Automatic fish feeder

This automatic fish feeder didn’t take long to put together and it allows you to adjust how much food is dispensed. [Gagandeep Singh] built it around an Atmel AT89C2051 microcontroller. Like many of the automated feeding systems we see, this uses a character display and a few buttons for the user interface. We’re always curious at how they mechanically dispense the food. In this case, the motor seen at the left pulls open a sliding baffle which is pulled closed again by rubber bands at the right. It’s a bit more involved than the last fish feeder we saw, but your guess is as good as ours on which system works better.

Hacker finds better use for a Windows machine

[Patrick Becker] had an ancient PC on his hands with a blown PSU. He converted this into a stylish home for his Betta splendens.

The aquarium itself is fashioned from a piece for construction glass block with the top cut off. This allows for a window that looks through the tank and shows off the motherboard on the other side. He patched into the AC connector so that the original power cord can be used to control the pump. A lighted pump button was added to the front panel and a fancy bezel fitted to the viewing portal in the side of the case. He finished off the project with a PVC pipe for air and food. His blue screen of death now features water and a real fish.

Polycarbonate fish uses three servos to swim


[Amnon] is learning the hard way that water and electronics don’t always like to play nicely together. He’s been working on creating a swimming fish that uses three servos to flex a sheet of fish-shaped polycarbonate. This photo doesn’t really do the project justice but you can get a better idea of what he’s accomplished by watching the videos after the break.

The three servos along with some distance sensors for obstacle avoidance are all controlled by a PIC 16F877A microcontroller. [Amnon] tried out three different waterproofing methods; coating the device in varnish, dipping it in hot glue, and dipping it in epoxy. The first two resulted in water damage to the electronics, but the third managed to work. It kept the water out, but also prevents reprogramming of the controller.

Although not successful, we would have loved to see the process of dipping the fish in a churning vat of molten glue. Once perfected, this may be the perfect platform for carrying our weapons of doom.

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Robot fish CAD models

[Bre] dug up this excellent robot fish prototype project. The PPF-O9 has three servos. One on the forward fins to control depth, one on the middle joint, and one final one drives the tail fin. The battery box is mounted to the underside. The control scheme is interesting: the right stick controls left/right and up/down while the left stick controls the frequency and amplitude of the motion. They say the robot is fairly stable, but swimming and turning can be slow. They’ve included CAD files for almost every component to help you with your own designs.

In June, we highlighted a robofish designed for swarm communication.

Robot red snapper

Engineers at the University of Kitakyushu have built this red snapper robot. Intended for wildlife surveys, this robot sports an array of sensors as well as a hand painted silicon body. It is decidedly more realistic looking than the Robofish and the Essex University robot fish. They say that the life like construction will aid in getting information about natural behavior of sea animals since it won’t stand out. It features a “unique” propulsion system that allows it to swim like a real fish. More information on that system would be nice. You can see more pictures of it here, but the descriptions are all in Japanese.

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Robofish > real fish

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.