Optimized Motion Solutions Drive Safelog’s AGVs Ahead of the Competition

Tom Deanovic, Dennis Wöppel, Franz Haas and Safelog CEO Mathias Behounek (from left to right) with a current generation AGV type AGV M4. – Image: TeDo publishing GmbH

Tom Deanovic, Dennis Wöppel, Franz Haas and Safelog CEO Mathias Behounek (from left to right) with a current generation AGV type AGV M4. – Image: TeDo publishing GmbH

Servo Drive Technology in Automated Guided Vehicles

More Drive for the Robot

Automated Guided Vehicles (AGVs) and mobile robots are considered key elements for modern manufacturing structures. Safelog has made a name for itself as a provider of such solutions, supplying the automotive industry with large quantities. The SPS-MAGAZINE visited the site in Markt Schwaben near Munich to find out what role the drive technology from STXI Motion plays in the success of the driverless units.

At the end of 2019, STXI Motion entered the market as a spin-off from the Israeli drive provider Servotronix. From the beginning, the young company focused on the growth market of mobile applications, such as AGVs. “The initial spark was the desire to position ourselves more strongly in the – from our point of view very attractive – low-voltage area,” explains Dennis Wöppel, Key Account Manager at the German STXI Motion branch in Nettetal. “Intralogistics was then a logically derived target segment.”

Safelog became one of STXI’s first customers in this market. And as is often the case, it all started with an idea. “The idea for a drive system for the drive axle,” reveals Wöppel. “We presented this at a meeting in Markt Schwaben at the beginning of 2020.” Although the AGV manufacturer had different ideas regarding power class and interfaces, this marked the beginning of the dialogue. “The collaboration really started a few months later, when we began developing the AGV model M4,” recalls Franz Haas, Product Developer at Safelog. The M4 was to mark the start of a new generation of mobile robots. “Consequently, we devoted extensive attention to the question of the suitable drive.”

In the first step, Safelog formulated a list of requirements and, in the second step, began testing various drive solutions – a process that lasted several months. Among them was a servo solution from STXI. And this time, it convinced them. “Our current partner got the nod at the beginning of 2021,” continues Haas. “Since then, we have been working very closely together.” Because it was necessary to further adapt the drive system to the requirements of the mobile transport robots. At the same time, the focus of the collaboration expanded.

While initially it was only about a 500W drive for the new AGV M4, the Safelog developers soon also discussed suitable drive variants for the integrated lifting systems of the mobile transport robots with STXI. After all, the aim was to concentrate on one drive supplier as much as possible in the spirit of the one-stop-shop idea. “We also try to keep the technology of our robots modular,” says Haas, “so that the installed drive technology can be used across different models.” Accordingly, Safelog’s goal is to solve all driving, steering, and lifting tasks from the same modular system. This approach is not only advantageous in terms of purchasing and communication with the supplier but can also save a lot of time and effort in development.

Tough Requirements

Regarding the properties of the servo technology, Safelog places high demands on its supplier. “Our AGV solutions have to become ever more compact, and for this, the drive technology is crucial,” emphasizes Tom Deanovic, Head of Hardware Product Development at Safelog. Dimensions and form factor are just two of many points in the AGV manufacturer’s specification. High power density is also essential. “And even the best performance is useless without the necessary reliability and quality,” Deanovic points out. “After all, we design our mobile transport robots for a lifespan of ten to fifteen years.”

“A key criterion is also the collaboration itself,” Franz Haas expands the requirements to include soft skills. “The chemistry has to be right – and that was immediately the case with STXI.” Moreover, it was important for Safelog to have a contact in the region who not only speaks the same language but can also be on site promptly if necessary.

Close Exchange

“The high expectations of Safelog necessitate a very close exchange,” confirms Dennis Wöppel. Accordingly, the supplier has invested a lot of time in the collaboration. As a result, all the customer’s wishes could be implemented, and the drive technology well adapted to the specific requirements. “To be honest, this journey is not yet complete,” says the Key Account Manager. “Although we have come so far together, it remains an ongoing process.” Tom Deanovic adds: “And that’s a good thing. Because the more drives from STXI we integrate into our mobile transport robots, the more new tasks there are to discuss and solve.”

A challenge for the drive manufacturer is that Safelog develops new AGV solutions exceptionally quickly. “Casually put: they spring up from the ground,” Wöppel says with a wink. The AGV M4 model already went into series production in the summer of 2021 – bearing in mind that the drive manufacturer had only received the nod at the beginning of the year. In the meantime, the new AGV generation has been expanded by two more types. The last family member is to be available shortly. In total, the four AGV models M4, S3, L2, and X1 will then be on the move with STXI technology. The fact that production is still completely based at the headquarters in Markt Schwaben near Munich plays into Safelog’s hands in terms of development speed. “However, we need suppliers who can keep up with this pace,” Deanovic emphasizes. Wöppel notes: “To achieve this, as a supplier, we must not only react quickly but also stay on the ball with a lot of passion.”

Great Trust

The close cooperation – which goes far beyond the classic customer/supplier relationship – requires great trust on both sides. After all, the partners look closely at each other’s cards. “The more the STXI team knows about our products and use cases, the better it can tailor the drives to our needs,” says Deanovic. The reverse is also true: “The better we understand which drive screws can be turned, the more targeted our suggestions for improvement are.” “Just talking to each other is not enough. You have to develop an understanding of what the other side really needs,” emphasizes developer Franz Haas the importance of application competence. “And for that, it’s essential for suppliers to come to us, to look at the production and the vehicles – and to discuss possible solutions openly.” In the process, features have sometimes emerged that originally neither side had on their radar.

Drive and Controller in a Package

To return to the topic of one-stop shopping. STXI not only supplies the robot manufacturer with various motor gear units but also delivers the matching drive controllers in a package. “This way, we can be sure that both – motor and controller – function flawlessly together,” explains Deanovic.

The wheel drive system mobiMS is precisely tailored to the needs of mobile robots and automated guided vehicles. The motor gear unit mobiGM consists of a brushless servo motor, a planetary gearbox, spring-applied brake, and encoder. It is characterized by high torque density. The compact and integrated design saves space and simplifies both cabling and the mechanical design of the mobile unit. The strong drive bearings and the shock- and vibration-resistant servo system also allow high payload capacities of the AGVs. The comparatively low power consumption keeps charging cycles short and allows for greater range.

The central link to the control electronics is the low-voltage servo controller servSD, which allows for a motor-close, space-saving installation with its compact dimensions of 10x106x74mm. With the safety function STO (Safe Torque Off), it meets Safelog’s current requirements for safe operation. The connection to the AGV control is via CAN bus, so that each drive can be controlled individually. Just from the encoder data and information from the motor, Safelog can already precisely deduce how the mobile transport robot behaves.

Suitable Solutions

International certification of the components installed in the mobile robots is an important prerequisite for Safelog. “Since we are also active in the American market, UL certification was quickly completed,” Wöppel says. In total, the drive spectrum used by Safelog for the current AGV generation now includes two different controller variants as well as six different STXI motors. “With this, we can cover a lot,” concludes Tom Deanovic. “And should we soon find that we need another variant or adaptation on the motor or controller side, then we are sure that.


Safelog manufactures its AGVs entirely at its German headquarters and implements new developments exceptionally quickly. Suppliers like STXI must be able to keep up with this pace. – Image: TeDo publishing GmbH

Safelog manufactures its AGVs entirely at its German headquarters and implements new developments exceptionally quickly. Suppliers like STXI must be able to keep up with this pace. – Image: TeDo publishing GmbH

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