Many power and signal connectors are used in robot and drone sub-systems, such as sensors, motion, high-speed wired and wireless communications, and more. As industry 4.0 continues to unfold, more robots and more types of robots are being found in factories, warehouses, and other facilities to increase quality and efficiencies and reduce costs. Robots and drones are increasingly connected to the Industrial Internet of Things (IIoT) and the cloud, all of which require a growing arsenal of connector solutions.

This FAQ reviews four of the many types of connectors that enable the design of advanced robots and drones, including:  shielded and unshielded circular connectors that support a variety of communication protocols; rugged industrial RJ45 connectors for high-speed Ethernet and power-over-Ethernet (PoE); micro connectors that offer either encoder or power and brake connections for motion control; and magnetic self-mating connectors for mobile robots and drones that feature a breakaway safety function.

Circular connectors

Circular connectors are cylindrical and designed to securely and easily connect and disconnect signal, power, and optical circuits by hand without using any tools. The cylindrical housing contains an insulating material that holds, aligns, and insulates the contacts. Circular connectors are made in various sizes and pin counts, with and without shielding. The housings can be straight or angled and have varying levels of ingress protection (IP) ratings to meet the needs of a range of industrial operating environments.

The connection between the contacts and cable is designed to be highly resistant to accidental disconnection and environmental intrusions. These connectors are widely used in aerospace, communications, renewable energy, industrial, medical, and transportation systems. While there are a variety of circular connector standards, M5 to M58 circular connectors are widely used in industrial systems. “M” refers to the metric threads used with these connectors, and the number refers to the thread size in millimeters.

Robotic end-of-arm tooling (EOAT) is an example of a robotics function that often employs circular connectors for signal, data, and power. For example, M5, M6, and M7 are the smallest connectors in this series and are used in transportation and communications systems in addition to robotics and other industrial devices. M8 to M12 connectors are mainly used for data and signal connections with transmission speeds up to 10 Gbps, but certain designs also include power connections. Larger connectors up to the largest M58 are primarily power connectors rated for up to 150 A and 630 V.

M5 to M12 circular connectors can support various applications, power levels, and protocols (Figure 1). M8 and M12 connectors are commonly found in industrial automation systems, including robots. M8 connectors are often found in industrial sensor applications as well as PLCs and environmental controls. The M12 connectors are available with 3, 4, 5, 8, and 12 pins and are used in a broader range of factory automation applications for actuators, sensors, industrial Ethernet, and Fieldbus.

M12 connectors are used in many automation applications and are available with several coding styles to prevent mismating. IP ratings vary from dust-tight and water-resistant IP 65 to IP 68, protected against complete and continuous submersion in water. Five common types of M12 connector codings include:

A-coded connectors are common in robotics and other industrial equipment. Pin numbers vary from 2 to 12, and A-coded M12 connectors are used with actuators, motors, sensors, and other devices and can deliver DC power and signals.

B-coded connectors usually have three to five pins and are used for network interconnects such as Fieldbus in robotics, Industry 4.0, and Industrial Internet of Things (IIoT) devices.

C-coded connectors are most often used with AC-powered devices and are not as common in robots. They usually have three to six pins and include a dual keyway for increased security and reliability.

D-coded connectors usually have 3 to 5 pins and support data rates up to 100 Mb, making them suitable for Ethernet and ProfiNet networks running industrial protocols such as Ethernet/IP and EtherCat.

X-coded connectors have 8 pins and can transfer up to 10 Gb of data using Ethernet connections. They are well-suited for high-speed data transfer in industrial robots, machine vision, and similar applications.

Data connectors

In addition to D-coded and X-coded M12 circular connectors, rectangular RJ45 industrial-rated connectors are used for Ethernet networking and can deliver data rates of 10/100Mbps and 1Gbps. While M12 connector and cabling systems are not generally fabricated in the field, field-installable RJ45 cable connectors are available for two-pair (10/100Mbps) and four-pair cables (1G/10Gbps) supporting Cat5e, Cat6, and Cat6A (Figure 2).

Compared with their M12 counterparts, RJ45 connectors are pretty flexible. In addition to various physical implementations, the performance of RJ45 connectors can be customized using Ethernet magnetics, filters, shielding, and deliver PoE, PoE+, and PoE++ (IEEE 802.3af, IEEE802.3at, and IEEE802.3bt). Some RJ45 connector systems are available in MIL-DTL-38999 and 26482 circular metal shell configurations with 360 degrees of EMC shielding and mechanical protection.

M12 vs. RJ45

It’s not really an “either-or” situation. M12 and RJ45 connectors can be complimentary. Both are available with compliance to IEC 11801:2002 Cat5 and can be used together for different purposes in a system. For example, molded M12 D-coded to RJ45 cordsets are available for applications that use a combination of RJ45 and M12 Ethernet connections, for instance, within control cabinets, large robots, industrial machinery, and outdoor systems. If a coreset is too much, couplers are available that can connect X-coded or D-coded M12 connectors directly with RJ45 Ethernet cabling. These couplers support Cat5, Cat6, and Cat6A and deliver PoE+ powering capabilities. Another option is to combine RJ45 connectors with mini circular connector formats (Figure 3). The RJ45 connector delivers Ethernet connectivity and power and the mini circular connector format delivers environmental protection not possible with even ruggedized RJ45 connectors.

Compact, Micro, and Magnetic Connectors

Moving toward smaller solutions can benefit from using a panel-mount rectangular connector system for industrial robotics and factory automation. These compact connector systems can occupy about 1/15^th of the space of heavy-duty connectors. They are designed for use in industrial robots in manufacturing and clean-room settings and support up to 15 A of signal and power in up to 50 circuits with pin pitch sizes from 3.00 to 6.00 mm. Rated for 100 mating cycles and an operating temperature up to 105°C, the terminal housings snap into panel-mount shells without any tools speeding field installation and maintenance. Crimp terminations further reduce costs and simplify wiring.

Even smaller, at the other extreme from large modular heavy-duty connectors that can deliver dozens of signal lines and optical communications, pneumatic connections, and power delivery, are micro connectors optimized for motor drive and control in medium- to medium- to small-sized robots (Figure 4). Small motor drive and control connectors are available to serve specific functions, such as a 9-position encoder connector (8 signal pins plus a ground pin) and a 4+2 power and brake connector. These small vibration-resistant connectors are compatible with standard-sized industrial cabling. The IP67 rated power and brake cable are rated for 380 Vac and 5 A of power and 48 Vdc and 2 A for braking. Combining power and brake into one connector results in a smaller solution, with faster and simpler assembly, increasing productivity and reliability.

Magnetic self-mating connectors have been developed for use in various light electric vehicles, including unmanned ground vehicles, autonomous robots, drones, e-bikes, and similar devices. These connectors include power contacts that can handle up to 40 A and 60 V, as well as contacts for data communication.

When the plug is placed near the socket, the magnetic force pulls and guides it into the socket, ensuring a correct and secure connection. In addition, these connectors are designed to break the connection when a pre-determined tensile force is applied to the connector (Figure 5). Automatic disconnection upon application of a tensile force reduces the risk of injury to personnel in the vicinity of e-bikes, mobile robots, and drones. It supports simple, one-handed deliberate disconnection of the system.

They are especially suited for use in applications where frequent connections and disconnections are required, such as battery charging. Active hot plugging can be enabled by using the data contacts to activate power flow after a connection is completed.

For example, these connectors are used in EnergyBus systems for charging electric bicycles and pedelecs within Europe. The connector can easily handle the 1.5 kW EnergyBus charging specification. The connector is circular and specified to charge light electric vehicles up to 1.5 kilowatts. The power pins are not energized until communication has been established and the system has been initialized to prevent arcing. The magnetic self-mating EnergyBus connector contains six contacts:

• 2 pins, for DC power transfer up to 1.5 kW at 12 to 48 Vdc at a maximum of 30 A.
• 2 pins, for CAN bus data communication
• 2 pins, for auxiliary DC power for non-power components, such as sensors and energy management.

Summary

The applications for robots and drones are proliferating in Industry 4.0 and the IIoT, and so are the variety of connectors needed to support various robot and drone designs and deployments. Connector choices include highly standardized circular connectors such as the ‘M’ series, extremely flexible variations on RJ45 connectors that can support high-speed Ethernet and various flavors of PoE, adapters for interconnecting RJ45 and M12 connector implementations, and highly compact panel-mount rectangular connector systems and magnetic self-mating connectors optimized for quick connects and disconnects from drones and robots.

References

Circular Connectors M5 to M12, Phoenix Contact
Compact Robotic Connectors, Molex
High-density inserts leave more space for robotics, Harting
M8/M12 Connector System, TE Connectivity
Micro Motor Connectors, TE Connectivity
Power and Data Transmission for LEV, Rosenberger
Solutions for the future: robotic connectivity, Phoenix Contact