Swimming Pool Lap Counter Relies On Ultrasound

Swimming is a great way to exercise, both for the cardiovascular benefits and the improved muscle tone. However, while he’s a fan, [Peter Quinn] sometimes finds it hard to keep track of how far he’s gone when he gets in the zone. Obviously, the solution is an electronic lap counter, which [Peter] promptly set about creating.

The build is based around an ultrasonic distance sensor, which is triggered when it detects a swimmer approaching the end of the lane. It’s run by an Arduino Nano, which is also set up to announce the accumulated distance with a speech synth library. [Peter] notes there have been some stumbling blocks thus far, necessitating modifications along the way. Water ingress into the ultrasonic sensor has required the installation of a protective shroud, while battery operation has required a module to properly handle the lithium-polymer battery.

While we might hesitate to bring a takeaway container full of wires, circuit boards and an LED display to a public pool for fear of being deemed a bomber, the basic bones of the project are a great way to approach the problem. There’s plenty of scope to implement laptiming too, as we’ve seen in other sporting builds!

Diving With An Unlimited Air Supply

If you want to explore underwater, you have a few options. You can hold your breath. You can try to recycle your air. You can carry your breathing air with you as in SCUBA. You can stick a tube up like a snorkel, or you can have air sent down to you from the surface. EXOlung falls into this last category, but unlike many other surface solutions, it has a twist: it never runs out of power before you do. Watch the video below and you’ll see how it works.

A buoy puts a snorkel up out of the water, and a tube lets you dive up to 5 meters away. There’s a small tank on your chest, and your body’s motion serves to fill the tank from the outside air supply. As your legs extend and retract, you fill the tank and then put the tank’s air at ambient pressure so you can breathe. As a bonus, by varying how you inhale and exhale, you can control your buoyancy and, therefore, your depth.

The system does require you to strap your legs up to the apparatus. However, other similar systems have compressors or batteries which can fail or run down, meaning there can be a limit on how long you can stay under. EXOlung claims there is no limit to how long you can stay under.

The cost looks to be around 300 Euro, although for a bit more you can get one that uses different materials to withstand higher pressures. That one has a 7-meter hose.

Another approach is to just carry a little air and remove the CO2 from it and rebreathe it. We’ve also seen a risky surface air pump that uses wind power.

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This Heads Up Display Is All Wet

Athletes have a long history of using whatever they can find to enhance their performance or improve their training. While fitness tracker watches are nothing new, swimmers have used them to track their split times, distance, and other parameters. The problem with fitness trackers though is that you have to look at a watch. FORM has swim goggles that promise to address this, their smart goggles present the swimmer with a heads-up display of metrics. You can see a slick video about them below.

The screen is only on one eye, although you can switch it from left to right. The device has an inertial navigation system and is — of course — waterproof. It supposedly can withstand depths up to 32 feet and lasts 16 hours on a charge. It can use Bluetooth to send your data to your phone in addition to the display.

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[Festo’s] Underwater Robot Uses Body-Length Fins

[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.

The BionicFinWave's fin mechanismWhat 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.

[Festo] has created a lot of these marvels over the years. We’ve previously covered their bionic hopping kangaroo (we kid you not), their robot ants with circuitry printed on their exoskeleton, and perhaps the most realistic flapping robotic bird ever made.

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Rolling Robot With Two Motors, But None Are On The Wheels

This unusual 3D printed Rolling Robot by [ebaera] uses two tiny hobby servos for locomotion in an unexpected way. The motors drive the front wheel only indirectly, by moving two articulated arms in a reach-and-retract motion similar to a breaststroke. The arms are joined together at the front, where a ratcheting wheel rests underneath. When the arms extend, the wheel rolls forward freely. When the arms retract, the wheel’s ratchet locks and the rest of the body is pulled forward. It looks as though extending one arm more than the other provides for rudimentary steering.

The parts are all 3D printed but some of them look as though they might be a challenge to print well due to the number of small pieces and overhangs. A short video (embedded below) demonstrates how it all works together; the action starts about 25 seconds in.

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Soft Robot With Microfluidic Logic Circuit

Perhaps our future overlords won’t be made up of electrical circuits after all but will instead be soft-bodied like ourselves. However, their design will have its origins in electrical analogues, as with the Octobot.

The Octobot is the brainchild a team of Harvard University researchers who recently published an article about it in Nature. Its body is modeled on the octopus and is composed of all soft body parts that were made using a combination of 3D printing, molding and soft lithography. Two sets of arms on either side of the Octobot move, taking turns under the control of a soft oscillator circuit. You can see it in action in the video below.

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Tissue-Engineered Soft Robot Swims Like A Stingray

We’re about to enter a new age in robotics. Forget the servos, the microcontrollers, the H-bridges and the steppers. Start thinking in terms of optogenetically engineered myocytes, microfabricated gold endoskeletons, and hydrodynamically optimized elastomeric skins, because all of these have now come together in a tissue-engineered swimming robotic stingray that pushes the boundary between machine and life.

In a paper in Science, [Kevin Kit Parker] and his team at the fantastically named Wyss Institute for Biologically Inspired Engineering describe the achievement. It turns out that the batoid fishes like skates and rays have a pretty good handle on how to propel themselves in water with minimal musculoskeletal and neurological requirements, and so they’re great model organisms for a tissue engineered robot.

The body is a laminate of silicone rubber and a collection of 200,000 rat heart muscle cells. The cardiomyocytes provide the contractile force, and the pattern in which they are applied to the 1/2″ (1.25cm) body allows for the familiar undulating motion of a stingray’s wings. A gold endoskeleton with enough stiffness to act as a spring is used to counter the contraction of the muscle fibers and reset the system for another wave. Very clever stuff, but perhaps the coolest bit is that the muscle cells are genetically engineered to be photosensitive, making the robofish controllable with pulses of light. Check out the video below to see the robot swimming through an obstacle course.

This is obviously far from a finished product, but the possibilities are limitless with this level of engineering, especially with a system that draws energy from its environment like this one does. Just think about what could be accomplished if a microcontroller could be included in that gold skeleton.

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