Avocados are mischievous fruits that refuse to be overt about their ripeness. Other more upstanding fruits, like the ever reliable apple, display how ripe they are proudly. To tell if an avocado is ripe, you have to give it a few squeezes to see how firm it is. Once an avocado is fully ripe, you only have a few days to eat it before it goes bad (unless you refrigerate). That’s a lot to worry about when you just want some nice avocado toast for brunch, which is why Elad Goldberg and Eden Bar-Tov built this robot to regularly check an avocado and determine when it is ripe.
AvoRipe serves only one purpose: to check how ripe an avocado is. That said, the same hardware could probably be adapted to check the ripeness of many other kinds of fruit. Kiwis, for example, are also notoriously fickle fruit and AvoRipe should be able to check them, too. You check both avocados and kiwis for ripeness in the same way, and color isn’t nearly as important as how firm they are. That’s why this robot has pressure sensors. Those are attached to a pair of 3D-printed fingers that are actuated by a small hobby servo motor. When the fingers squeeze the avocado, those pressure sensors give a fairly reliable reading regarding how firm the fruit is.
That process is automated with a Wemos D1 Mini ESP8266 development board. Blynk IoT software is used to take readings twice a day and then sends those to an Adafruit.IO data feed. Though it isn’t a reliable way to check for ripeness, AvoRipe also uses a color sensor to look at the fruit’s current color. Doing so simply helps validate the data from the pressure sensors. If it is determined that the avocado is ripe, then Blynk will automatically send a notification to the user’s smartphone to let them know. You can then use your avocado to make some delicious toast or guacamole.