Use Contactless Power and Data Transmission for Wear-Free and Low-Maintenance Industrial Solutions

Flexible and highly reliable connections are essential in industrial applications, such as those used in robot tools and rotating devices like precision indexing tables. Those systems experience high movement and rotation and are often exposed to dirt and vibration that can cause conventional connectors or slip rings to fail.

Designers need new options to overcome the limitations of conventional solutions in these and other challenging applications. The new option must be able to support secure duplex Ethernet connections up to 100 Mbps and transfer up to 50 W of power for sensors and other components across a gap of 12 mm (or 40 mm for data only).

Flexible mounting options are necessary to support a wide range of system designs, and a simple, visible LED indicator is required for quick diagnostics.

Operation in harsh industrial settings requires an IP65 environmental rating, and the solution must meet IK06 per EN 62262, indicating that it can withstand external mechanical impacts with an energy of up to 1 Joule. Simple installation or replacement can minimize maintenance costs and downtime.

This article begins with a brief review of the challenges associated with using conventional connectors and slip rings in various industrial applications. It then delves into the capabilities of the NearFi couplers from Phoenix Contact, detailing how they address the electrical, mechanical, and security needs for contactless power and data transmission in challenging industrial applications.

Robot reliability challenges

Frequent tool changes for robots used in automated assembly processes can present significant challenges for connectors. Those tool changes can require hundreds of mating/unmating cycles every day.

Each cycle exposes the contacts to contaminants and causes wear due to contact friction. If the connectors are not precisely aligned, contacts can get bent.

The result is reduced connector reliability and unpredictable downtime for maintenance. In addition to connectors for tool attachment, some robots utilize slip rings for the transmission of data and power in rotating arms and joints.

Slip ring limitations

Slip rings can also be found in wind turbines, as well as in food and pharmaceutical processing and packaging lines, and other industrial processes. Like conventional connectors, slip rings can be damaged by exposure to contaminants and can experience excessive mechanical wear.

Slip rings can become hot due to friction and may require attention to thermal management. In some applications, slip rings can be subjected to strong vibrations or sudden impacts that can result in damage, cause unstable contact pressure, or even mechanical failure.

Both conventional connectors and slip rings can create machine design challenges related to size and movement constraints, as well as access requirements for maintenance. This adds to the numerous application challenges, including intermittent connections caused by vibration, dust, dirt, and contact wear, among others.

NearFi solution

Using “better” connectors may offer an opportunity for incremental improvement in performance or reliability. But what’s really needed is an out-of-the-box approach that eliminates the most vexing connector challenges. That’s NearFi.

NearFi is a non-contact technology that supports wear-free and reliable communication and power delivery across an air gap of a few centimeters or through non-metallic materials, such as plastic, glass, and wood. When transmitting only data, NearFi can connect across an air gap of 40 mm. Power, or combined power and data transmissions, can connect across an air gap of 12 mm.

NearFi uses 60 GHz wireless technology to transmit data and inductive coupling to deliver power from a base coupler to a remote coupler. Couplers feature a housing rated IP65 and IK06, along with M12 connection technology, ensuring wear-free and maintenance-free operation in demanding industrial environments.

The NearFi system gives designers a choice of three solutions:

• Data and power can be transferred simultaneously using the 1234224 base coupler with the 1234225 remote coupler.
• Power can be coupled without data support using the 1234226 base with the 1234229 remote.
• Data can be transmitted without power using the 1234232 base with the 1234234 remote.

Full-duplex Ethernet

With NearFi, data is exchanged simultaneously in both directions without latency. The use of two parallel 60 GHz connections on separate frequency bands, one for the uplink and one for the downlink, enables full-duplex real-time data transmissions. This makes it suitable for time-critical industrial protocols, such as PROFINET and EtherCAT. Since the transmission technology is protocol-independent, it can be used with any standard Ethernet protocol (Figure 1).

Figure 1: NearFi supports protocol-agnostic, full-duplex 100 Mbit/s Ethernet. (Image source: Phoenix Contact)

The use of near-field communication (NFC) is a key factor in NearFi performance. Unlike conventional far-field communication, which relies on propagating electromagnetic waves that travel indefinitely through space, the energy in NFC does not radiate out indefinitely. It decays rapidly with distance. NFC is a low-power technology that further mitigates the possibility of electromagnetic interference (EMI).

The use of NFC also ensures reliable coexistence with existing wireless technologies, such as WLAN or Bluetooth. Also, standard industrial interference spectrums don’t impact NearFi transmissions, eliminating the need for frequency planning when deploying NearFi.

The limited range means that multiple NearFi links can be run in proximity without interference. The bottom line is that NFC enables reliable, maintenance-free, high-speed data transmissions with substantial immunity to EMI. Finally, an LED ring on the coupler housings displays the connection status and facilitates troubleshooting, thereby speeding up setup and diagnostics.

Bit-oriented transmissions

The use of a synchronous, bit-oriented transmission technology is another key to NearFi’s performance. Bit-oriented technology contrasts with the packet-oriented transmission of other wireless communications.

Packet-oriented implementations generally suffer from significant latency. The data arrives at the transmitter and must be put into packets before transmission. At the receiver end, the packets are unpackaged before the data is output to the system.

In NearFi synchronous transmissions, data is sent directly, bit by bit, as it arrives, with no packing or unpackaging. That produces a continuous data stream and virtually eliminates latency. That’s why NearFi is well-suited for time-critical industrial Ethernet protocols, such as time-sensitive networking (TSN), PROFINET, and EtherCAT (Figure 2).

Figure 2: NearFi utilizes bit-oriented transmissions to mitigate latency challenges commonly associated with traditional packet-based communication. (Image source: Phoenix Contact)

In addition, since the data is transmitted without buffering or packaging, NearFi is protocol-transparent and can handle any Ethernet protocol without requiring configuration.

NearFi addresses security concerns by limiting communication to a short distance. It can also support high-level security measures, such as encryption, authentication, and tokenization.

Delivering power

The NearFi system utilizes inductive power transmission with a frequency range of 100 to 148.5 kHz, similar to that used in some smartphone wireless chargers. Up to 50 W (24 V_DC, 2 A) can be transmitted, and with parallel connection, up to 100 W.

Active closed-loop control delivers constant power transmission over the entire working area. The transmission of two electrically isolated voltages (each 50 W) is also supported. Like data connections, power delivery uses a base coupler and remote coupler.

The base coupler receives 24 V_DC power from a source, such as a controller. The integrated communication power/sensor voltage converter, also known as the US converter (where "U" is the notation for voltage in German), converts the 24 V_DC power into high-frequency power for inductive transmission. The remote coupler receives high-frequency inductive power and converts it back to 24 V_DC in the UA (actuator voltage) converter for use in I/O, switches, sensors, actuators, and other functions (Figure 3).

Figure 3: Power is inductively coupled between the base coupler to the remote coupler. (Image source: Phoenix Contact)

Fast Startup

The NearFi Fast Startup function enables the quick (<500 ms) reestablishment of real-time links. That’s possible because power transmission and data communication begin while the NearFi couplers are still in the process of approaching each other.

Fast Startup can significantly reduce cycle times in applications like robot tool changes (Figure 4). The bidirectional data transfer capability of NearFi also enables the new tool (or other attachment) to identify itself to the system, confirming that it’s the correct item.

Figure 4: Possible use of NearFi in a robot tool changing station. (Image source: Phoenix Contact)

More application ideas

NearFi couplers can be brought together facing each other, with an offset, or at a tangential angle. They can also be used in applications where the base coupler is stationary while the remote coupler rotates (Figure 5). NearFi couplers are ready to use out of the box, eliminating the need for programming and speeding up application development and deployment.

Figure 5: In this application, the remote coupler on the left is rotating while the base coupler on the right is stationary. (Image source: Phoenix Contact)

The same features that make NearFi suitable for use in robot tool changes can also support the needs of applications such as automated guided vehicles (AGVs) and material and workpiece carriers.

Rotating antennas, such as those found at airports, can benefit from replacing conventional slip rings with NearFi couplers. Similarly, precision indexing tables are used in industrial applications, as well as in bottle fillers within the food and beverage and pharmaceutical industries.

Conclusion

NearFi technology solves a host of seemingly intractable problems. It wirelessly delivers protocol-agnostic 100 Mbit/s Ethernet, plus 50 W of power, and is flexible and easy to use. NearFi couplers are designed for use in harsh industrial settings, featuring IP65 and IK06 ratings, as well as M12 connectivity. How will you use NearFi to differentiate your next design?

Recommended reading:

1. New PLCs Help Speed the Deployment of Complex and Critical Automation Processes
2. Deploying Predictive Maintenance for the Maximum Benefit in Industry 4.0 Facilities
3. Motion Performance Considerations when Selecting VFD Cables for Robotics
4. Optimizing Industry 4.0 Communication Architectures using Multi-Protocol I/O Hubs and Converters
5. How to Overcome the Challenges of Developing Engaging User Interfaces for the Metaverse