Agricultural robots are growing in popularity – but can they be made more affordable? That's the aim of Robotriks, a company that has created an autonomous platform which can be built at low cost and, within a few hours, be ready to get to work.

“The aim is to create a system which is affordable and reliable,” said director Jake Shaw-Sutton. The Robotriks Traction Unit (RTU) costs just £7000 – almost a tenth of the cost of most others on the market.

One of the main challenges the RTU addresses is lack of manual labour on farms. “It’s not about taking away jobs, it’s about filling jobs where there currently are no people available to do them,” said Mr Shaw-Sutton, who is also a senior robotics technician at the University of Plymouth. “For a while there have been fewer people willing to go out into the fields and harvest fruit and vegetables; this is an autonomous solution to that.

“Even with the current cost of the unit, which we’re always trying to improve, it still works out cheaper than having someone employed on minimum wage – it can work for more hours, not needing lunch breaks or to sleep at night.”

Mr Shaw-Sutton and his co-founder Khaian Marsh both grew up on farms, so the RTU has been put through its paces in real life situations, including testing for soil compaction. “There’s a small module with sensors which bolts onto the side of the RTU; when it is pushed into the soil it can measure the force needed as well as moisture, and because it is on the RTU the data is processed there and then,” he explained.

The unit comprises a large drive wheel, suspension and a computer system, held together by galvanised pipe – on which farmers can attach pretty much any implement. This includes conventional items such as a tow hitch, wheelbarrow or grass cutter, but also more high-tech and new devices including soil probes, robotic harvesting arms or depth cameras for 3D crop rendering.

The component parts are all mass produced rather than specialist, which brings the costs down – for example the wheel’s brushless hub motor is from an electric bike. “The unit is fully adjustable to any height and width; some farms may have narrow paths, for example in fruit and vegetables, or it might need to go wider to get over tall crops,” he explained.

The RTU works either by remote control or autonomously. “We’re trying to make it as simple as possible. We currently have three options; the first uses a remote control to drive the unit to a location, mark it as a point, drive to the next position and mark another point – then it will keep driving between those points.

“The second uses an online map, which appears on a display with the current location. The operator can click where they want to send the unit and it will go there.”

The third, which is still under development, features full autonomous control. “It is managed by drones. The positioning system on board the RTU is known as Real Time Kinematic (RTK) and allows for centimetre level precision from satellites. It is also the same system used by DJI Drones - the camera on board then gives a bird’s eye view, and their coordinate frames can be easily matched,” explained Mr Shaw-Sutton.

“The drone’s vision works on multispectral colour which features visible and infrared light, for example it may see the field as green and a patch of weeds as yellow – it can then send a coordinate to the RTU and instruct it over to spray off the patch of weeds.”

Although the RTU is still in the testing phase, it is being offered commercially to researchers and they hope it will have enough functionality to offer to a wider market over the next year.