[Festo] have come up with yet another amazing robot, a swimming one this time with an elegant propulsion mechanism. They call it the BionicFinWave. Two fins on either side almost a body-length long create a wave which pushes water backward, making the robot move forward. It’s modeled after such fish as the cuttlefish and the Nile perch.
What was their elegant solution for making the fins undulate? Nine lever arms are attached to each fin. Those lever arms are controlled by two crankshafts which extend from the front of the body to the rear, one for each side. A servo motor then turns each crankshaft. Since the crankshafts are independent, that means each fin operates independently. This allows for turning by having one fin move faster than the other. A third motor in the head flexes the body, causing the robot to swim up or down.
There’s also a pressure sensor and an ultrasonic sensor in the head for depth control and avoiding objects and walls. While these allow it to swim autonomously in its acrylic, tubular track, there is wireless communication for recording sensor data. Watch it in the video below as it effortlessly swims around its track.
Three things that I love about participating in Maker Faires are seeing all the awesome stuff people have done over the past year, spending time with all my maker friends in one big room over two days and the reactions to what I made. The 2016 Ottawa Maker Faire had all this in spades.
There’s just something about BB-8 that touches people. I once heard of a study that showed that when buying kid’s toys, adults were attracted to circles, that that’s the reason teddy bears often have round heads with big round eyes. Similar reactions seem to happen with BB-8, the droid from last year’s Star Wars movie. Adults and kids alike pet him, talk baby-talk to him, and call to him with delight in their voice. I got those reactions all throughout the Maker Faire.
But my favorite reaction happened every time I removed the head and lifted the top hemisphere of the ball to expose the electronics inside. Without fail the reaction of adults was one of surprise. I don’t know if it was because of the complexity of the mechanism that was revealed or because it was just more than they expected. To those whom I thought would understand, I gave the same speech:
“This is the remote control receiver taken from a toy truck, which puts out negative and positive voltages for the different directions. That goes to this ugly hack of a board I came up with that converts it all to positive voltages for the Arduino. The Arduino then does pulse width modulation to these H-bridge driver boards, for speed control, which then talk to these two drill motors.”
Those I wasn’t sure would understand were given a simpler overview. Mine’s a hamster drive (we previously covered all the possible ways to drive a BB-8) and so I showed how it sits on two Rollerblade wheels inside the ball. I then flipped it over to show the heavy drill batteries underneath, and then explained how the magnets at the top of the drive mechanism attracted the magnets under the head, which got another look of revelation. All went away satisfied.
But BB-8 sometimes needs a break from human interaction and seeks out its own kind, like Bowie which you can read about below along with more awesome Maker Faire exhibits.
This is the kind of engineering that gets us excited, and not just because we like machines modeled on living things. Science Daily reports that Associate professor [Kristi Morgansen] from The University of Washington has developed these robofish for underwater data collection. Her technology is notable for two major reasons: the small robots use fins for locomotion instead of propellers, which reduces drag and creates greater maneuverability. The second and more important reason is that the robofish can communicate with each other via sonar, largely obviating the need for the robofish to surface for more instructions. Both design concepts were inspired by the shape and behavior of real fish. Currently the robots are only programmed to swim with or away from each other, but these are still prototypes and the technology looks promising. For more tech specs on these “Fin Actuated Autonomous Underwater Vehicles” (see why Robofish is better?), you can have a look at Morgansen’s notes.