Harnessing satellite navigation to cut grass

Published: 
10 February 2010

BigMow, an autonomous mower, moved across a football pitch located at Toulouse, France, stopping neatly at its edge, then turned around to complete a manoeuvre. It then neatly wove through a line of obstacles, demonstrating its ability to navigate close to centimetre precision.

Normally, BigMow uses sensors and wires embedded in a field to cut a lawn automatically. But for the demonstration conducted at Toulouse’s stadium on 7 October 2009, the specially-adapted robot navigated wholly by satellite signals – and used software developed by Mow by Sat, a project co-financed by the EU’s Seventh Framework Programme for Research and Technological Development (FP7).

Left to right: François Briançon, representative of Toulouse’s regional government; Yves Lantonnois; Michèle Poncelet; Donato Melita © Ahmed ElAminLeft to right: François Briançon, representative of Toulouse’s regional government; Yves Lantonnois; Michèle Poncelet; Donato Melita © Ahmed ElAmin

FP7 funding for projects like Mow by Sat aims to promote the use of Europe’s EGNOS, the EGNOS Data Access System (EDAS), and later, Galileo for commercial applications. In particular, by adapting automated machines already used in the marketplace, Mow by Sat aims to show how satellite navigation can be used to achieve greater precision and lower costs.

Increased safety

The project partners are Nav on Time, Belrobotics and the University of Catania. Michèle Poncelet, the project’s coordinator and general manager of Nav on Time, says the technique used for the demonstration can be used to adapt automated machines already used for precision farming, for example. With greater precision comes increased safety in the use of robots and automated machines could appear for other applications such as those used for logistic and emergency rescue operations, she says.

Nav on Time, a France-based start up, developed the satellite navigation software and the technique of using the more accurate carrier phase of the GPS signal, known as GPS Real Time Kinematic (RTK). The company wants to licence its technology to a variety of market sectors once it is fully developed. The demonstration in Toulouse was the first of two the project has scheduled. The second will be conducted in Belgium next year.

Belrobotics supplied one of its commercial BigMow automated lawnmowers, which are mainly purchased for golf courses and large private estates. The Belgium-based company modified the guidance laws for BigMow to take advantage of the benefits of the satellite navigation technology.

Belrobotics was targeted as automated lawnmowers are one of the fastest growth segments in the robotics sector. Yves Lantonnois, the company’s chief executive, says Belrobotics will soon integrate the Nav on Time software in a commercial model of its BigMow machine.

Eliminating traditional limitations

This use of satellite navigation will make Belrobotics’ machines more competitive in the growing marketplace as clients will not have to spend money on burying tracking wires in the ground, he says. In addition to the savings, the technology will allow users to programme the lawnmower to move in a systematic pattern and make changes to the track when necessary from a remote computer. Currently, automated lawnmowers using buried wires are confined to moving in random patterns.

“Satellite navigation eliminates the traditional limitations of robot lawnmowers and offers the full benefit of our state of the art technology,” says Lantonnois.

Meanwhile researchers at the University of Catania in Italy are simulating the use of the Nav on Time software with GPS, Galileo, GPS plus Galileo RTK and EGNOS as a means of comparing the levels of accuracy and the availability of integrity that can be achieved.

The team is examining the use of EGNOS and its related real-time commercial data service, EDAS, for the Nav on Time application. EGNOS, EDAS and Galileo compatibility will ultimately be incorporated in the software and hardware.

The researchers have developed the simulation tools needed to demonstrate the benefits EGNOS and Galileo will bring to robotic applications and in particular to the Mow by Sat system, says University of Catania researcher Donato Melita.

So far, simulations show that the Now on Time system improves on the accuracy of GPS significantly, he says. The results of the simulations using EGNOS and Galileo for similar applications will be ready by the end of this year.

Once the results have been achieved a live demonstration using EGNOS and EDAS for mowing the lawn will be undertaken as part of the project. EDAS is useful in situations where the EGNOS signal may be blocked, such as in urban canyons or under trees, he says.

“We are demonstrating that the Nav on Time system and EGNOS improve on the accuracy of GPS,” he says.

Lowering costs with EGNOS and EDAS

For the demonstration in Toulouse Nav on Time adapted two commercial GPS receivers to work with its software and hardware. One is embedded in the roving robot while the other is placed in a fixed position at the edge of the football pitch.

The technique used GPS RTK to achieve centimetre precision. The lawnmower was then programmed to move in a set pattern from a computer. The connection was made via a wireless local area network.

The use of GPS RTK is generally too expensive for such applications as mowing lawns. Once the technique is adapted to use EGNOS and EDAS, Nav on Time hopes to bring the cost down to acceptable levels, says Poncelet.

“This demonstration is an illustration of our vision of using satellite navigation for more extended robotics applications,” she says. “Our system can take into account local events that interfere with accuracy of the satellite navigation signal and corrects for them.”

Once Nav on Time is able to complete the development of its technology for the Belrobotics lawnmower, it will then target the precision agriculture sector, especially for guided tractor applications, Poncelet says.

Nav on Time also plans to develop applications where the technology can be integrated into robots that use optical sensors for guidance. Such integration will provide robots with the flexibility to be used both outdoors and indoors, where navigation by satellite may be less accurate or impossible.

For now, the partners are pleased they were able to show how BigMow could operate just by satellite navigation, a first step on the way to establishing a viable business in the EGNOS and Galileo marketplace.

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More information:

EGNOS
EDAS
Mow by Sat

Updated: Sep 01, 2014