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What makes igus® parts ideal in an agricultural weeding robot?

The world’s first non-chemical weeding robot for cereal crops, made by agri-tech start up Small Robot Company, has successfully identified and killed weeds at a field trial in Hampshire. The wheeled robot uses igus® delta robot arms to position a “zapper” and deploy ‘lightning strikes’ to kill weeds. Delta robot arms from igus® were selected for their precision, low-cost and lubrication-free engineering. The weed killing robot, called “Dick”, works in concert with a monitoring robot, “Tom”. Tom identifies weed patches then kills individual plants with a zapper device.

Working together

Small Robot Company with key partners igus and RootWave have demonstrated the world’s-first self-driving robot that can identify and kill weeds with a specialised “zapper” device using electricity.

It is the world’s first non-chemical robotic weeding robot that can destroy weeds at an individual plant level. This makes it an exciting, low impact technology for farming where the currently necessary blanket spraying of herbicides involves costly wastage. It also has a detrimental impact on the environment.  In addition, soil degradation from herbicides and soil compaction reduces crop yields.

The weed killing wheeled robot, called “Dick”, fitted with igus’s delta robot arms, successfully identified individual weeds using artificial intelligence (AI) and vision technology. The zapper end effector is supplied by RootWave. Small Robot Company (SRC) has developed three robot variants for farming applications – Tom, Dick and Harry.

Leading motion plastics company igus’s delta robot, used commonly in industry for pick-and-place operations, manoeuvres the zapper into place using an integrated motor and encoder. This is then linked to the Dick robot’s master controller. The three igus® delta arms fitted to each Dick can destroy weeds simultaneously.

Why were igus® products chosen for the weeding robot?

igus® was selected as the preferred delta robot manufacturer due to the light weight, precision and low cost element. Many competing delta robots cost up to £20,000 while the igus delta is about £5,000. It was developed at this price as part of igus’ Low-Cost Automation division for R&D applications.

Also at the event, the “Tom” monitoring robot uses proprietary Wilma artificial intelligence (AI) to scan the field for weed patches which it uses to define a path for “Dick” to follow. Dick is then dispatched. The Dick robot can now both identity specific weeds in a patch and kill them.

This two-robot approach demonstrates SRC’s “end-to-end service” model. This model uses multiple robots with AI working together to scan the field on a plant level then take action. Furthermore, SRC and igus® are looking to work on different actions. For example, where Tom and Dick could combine again for spot spraying, spot fertilizing or slug killing.

The igus® delta robot’s components and control system is key to the weeding robot’ killing operation. The ease of use and cost are paramount. The delta units are made from standard drylin® parts. This makes assembly easy and low cost.

Read more about robot and automation here.

Who controls the weeding robots?

Stepper motors are linked to controllers in the weeding robots. This helps position the delta robot directly over the weeds. The motors have encoders. This helps the delta know what position it is in, with good industrial protocols so they are easy to programme. The SRC’s robot’s, i.e. Dick’s, master controller and AI “speak” to the igus® motor controller to synchronise the robot’s position with the delta arm. This forms a closed loop monitoring system.

igus® Low-Cost automation engineer Angelos Bitivelias has worked with universities and industrial companies on delta robots. He brings the knowledge of how the igus® delta can be best modified for the weed killing application.

“The Dick robot moves to one side, a camera takes a photo of the weed, the AI identifies it as a weed. Then AI decides where to zap it,” says Angelos. “The kinematics of the delta makes it well suited to the end effector. The belt drive means the zapper is always parallel to the ground below.”

Lubrication-free weeding robot

An essential feature of the delta and igus® components is they are lubrication-free. Lubricated moving parts would potentially clog up with soil and water in a muddy field. However, this is not the case with the igus® dry running polymers.

Precision is also a strong feature. “The milestone we’ve hit is that we can now take action at the plant level,” says Andy Hall, head of prototyping, Small Robot Company. “Using artificial intelligence, the robots can recognize the weeds in the [camera] shot and target the robotic arm onto those weeds. At that point we can do anything we want. Our robotic platform incorporating the igus® arm could have many different technologies bolted on.”  

The affordability, precision, durability and reliability of the igus® delta robots are perfect for this and new agricultural applications, says Managing Director of igus® UK, Matthew Aldridge. “Because the delta is lightweight and low-cost it has opened up new opportunities for these robots to be used in mobile applications. This has proved a new technology in a harsh outdoor environment. Igus® is planning to work with SRC on new industrial applications”.

What’s next?

“To prove the power of per plant farming, we are focused on answering the biggest problem that farmers face at the moment, which is weeding,” comments Ben Scott-Robinson, CEO and co-founder, Small Robot Company. “We’ve now proved we can deliver per plant weeding: a world first. The focus for us now is being able to move forward to deliver this repeatedly, and at scale. This will be game-changing.”

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