Intralogistics without a cable carrier – contactless energy and data transfer
How are product-related intralogistics processes completed as quickly as possible in machinery or systems? And how can this material flow be made as efficient and compact as possible? SEW‑EURODRIVE has joined forces with EMAG to produce an innovation – a gantry robot with optical and inductive signal and energy transfer.
Some years ago, we therefore started developing our own automation solutions with the aim of being able to respond as flexibly as possible to customer demands. We're first and foremost a machine tool manufacturer, though, so we decided to look for a strong partner to help us further develop this automation technology. We required electrical and control engineering support in particular.
It didn't take us long to decide on SEW‑EURODRIVE.
After all, the two companies enjoy a trusting business relationship dating back many years. I'm delighted we were already able to present an initial result of this collaboration at SPS 2018, with EMAG developing the mechanical components and SEW‑EURODRIVE all the power, electrical, and control engineering.
We remove sections of machinery from the chain, which mobilizes the associated resources and makes systems as a whole more flexible and productive for the future. It also removes the need for a separate controller in each robot.
In mechanical engineering intralogistics, gantry robots are the standard, tried-and-tested system solution for the material flow between machines or production centers. Cable carriers are normally used to carry the power and data cables.
Our ground-breaking innovation for Cartesian robots now puts an end to these inflexible energy chains that take up a lot of space. This is possible thanks to an intelligent system solution with optical and inductive signal and energy transfer .
Great freedom for logistics processes
This is how intelligent a gantry robot intralogistics solution can be: Free horizontal movement of several robots on the same route paves the way for logistics processes that would be virtually impossible with energy chains. Even overlapping sections are possible with this solution.
Energy chains, on the other hand, need to move continuously along with the system, so it would be necessary to have far larger masses on the move. This would generate more noise, cause significant wear, and negatively affect system dynamics. The resulting friction would also make energy consumption unnecessarily high, so it's just as well the new solution makes all that a thing of the past at EMAG.
The MOVITRANS ® inductive energy transfer system and the decentralized TES power supply module make the design of our system solution for gantry robots exceptionally smart. There are no longer any restrictions relating to construction space, wear, energy consumption, or potential cable breakage . Freedom and excellent dynamics have replaced limited cycle rates as the new standard. Our modular machine automation now supports a transmission power of between 3 and 8 kW.
Storing rather than wasting energy
EMAG is particularly excited about the automation solution's energy balance. Although acceleration on the horizontal axis alone requires over three kilowatts of power, the robot consumes less than 500 watts via the MOVITRANS ® pick-up over the entire load cycle.
The trick here is that the decentralized MOVI‑DPS ® storage solution meets the application's short-term energy requirements. This unit (DPS = Drive Power Solution) is a double-layer capacitor package that is responsible for supplying the robot with a DC link voltage of 100 V DC .
But where does this energy storage solution's power come from? A look at a gantry robot and/or its typical travel profile reveals that acceleration phases alternate with braking phases. Instead of dissipating the regenerative energy generated during the braking phases via resistors – as is normally the case – the SEW‑EURODRIVE solution uses the decentralized energy storage unit to retain this braking energy within the process.
The DPS energy storage system works in the same way as a booster when the gantry's drives accelerate the robots from zero to six meters per second. A huge amount of energy is saved, because with this MOVITRANS ® solution, only mechanical losses need to be compensated . Consequently, the system consumes a total of just 500 watts for one load cycle .
Reliable optical communication in real time
Communication in the gantry robot also takes place without any accompanying cables. Instead, a data light barrier is used for the EtherCAT real-time Ethernet protocol as an optical connection to the mobile units. This data light barrier enables the drive data to be transferred to the mobile units in the system in cascades, which removes the need for a separate controller for each robot. Each cycle takes just one millisecond – with virtually no latency periods to be taken into account when transmitting the interpolatable position setpoints to the controllers and/or providing feedback on the actual values.
The communication required for functional safety also takes place via EtherCAT. All mobile units and the machine as a whole are connected via a central safety controller. The EtherCAT safety protocol FSoE ( F ail S afe o ver E therCAT) is used for this purpose, establishing direct communication between the safety controller and the MOVI-C ® CONTROLLER.
This solution enables straightforward data exchange between the two controllers, simplifies programming, and creates ideal diagnostic and debugging conditions thanks to the information density obtained.
This application demonstrates that both an FSoE safety master and an EtherCAT data light barrier can be integrated seamlessly into SEW‑EURODRIVE automation solutions.
A simple and flexible solution to robot motion control
Just one central controller for up to four mobile robots: A MOVI-C ® CONTROLLER from our modular automation system MOVI-C ®calculates the complex robot motion control .
Calculating motion profiles requires collision avoidance and precise coordination of the robots involved, especially with a view to the productivity of the application as a whole .
The machine automation solution from SEW‑EURODRIVE is so versatile that users can respond quickly and flexibly to any changes. If one of the machines in the production network requires double the material flow, for example, the solution is sufficiently adaptable to allow a robot to be taken from the gantry system and used for this purpose.
The enhanced mobility of their resources will make "off-chain" sections of machinery far more flexible and productive in the future.