Mapping The Depths With An Autonomous Solar Boat

July 23, 2023 by Tom Nardi 17 Comments

Ever look out at a pond, stream, or river, and wonder how deep it is? For large bodies of water that are considered navigable, it’s easy enough to pull up a chart and find out. But what if there’s no public data for the area you’re interested in?

Well, you could spend all day on a little boat taking depth readings and making your own chart, but if you’re anything like [Clay] you could build a solar-powered autonomous robot to do it for you. He’s been working on the boat, which he calls Gumption Trap, for the better part of a year now. If we had to guess, we’d say the experience of designing and building it has ended up being a bit more interesting to him than the actual depth of the water — but that’s fine by us.

The design of the boat is surprisingly economical, as far as marine designs go. Two capped four-inch PVC pipes are used as pontoons, and 3D printed brackets attach those to an aluminum extrusion frame that holds the electronics and solar panel high above the water. This arrangement provides an exceptionally stable platform that would be all but impossible to flip under normal circumstances.

Around the back of the craft, there’s a pair of massive 3D printed thrusters, complete with some remarkably chunky printed propellers. The lack of rudders keeps things simple, with differential thrust between the two motors enough to keep the Gumption pointed in the right direction.

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A wooden robot with a large fresnel lens in a sunny garden

Gardening Robot Uses Sunlight To Incinerate Weeds

June 30, 2023 by Robin Kearey 36 Comments

Removing weeds is a chore few gardeners enjoy, as it typically involves long sessions of kneeling in the dirt and digging around for anything you don’t remember planting. Herbicides also work, but spraying poison all over your garden comes with its own problems. Luckily, there’s now a third option: [NathanBuildsDIY] designed and built a robot to help him get rid of unwanted plants without getting his hands dirty.

Constructed mostly from scrap pieces of wood and riding on a pair of old bicycle wheels, the robot has a pretty low-tech look to it. But it is in fact a very advanced piece of engineering that uses multiple sensors and actuators while running on a sophisticated software platform. The heart of the system is a Raspberry Pi, which drives a pair of DC motors to move the whole system along [Nathan]’s garden while scanning the ground below through a camera.

The Pi runs the camera’s pictures through a TensorFlow Lite model that can identify weeds. [Nathan] built this model himself by taking hundreds of pictures of his garden and manually sorting them into categories like “soil”, “plant” and “weed”. Once a weed has been detected, the robot proceeds to destroy it by concentrating sunlight onto it through a large Fresnel lens. The lens is mounted in a frame that can be moved in three dimensions through a set of servos. A movable lens cover turns the incinerator beam on or off.

Sunlight is focused onto the weed through a simple but clever two-step procedure. First, the rough position of the lens relative to the sun is adjusted with the help of a sun tracker made from four light sensors arranged around a cross-shaped cardboard structure. Then, the shadow cast by the lens cover onto the ground is observed by the Pi’s camera and the lens is focused by adjusting its position in such a way that the image formed by four holes in the lens cover ends up right on top of the target.

Once the focus is correct, the lens cover is removed and the weed is burned to a crisp by the concentrated sunlight. It’s pretty neat to see how well this works, although [Nathan] recommends you keep an eye on the robot while it’s working and don’t let it near any flammable materials. He describes the build process in full detail in his video (embedded below), hopefully enabling other gardeners to make their own, improved weed burner robots. Agricultural engineers have long been working on automatic weed removal, often using similar machine vision systems with various extermination methods like lasers or flamethrowers.

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Get Your Leafy Meats

June 26, 2023 by Brian McEvoy 23 Comments

Some of us jokingly refer to our hobbies as “mad science,” but [Justin] from The Thought Emporium could be one Igor away from living up to the jibe. The latest project to come out of the YouTube channel, video also after the break, outlines a map for creating an artificial organism in their new lab. The purpose is to test how far a citizen scientist can push the boundary of bioengineering. The stated goal is to create a swimming entity with a skeleton. The Thought Emporium also has a neuron project in the works, hinting at a potential crossover.

The artifishal [sic] organism has themes at the micro and macro scale. [Justin] says, “Cells are like little nano-robots. Mainly in the sense that they just follow their built-in instructions to the best of their ability.” At the multi-cellular level, the goal is to program something to actuate muscle tissue rhythmically to sustain locomotion. The method for creating living parts is decellularization and recellularization, a technique we heard about at Hackaday Belgrade.

The Thought Emporium is improving upon its protocol which removes cells from their “scaffolding” to repopulate it with the desired type, muscle in this case. Cellular scaffolds retain the shape of whatever they were, so whatever grows on them determines what they become. Once the technique of turning a leaf into muscle fibers is mastered, the next step will be creating bones with a different cell line that will mineralize the scaffold. Optimizing the processes and combining the results may show the world what is possible with the dedication of citizen bioengineers.

Regenerative medicine is looking at replacement human-parts with similar techniques. We are eager to see fish that digest plastic.

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Cottonization: Making Hemp And Flax Fibers Into The Better Cotton

June 20, 2023 by Maya Posch 16 Comments

These days it’s hard to imagine that fabrics were ever made out of anything other than cotton or synthetic fibers, yet it wasn’t too long ago that hemp and flax-based fabrics — linen — were the rule rather than the exception. Cotton production has for centuries had the major disadvantages of requiring a lot of water and pesticides, and harvesting the cotton was very labor-intensive, making cotton rather expensive. In order to make separating the cotton fibers from the seed easier, improved versions of the cotton gin (‘cotton engine’) were developed, with the 19th century’s industrial revolution enabling a fully automated version.

What makes cotton attractive is the ease of processing these fibers, which are part of the seed pod. These fibers are 25 mm – 60 mm long, 12 μm – 45 μm fine fibers that can be pulled off the seeds and spun into yarn or whatever else is needed for the final product, much like wool. Hemp and flax fibers, in contrast, are extracted from the plant stem in the form of bast fibers. Rather than being pure cellulose, these fibers are mostly a mixture of cellulose, lignin, hemicellulose and pectin, which provide the plant with rigidity, but also makes these fibers coarse and stiff.

The main purpose of cottonization is to remove as much of these non-cellulosic components as possible, leaving mostly pure cellulose fibers that not only match the handleability of cotton fibers, but are also generally more durable. Yet cottonization used to be a long and tedious process, which made bast fiber-based textiles expensive. Fortunately, the steam explosion cottonization method that we’ll be looking at here may be one of the methods by which the market will be blown open for these green and durable fibers.

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Using Trash To Keep Plastic Trash Out Of Oceans By Kabooming Them

June 19, 2023 by Maya Posch 7 Comments

For a few years now, [Richard] of Tropical Ocean Cleanup fame has been working hard to clean the Philippines of the plastic trash that litters everything, and washes down the canals and rivers into the ocean. Using nothing but what is essentially trash – old car tires, rope and empty soda bottles – he creates ‘kabooms’ that prevent this trash floating in the canals from polluting the beaches, kill wildlife and gather in the oceans. In a recent video he covers how he creates these systems, and the basics of how they are installed.

We previously covered [Richard]’s efforts, and although these kabooms have received a few tweaks along the way, the basic principle has remained the same. The empty bottles provides the buoyancy, while the tires are excellent structural elements that can take a beating from the weather and debris. Some of the kabooms are lashed together with rope, while for other types holes are drilled into the tires using a hole saw, all of which help to create a self-supporting trash capture system that can be installed easily with a group of volunteers.

Fetching the thus captured trash is still a bit of a struggle, requiring a fair bit of manual labor, nets and boats from local fishermen when they have some spare time, but the effect is very much noticeable on the nearby beaches. In addition to these trash capturing kabooms, [Richard] also promotes trash collecting at schools, organizes trash pick-up events and trash collecting points, to raise local awareness of the need to keep plastic trash out of the environment and burn pits.

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Tree Planting Festivals, Air Cannons, Self-Burying Seeds, And The Complexities Of Reforestation

June 8, 2023 by Maya Posch 20 Comments

At first glance the problem of how to plant trees would seem to be a straightforward one: take a seed, jam it into the soil and let nature take its course. Or alternatively do much the same with a sapling that already got a start in a nice, comfortable greenhouse before leaving it to its own devices. To the average person this is generally the point where it’s considered a ‘done deal’, but one only has to take a look at the average survival rate of saplings out in the wild to perish that thought.

Each environment offers its own set of challenges when it comes to reforestation, which can perhaps be considered ironic as many of these trees are being planted where forests used to be, albeit centuries ago in many cases. There are the easy spots, such as flat fields, with rich soil, ample rain and mild weather, to the challenging terrain of Iceland, or mountainous terrain. Here the logistics are challenging and where once rich forests flourished, the very landscape seems adamant to reject this botanic intrusion.

Further complicating matters here are the myriad of reasons why we’re looking at planting so many new trees that it has even become an internet thing, as with the 2019 ‘Team Trees’ 20 million new trees challenge. So how did we get here, why exactly are we doing all of this, and how much of these attempts do bear fruit?

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A Fresnel Lens Without The Pain

June 3, 2023 by Jenny List 21 Comments

Making a traditional glass lens requires a lot of experience, skill, and patience grinding a piece of glass to the required shape, and is not for the casual experimenter. Making a glass Fresnel lens with its concentric rings requires even more work, but as the ever-resourceful [Robert Murray-Smith] shows us, a Fresnel lens can be made from far more mundane materials. He shows us a working lens made from transparent plastic tube, and even successfully smoulders a piece of paper with it under the anaemic British sun.

His lens, with its circular profile tube filled with water, is not perhaps the most efficient lens in terms of light focused per unit area of lens. From dredging up our highschool physics lessons we are guessing that half the light is diffracted outwards rather than inwards by the cylindrical profile of the coil, but for the cost of the whole device we’re not sure that matters. Next time we’re shipwrecked on a desolate island with a handy supply of clear plastic tube and fresh water, we know we can always raise a fire.

If Fresnel lenses interest you, we’ve taken a look in the past at their history.

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