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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Smoke Some Weeds: Lasers Could Make Herbicide Obsolete

April 26, 2023 by Lewin Day 53 Comments

We’ve all tangled with unwelcome plant life at one point or another. Whether crabgrass infested your lawn, or you were put on weeding duty in your grandfather’s rose patch, you’ll know they’re a pain to remove, and a pain to prevent. For farmers, just imagine the same problem, but scaled up to cover thousands of acres.

Dealing with weeds typically involves harsh chemicals or excessive manual labor. Lasers could prove to be a new tool in the fight against this scourge, however, as covered by the BBC.

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Solar Powered Weeding Tractor Uses Manual Labour

October 15, 2019 by Danie Conradie 2 Comments

You might not have realised this, but there’s a group of hackers out there without whom you wouldn’t be able to put food on the table. They hack under the blazing sun and pouring rain, and have been doing it for thousands of years. Known more commonly as farmers, their creative problem solving skills with whatever is lying around can be absolutely jaw dropping. [Andrew Mans] is one such individual. He built a solar powered weeding tractor that uses human labour to do the actual weeding.

We’ll be honest, this made us go “Wait, what?” for a few seconds, until the ingenuity of it all sank in. Crawling at a snails pace across the onion fields at Mans Organics, the contraption allows 3 workers to lie comfortably on their stomachs in a shaded tent, while pulling weeds that grow too close to the crop for conventional mechanised weeding methods. While this might seem like a slightly crappy job at first glance, there are definitely worse jobs a farm (or in an office) and actually looks quite relaxing. While the picking could of course be automated, this is no small task, especially when your business is food production, not robotics.

Power is provided from four 250 W solar panels on the roof, which charge a bank of deep cycle batteries and the drive train. A pure sine wave converter provides power to a 240 V motor driver which turns it back into DC to run the drive motor. [Andrew] admits this back and forth voltage conversion is overcomplicated and inefficient but it’s the sort of thing that quickly happens when you hack a hacked design. The axle and 5-speed gearbox was salvaged from an old 3 ton truck and is mounted vertically to save space. The hydraulic steering is controlled by one of the human weed pickers, who just makes small course corrections as required.

We love the weird combo of old and new in this hack. Check out the machine in action and detailed walk-around after the break. Continue reading “Solar Powered Weeding Tractor Uses Manual Labour” →

The Weedinator Returns

March 24, 2018 by Donald Papp 42 Comments

We are delighted to see The Weedinator as an entry for the 2018 Hackaday Prize! Innovations in agriculture are great opportunities to build something to improve our world. [TegwynTwmffat]’s Weedinator is an autonomous, electric platform aimed at small farms to take care of cultivating, tilling, and weeding seedbeds. The cost of this kind of labor can push smaller farms out of sustainability if it has to be done by people.

Greater efficiency in agriculture is traditionally all about multiplying the work a single person can do, and usually takes the form or bigger and heavier equipment that can do more at once and in less time. But with an autonomous robotic platform, the robot doesn’t get tired or bored so it doesn’t matter if the smaller platform needs to make multiple passes to cover a field or accomplish a task. In fact, smaller often means more maneuverable, more manageable, and more energy-efficient when it comes to a small farm.

The Original Weedinator was a contender for the 2017 Hackaday Prize and we’re deeply excited to see it return with an updated design and new people joining their team for 2018. Remember, there’s money set aside to help bootstrap promising concepts and all you really need to get started is an idea, an image, and documentation. There’s no better opportunity to dust off that idea and see if it has legs.

Robot Lives In Your Garden And Eats The Weeds

May 18, 2017 by Dan Maloney 50 Comments

You can’t deny the appeal of gardening. Whether it’s a productive patch of vegetables or a flower bed to delight the senses, the effort put into gardening is amply rewarded. Nobody seems to like the weeding, though — well, almost nobody; I find it quite relaxing. But if you’re not willing to get down and dirty with the weeds, you might consider deploying a weed-eating garden robot to do the job for you.

Dubbed the Tertill, and still very much a prototype, the garden robot is the brainchild of some former iRobot employees. That’s a pretty solid pedigree, and you can see the Roomba-esque navigation scheme in action — when it bumps into something it turns away, eventually covering the whole garden. Weed discrimination is dead simple: short plants bad, tall plants good. Seedlings are protected by a collar until they’re big enough not to get zapped by the solar-powered robot’s line trimmer.

It’s a pretty good idea, but the devil will be in the details. Will it be able to tend the understory of gardens where weeds tend to gather as the plants get taller? Can it handle steep-sided raised beds or deeply mulched gardens? Perhaps there are lessons to be learned from this Australian weed-bot.

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