Hot Dog!

Keeping a typical lawn free from weeds is a big enough chore, but when weeds are infesting agricultural land the problem is exponentially worse. In these cases the issue is not merely that weeds are unsightly, but rather that they compete with crops for resources like nutrients, water, and sunlight. So as weeds run rampant, which they are sure to do without intervention, crop yields decrease and farmers put more and more money into water and nutrients that are soaked up by the weeds.

Traditional weed control approaches involve either the widespread application of herbicides or manual removal. Many herbicides are quite effective and have greatly increased crop yields, however, they can also be responsible for negative environmental impacts. Manual removal is extremely labor-intensive. For larger farming operations, plucking weeds quickly becomes prohibitively expensive and time-consuming.

Modern technological advances are opening the door to a third option — robotic weed control. This is still a nascent field, so the best path forward has not been worked out yet, but a great deal of experimentation is in progress. A team led by researchers at Texas A&M University has proposed a solution that will get anyone that is fed up with weeds pumping their fists in the air with excitement. They have developed a robot dog equipped with a flamethrower that has been programmed to seek and destroy any undesirable plant life.

This may sound like an extreme approach at first blush, but in reality it could prove to be a very practical solution to our present problems. The flamethrower can precisely target individual plants without the need for herbicides or any other chemicals to be released into the environment. Furthermore, a group of these robots could continually scan a piece of land autonomously, eliminating the effort associated with manual weeding.

The system was built around a Boston Dynamics Spot Mini robot dog. Additionally, a 6-DoF Unitree Z1 manipulator/arm was mounted on the robot’s back. At the end of the arm, the researchers attached an Intel Realsense D435 RGB-D depth camera for use in weed detection and localization. Further, a pair of FLIR Lepton 3.5 thermal cameras were included to monitor the flame and its coverage area. Speaking of the flame, a propane tank was mounted on the robot so that it could feed into a torch at the end of the arm. All processing was handled by Spot’s on-board computer.

When the robot’s computer vision algorithm detects a weed, it blasts it with the flamethrower. It does not seek to incinerate the weed, however, and instead just gets it a bit toasty. Ideally the plant would be completely destroyed, but it was found that it took too much propane to make this happen, which would leave the robot needing constant tank refills. The blast of heat was shown to be sufficient to stun weeds and keep them from growing for several weeks, so it does seem like a reasonable compromise.

Initial field testing demonstrated that the robot is effective at stunning weeds, and can do so with a high level of precision. It was noted, however, that Spot can only run for about 40 minutes before needing a recharge. This could severely limit its ability to keep a large area clear of weeds.

Looking ahead, the team intends to continue refining their system. They plan to, for example, update the software so that the flamethrower can stun multiple weeds at a time. They also plan to experiment with other novel weed removal techniques, like electrocution.