physical world can be a challenge as there are always variables that cannot be controlled.  While a servo motor is extremely easy to control, there was a lot of discussion on whether there should be any sort of feedback to make sure there was no harm or damage in the operation of the motor.  After much debate, it was decided that there would be no feedback at this point.  If the prototype showed that additional measures were needed, we would implement them at that time.  However, due to the small size of the servo motor, the only damage we feared was it overloading itself, so we anticipate putting a current sensor to cut-out the motor if it is drawing excessive or damaging levels of power.

Another challenge was integrating the BLE, as we’d only used first generation Bluetooth up until this point.  We found that the modules available made interfacing with the BLE module much easier than we were anticipating, while also having FCC pre-certification.  Despite our concerns, this turned into practically a non-issue.

While we have quite a bit of design experience with firmware creation for embedded systems, the app design was a bit of a challenge.  We were able to make a functional, if utilitarian interface, but we would almost certainly want an expert app designer to make a sleek, easy-to-use and attractive interface.

As we have limited mechanical experience as well, we were worried about balancing issues as well as making sure the hardware was firmly attached to the side of the cup.  This required a bit of trial and error, but the original hardware we planned on using was used with only minor modifications.

End Result

In the end, the tea brewer works exactly as intended.  While not a particularly elegant piece of hardware, it is fully functional and brews tea exactly according to recommended specifications.  All in all, it worked as a perfect proof-of-concept, showing that the brewing of tea could be exact, flexible in time and temperature, while avoiding proprietary sources of tea leaves.

Moving Forward

There isn’t much we’d change from the top-level, though we’d likely want to make many minor changes to improve reliability and aesthetics, reduce costs and perhaps tweak the app interface for ease of use.  We’re currently in discussions to see if there is a sufficient market for this device as it is, if we’ll need to make any design changes due to user requirements versus technical reasons, if there are any potential legal issues and costs associated with scaling this design up to full production.

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