Targeted laser kills weeds, thins crops

Chemical-free approach from Carbon Robotics uses artificial intelligence for highly precise work in specialty crops.

When Carbon Robotics started up four years ago, the focus was on development of vision systems and weed identification, with an eye toward precise control. The differentiator for this startup, however, wasn’t a more precise spraying system, it was the use of lasers. In effect, the company has designed an implement — the LaserWeeder — that identifies weeds on the go and kills them with a beam. And now it’s adding a new capability to its system.

“The laser was the result of trying everything we could find to figure out the most effective solution,” says Paul Mikesell, founder and CEO of Carbon Robotics. “When we realized we could make the laser work, we spent a lot of time proving it out.”

He notes that the precision required for using lasers to control weeds is much higher than using a spray nozzle. “To get the kind of accuracy and granularity to be able to put a laser at the right spot of the plant is more difficult than probably any other tools you’ve seen,” Mikesell notes. “We have to hit the right spot of the meristem of the weeds in order to kill it efficiently.”

That means hitting that weed on the go in the right spot with 20 joules of energy. The company is using precise image capture combined with an advanced artificial intelligence system to get the job done. While farmers raising a high-value specialty crop may not care about the AI involved, they are interested in a chemical-free approach to stopping weeds.

The company has slated deliveries of machines to farms in 17 states and three provinces in Canada for 2023. And Mikesell says interest is growing.

New service adds capabilities

Just ahead of World Ag Expo, Carbon Robotics announced it was adding a component to its machine — LaserThinning. The LaserWeeder can now be used to target areas of vegetable crops that are purposefully overseeded and then thinned for optimal crop spacing, growth and yield. Thinning is a common practice for direct-seeded crops, including leafy green and cole crops such as lettuces and broccoli.

This raises the precision level of the system because it not only identifies weeds, but also analyzes a crop planting pattern to thin a crop with precision. This is a role currently carried out by chemical thinning systems, but Mikesell says the LaserWeeder eliminates risks created by those conventional systems.

He says the computer vision system can distinguish when there is only one crop when it might appear as two. “For instance, if I am a grower and I am bumping along down the field, I may have a prediction about where all the weeds are. If I accidentally think there are two weeds when there’s really only one, I could make a huge mistake and accidentally thin a crop that’s needed. That’s what the precision system helps to avoid.”

The LaserWeeder can be set to weeding mode, thinning mode, or weeding and thinning mode using its iPad interface.

This is precision application at a new level — identifying the crops and determining which must be taken out for the best planting pattern for top performance. Mikesell says the system’s neural network can be trained for each crop in as little as 24 to 48 hours, allowing Carbon Robotics to meet a farmer’s precision thinning needs.

Training a system often requires exposing the computer to thousands of images so the system knows what to target. Mikesell says the key is having the right imagery.

“It’s easy to make a mistake, and say I’ll gather 10,000 images,” he says. “But to be efficient in this deep learning training pipeline, you need to know what are the most important 2,000 images out of that set that I’ve gathered.”

Being more focused on knowing the right images to use, such as time of day, how the crop looks when its windy, or even a change in soil type, can boost precision for thinning and weed management. It’s that precision approach within a precision system that offers efficiency.

Power at work

Turning lasers on weeds sounds like science fiction, but it’s reality for Carbon Robotics. It’s a chemical-free approach to weed control, and now crop thinning, which is gaining popularity in the specialty crop business. Mikesell says the day may come when this machine rolls into row-crop country, but that’s in the future. For now, the high-value specialty crops around the country are the main opportunity. And in 2023, he’s planning on showing the machine beyond the West to growers in the East as well.

Electricity for the laser system comes from a PTO generator on the LaserWeeder. Mikesell says the system requires about 60 kilowatts of power and can be run by a 110-hp tractor, or larger. There is also an automated version the company uses as a demonstration machine, but for now, a pull-type unit is the focus for the market. “There are other issues we have to work out before we can use the autonomous machine commercially,” he notes.

Mikesell adds that a tractor manufacturer that can offer a 240-volt plug would be a step up for the LaserWeeder, eliminating the need for that PTO generator and simplifying the system.

You can learn more about the system and see it in action at carbonrobotics.com. The company is also taking the unit to a range of shows this year to demonstrate it in action.