This Watermelon Bot Hides in Plain Sight

Michael Bay may have run the Transformers franchise into the ground and most of us would be happy if we never saw another one of those movies, but there were some fun scenes here and there. In particular, it was cool to see innocuous objects unfold themselves into complex robots. For instance, wouldn’t you love to see a watermelon transform into a robot that can scramble around your kitchen floor? Good news! You can, thanks to Ryota Kobayashi’s Sherobo project.

Sherobo is a “Spherical Quadruped Robot” that looks like a simple ball when it isn’t active. Kobayashi built a couple of them with coats of green paint and dark stripes, so they look like watermelons. But Sherobo could look like other fruits, too. Cantaloupe? Easy. Pumpkin? Child’s play—and yes, that’s a fruit. Orange? Sure, if you place it really far away from the camera to make it look smaller than it is.

And Sherobo isn’t all aesthetics; it is a fairly capable quadrupedal robot. Each leg has 3DoF, so it has a decent amount of dexterity. Quadrupedal gaits are difficult to optimize and this design posed an additional challenge because the legs are radially symmetrical. Instead of walking like a graceful mammal, Sherobo has more of a scurrying crablike movement. But you won’t mind when you see it curl up into a ball or spring back into robot form.

Each robot has an M5Stack ATOM Lite development board with ESP32 microcontroller. That connects to the 12 Feetech SCS0009 servo motors through a custom control board. There is also a ring of LEDs on the bottom for some extra flair. Power comes from a pair of batteries in a holder, though the write-up doesn’t specify what kind of batteries those are. It looks like it may use an 18650 lithium battery holder.

Sherobo’s body/legs are 3D-printed, as is its internal frame structure. As designed, the outer body shell is a sphere split into four segments. That means that the paint job is the primary means by which a Sherobo robot camouflages itself. Paint it like a watermelon and it will look like a watermelon. Paint it like a basketball and it will look like a basketball.

But the possibilities are almost endless. We think a Death Star Sherobo would look really cool.