In most bubble tea shops, the amount of boba added to each cup is not exact. Instead, it is usually a rough estimate depending on the preferences selected when ordering. It could even be said that no two cups have the same number of boba. For our bubble tea machine, we had initially wanted to dispense an exact amount of boba into each cup. However, it was extremely difficult to do so as bobas come in different shapes and sizes and an individual boba can vary significantly from another.
(Credits: Bubble Panda)
When we were trying to determine the amount of boba dispensed by our machine, we realised that we did not need each cup to have the exact amount of boba. We decided to use an estimate in all the cups as a more ideal method of dispensing the boba. However, we also wanted to make sure that the difference in amount of boba between each cup is small such that one cup does not end up having a lot more boba than the other.
Hence, instead of measuring the amount of boba dispensed through the number of bobas, we decided to use weight. The recommended serving size of boba for a drink of 450 ml was around 83 grams, so we used that weight as the target weight of boba to be dispensed. The dispensing involved the auger spinning due to the rotation of the stepper motor until it hit 83 grams of boba in the cup.
We programmed this weight into our code on Arduino IoT such that it will give instructions to the stepper motor to rotate when the boba needs to be dispensed until the load cell has weighed at least 83 grams of boba within the cup. When we dispensed this weight of boba using IoT, we realised that it was very similar to the amount given usually in bubble tea shops, allowing us to resolve the last issue we had regarding the dispensing of boba.