Soft Robotic Jellyfish Get Pumped In The Atlantic

In a recent paper in Bioinspiration & Biomimetics, researchers at Florida Atlantic University describe the process of building and testing five free-swimming soft robotic jellyfish. The paper contains build details and data on how three different variables – tentacle stiffness, stroke frequency, and stroke amplitude – affect the swimming characteristics of each bot. For a more in-depth build log, we found the original masters thesis by Jennifer Frame to be very thorough, including processes, schematics, parts lists, and even some Arduino code.

Though a landlubber may say the robots look more like a stumpy octopus than a jellyfish, according to the paper the shape is actually most similar to a juvenile “ephyra stage” moon jellyfish, with 8 short tentacles radiating from a central body. The flexible tentacles are made of a silicon rubber material from Smooth-On, and were cast in 3D printed molds. Inside the waterproof main body is a Teensy 3.2 microcontroller, some flash memory, a nine-axis IMU, a temperature sensor, and a 9 V battery.

There are two flexible resistors embedded in the body to measure tentacle flex, and the actual flexing is done by pumping seawater through open circuit hydraulic channels cast into the tentacles. Two 3 V mini pumps are sufficient for pumping, and the open circuit means that when the pumps turn off, the tentacles bleed off any remaining pressure and quickly snap back to their “neutral” position without the use of complicated valves.

Another simple feature is two hall effect sensors that were mounted in the body to enable waterproof “wireless communication” with the microcontroller. The wireless protocol of choice: manually waving magnets over the sensors to switch the robot between a few predefined operating modes.

There’s a soothing, atmospheric video after the break, where you can see the robots in action off the coast of Florida.

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JumpRoaCH Is Kind Of Cute, Kind Of Creepy

There’s a theory that the fear of scurrying things is genetic. Likewise, a similar theory arose about the tendency for humans to find helpless things cute. After all, our useless babies do best in a pest free environment. This all could explain why we found this robotic roach to be both a little cute and a little creepy.

The university sponsored project, JumpRoaCH, is a collaboration between South Korea’s SNU Biorobotics Lab and Berkeley’s Biomimetic Millisystems Lab. Imitating insects has been a popular avenue for robotic research, and often results in very interesting experiments.

This robot looks like a ladybug going through its rebellious teen phase. It runs on six hook shaped legs which allow it to traverse a wider array of surfaces than wheels would, at the expense of speed and higher vibrations. The robot does a very convincing, if wobbly, scurry across the surface of its test table.

It also has a secret attack in the form of a single Rockem Sockem Robot arm located on its belly. With a powerful burst, the arm can launch the robot up a few feet to a higher surface. If the robot lands on its wheels the researchers high-five. If the robot lands on its back, it can use its ,”wings,” to flip itself right-side-up again.

The resulting paper (PDF file) has a nice description of the robot and its clever jumping mechanism. At least if these start multiplying like roaches, hackers will never short for tiny motors for their projects. Video after the break.

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