Inductive Coupling: Simple Concept for Complex Automation – Part 2

Image provided by Yaskawa America, Inc., Motoman Robotics Division
Image provided by Yaskawa America, Inc., Motoman Robotics Division

In the new era of flexible or customized manufacturing, where manufacturers are producing multiple products on the same production line or performing multiple operations in the same space, robotics is becoming cornerstone of automation. Industry innovators are applying a robot’s agility and multipurpose form to solving some real life challenges and stretching horizons of possibilities to all new levels. These next generation applications bring with them a new complex age of automation that was nearly unthinkable a decade ago.  When we think about flexible manufacturing what comes to mind first are the challenges of handling product changeovers. With robots that would mean changing out the end-effectors so the robot is ready quickly for next operation.

Figure 1: Tool changer example with pin couplers
Figure 1: Tool changer example with pin couplers

With the current trends in automation, demand for robotic tool changers (quick change for end-effectors) is growing at a fast pace. This is not only limited to automotive or heavy industries but also in packaging, bakery automation, food and pharma, and importantly in life sciences. End effectors are where these innovators primarily focus on to create value for their customers by handling products in most application suitable way.  The smarts of the end effectors, sensors and actuators, need power and the ability to communicate with the controller. Traditionally, this is achieved with pin-based coupling, where the robot approaches the tool changing station, engages the tool and very accurately mates the two ends of the pin couplers to power up the tool’s smarts.

The pin based coupling is effective and widely used today but it has few of its own issues: First, the pins of the tool when not in use are open and exposed to the environment- accumulation of dust, water or oil- causes nuisances in the connection process. Second, these are mechanical contacts and over time they wear out, bend, or break and cause un-intended downtime in the application.

Inductive coupling addresses all these issues and adds further value to automation. As explained in my previous blog. Both sides of the inductive coupler (Base and Remote) are fully encapsulated, typically with IP67 protection class, so that these couplers have no environmental issues to worry about. Since both sides are magnetically coupled, they are immune to vibrations. And, yes, since there is no-contact between the base and the remote side, there are no worries about bending or breaking of the pins.

Inductive coupling with IO-Link technology adds more benefits besides replacing the pin coupling. IO-Link enabled inductive couplers allow transferring up to 32 bytes of data in addition to power for actuation or sensors. When you connect IO-Link enabled I/O hubs or valve connectors to the remote side, (as shown in the picture below) you can also store identification data on the IO-Link hub or valve. When the connection is establish the controller can request the identification data from the tool to ensure that robot or system is utilizing the correct tool for the upcoming process. You might say, “wait a minute– this identification is also possible with pin-based coupling, so what is so great about inductive coupling?” Great question! With pin based coupling you first need to engage the tool to mate the two ends of the pin couplers and then request the identification. Up to 4-5 seconds are wasted before you realize it is a wrong tool. With inductive coupling, just the base need to be brought closer to the remote so that you could quickly couple and identify the tool before engaging the tool– saving you precious seconds. Coupling usually takes less than a second and most importantly the base and remote do not need to be well aligned to couple misalignment up to 15-20 degrees of angular offset or 2-4mm of axial offset still provides functionality.


So, you may ask, what are the limitations with Inductive coupling? The most important factor is how much energy your tool’s smarts require. Generally speaking 24W-48W is probably the most commonly available inductive couplers. If your tool requires any more than that then pin based coupling is the way to go. Another deciding factor is – metal dust in the environment. In the presence of metal dust on the surface of the couplers may cause interruptions in the communication as the basis of the communication is magnetic induction.

I hope this blog helps you decide the right coupler for your next application. In the next blog of this series we will review how inductive coupling can simplify automation along the assembly lines.

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