A whistle sounds in the stadium. The players run on. Bright floodlights illuminate every angle of the space. And the audience can see a perfectly mowed lawn. Admittedly, most visitors are probably more excited about watching a great soccer match – the lawn has become part of the background. It lays the foundation for an exciting sporting event. And there is a lot of intense work involved in making the greenery look so good. On a soccer field of up to 8,250 square meters, there is a lot of grass to maintain. There is even more to do on golf courses.
So it is good to have a strong helper like the CEORA robotic mower from Swedish manufacturer Husqvarna. Depending on the cutting quality, the professional turf care device can mow up to 50,000 square meters in a period of two days. And it does all of this on its own, quietly and without emissions. This not only alleviates the soccer stadium’s groundskeeper but also makes for easier work on golf courses. And it is a reliable partner for taking care of public green spaces. How does it do it? Using components that developers have specially designed for these Herculean tasks.
The one for big spaces
Bilader Younadam is an electro-mechanical motor design engineer at Husqvarna and is responsible for the CEORA project. He explains, “The robotic mower has a modular design. It consists of a drive unit and a front unit with a cutting deck. Here, a total of 15 high-speed steel blades are mounted across three blade discs. They ensure efficient and precise cuts.” If maintenance or cleaning is required, the cutting deck can simply be tilted into an ergonomic position and worked on comfortably. The drive unit is available in two versions with varying cutting powers. Younadam says: “Professional users require high performance from our devices. At CEORA, we have increased the capacity by ten times compared to our other robotic mowers.”
The powerful helper moves over green spaces at one meter per second. Two impellers propel it on its long journeys. To keep doing this reliably, Husqvarna relies on motors from ebm-papst. “When selecting the components, we look for high quality levels, good performance and the right price-performance ratio,” says Younadam. EC external rotor motors from ebm-papst were chosen for the wheel motors. “Of course the energy efficiency of the drives also plays a major role for us,” he says. “After all, the mower should work for as long as possible without charging.”
Armin Pokorny is Industrial Drive Technology Market Manager at ebm-papst and is Younadam’s contact person for the project. He recalls: “In order to meet the speed requirements of the CEORA developers, we have adapted the standard motors’ windings. So Husqvarna can retrieve the maximum power at 36 volts. A transmission with the special Performax Plus 63.2 gear reduction is also used.”
The energy efficiency of the drives plays a major role for us. The mower should work for as long as possible without charging.Bilader Younadam, Electro-Mechanical Motor Design Engineer
Hard work generates a lot of heat. To ensure that the drive does not get too hot, the engineers at ebm-papst put holes in the motor’s standard hood: “We affectionately call it the Swiss cheese hood,” says Pokorny, laughing. “The cutouts in the aluminum cap now ensure that the heat is reliably dissipated and thus achieves the maximum motor power.”
When things get tough
There are stringent requirements for the robustness of the components too. For example, the CEORA mower and the transmission also have to withstand falling from certain heights. “We reinforced the bearings accordingly and manufactured the output shaft of the transmission from a more stable, rust-free material. This enabled us to meet the requirements,” says Pokorny. In a professional mower, the noise also plays a role, as Younadam emphasizes: “For our customers, it is very important that the mower operates as quietly as possible. Here, too, ebm-papst has found the right solution and designed the motors accordingly.”
Active wheel brushes are used so that the cut grass does not adhere to the wheels. They rotate while the mower is moving, removing the grass residues – with a double benefit: The CEORA can continue mowing without being disrupted and no lumps of grass remain on the lawn. The small brushes are driven by the ECI-42 wheel brush motors with the Performax Plus transmission from ebm-papst. They also excelled in terms of energy efficiency and durability.
Precise without a wire limit
It is worth noting that the CEORA does not use a boundary wire laid on the ground like usual robotic mowers. Instead, it uses the most up-to-date satellite technology. Younadam explains, “We use the Husqvarna Exact Positioning Operating System (EPOS) here. The users define the working areas virtually. The mower is then given a highly precise position using the satellite system. It operates at exactly the set limits up to two centimeters.” On defined transport routes, the CEORA will switch between different work areas and finds its own way to the charging station if the battery needs more power.
Users do not only specify where it needs to work, but also when and at what cutting height. “The frequent, systematic and highly precise mowing ensures perfect results, as only a small quantity is cut each time. It ensures that the turf is always optimally ventilated and grows in a lush green color,” explains Bilader Younadam. And at all times, the CEORA robotic mower very quietly goes about its work and leaves a perfect green space strip after strip, which awaits the next big event.