Sensor and Device Connectivity Solutions For Collaborative Robots

Sensors and peripheral devices are a critical part of any robot system, including collaborative applications. A wide variety of sensors and devices are used on and around robots along with actuation and signaling devices. Integrating these and connecting them to the robot control system and network can present challenges due to multiple/long cables, slip rings, many terminations, high costs to connect, inflexible configurations and difficult troubleshooting. But device level protocols, such as IO-Link, provide simpler, cost-effective and “open” ways to connect these sensors to the control system.

Just as the human body requires eyes, ears, skin, nose and tongue to sense the environment around it so that action can be taken, a collaborative robot needs sensors to complete its programmed tasks. We’ve discussed the four modes of collaborative operation in previous blogs, detailing how each mode has special safety/sensing needs, but they have common needs to detect work material, fixtures, gripper position, force, quality and other aspects of the manufacturing process. This is where sensors come in.

Typical collaborative robot sensors include inductive, photoelectric, capacitive, vision, magnetic, safety and other types of sensors. These sensors help the robot detect the position, orientation, type of objects, and it’s own position, and move accurately and safely within its surroundings. Other devices around a robot include valves, RFID readers/writers, indicator lights, actuators, power supplies and more.

The table, below, considers the four collaborative modes and the use of different types of sensors in these modes:

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But how can users easily and cost-effectively connect this many sensors and devices to the robot control system? One solution is IO-Link. In the past, robot users would run cables from each sensor to the control system, resulting in long cable runs, wiring difficulties (cutting, stripping, terminating, labeling) and challenges with troubleshooting. IO-Link solves these issues through simple point-to-point wiring using off-the-shelf cables.

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Collaborative (and traditional) robot users face many challenges when connecting sensors and peripheral devices to their control systems. IO-Link addresses many of these issues and can offer significant benefits:

  • Reduced wiring through a single field network connection to hubs
  • Simple connectivity using off-the-shelf cables with plug connectors
  • Compatible will all major industrial Ethernet-based protocols
  • Easy tool change with Inductive Couplers
  • Advanced data/diagnostics
  • Parametarization of field devices
  • Faster/simpler troubleshooting
  • Support for implementation of IIoT/Industry 4.0 solutions

IO-Link: an excellent solution for simple, easy, fast and cost-effective device connection to collaborative robots.

IO-Link reduces waste due to sensor failures

In the last two blogs we discussed about Lean operations and reducing waste as well as Selecting right sensors for the job and the environment that the sensor will be placed. Anytime a sensor fails and needs a replacement, it is a major cause of downtime or waste (in Lean philosophy). One of the key benefits of IO-Link technology is drastically reducing this unplanned downtime and replacing sensors with ease, especially when it comes to measurement sensors or complex smart sensors such as flow sensors, continuous position monitoring sensors, pressure sensors, laser sensors and so on.

When we think about analog measurement sensor replacement, there are multiple steps involved. First, finding the right sensor. Second, calibrating the sensor for the application and configuring its setpoints. And third, hope that the sensor is functioning correctly.

Most often, the calibration and setpoint configuration is a manual process and if the 5S processes are implemented properly, there is a good chance that the procedures are written down and accessible somewhere. The process itself may take some time to be carried out, which would hold up the production line causing undesired downtime. Often these mission critical sensors are in areas of the machine that are difficult to access, making replacing then, let alone configuring, a challenge.

IO-Link offers an inherent feature to solve this problem and eliminates the uncertainty that the sensor is functioning correctly. The very first benefit that comes with sensors enabled with IO-Link is that measurement or readings are in engineering units straight from the sensor including bar, psi, microns, mm, liters/min, and gallons/min. This eliminated the need for measurements to be scaled and adjusted in the programming to engineering units.

Secondly, IO-Link masters offer the ability to automatically reconfigure the sensors. Many manufacturers call this out as automatic device replacement (ADR) or parameter server functionality of the master. In a nutshell, when enabled on a specific port of the multi-port IO-Link master, the master port reads current configuration from the sensor and locks them in. From that time forward, any changes made directly on the sensor are automatically overwritten by these locked parameters. The locked parameters can be accessed and changed only through authorized users. When the time comes to replace the sensor, there is only one step that needs to happen: Find the replacement sensor of the same model and plug it in. That’s it!

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When the new sensor is plugged-in, the IO-Link master automatically detects that the replacement sensor does not have the correct parameters and automatically updates them on the sensor. Since the readings are directly in the units desired, there is no magic of scaling to fiddle with.

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It is also important to note, that in addition to the ADR feature, there may be parameters or settings on the sensors that alert you to possible near-future failure of the sensor. This lets you avoid unplanned downtime due to sensor failure. A good example would be a pressure sensor that sends an alert (event) message indicating that the ambient temperature is too high or a photo-eye alerting the re-emitted light value is down close to threshold – implying that either the lens is cloudy, or alignment is off.

To learn more about IO-Link check out our other blogs.

You have options when it comes to connecting your sensors

When it comes to connecting I/O in factory automation settings, there are many options one can choose to build an efficient and cost-effective system. This is one area where you can reduce costs while also boosting productivity.

Single Ended Cables and Hardwired I/O

It is common in the industry for single ended cables to be run from sensors to a controller input card in a centralized control cabinet. And while this method works, it can be costly for a number of reasons, including:

  • Flying leads on single ended cables are time consuming to prepare and wire
  • Wiring mistakes are often made leading to more time troubleshooting
  • I/O Cards for PLCs are expensive
  • Long cable runs to a centralized location add up quickly especially when dealing with analog devices which require expensive shielded cables
  • Lack of scalability and diagnostics

Double Ended Cables and Networked I/O

Using double ended cables along with network I/O blocks allows for a cost-effective solution to distribute I/O and increase up time. There are numerous benefits that come along with this sort of architecture. Some of these benefits are:

  • Reduced cabling — since I/O is distributed, only network cables need to be run back to the control cabinet reducing cost and cabinet size, and sensor cables are shortened since I/O blocks are machine mounted
  • Quicker build time since standard wiring is less labor intensive
  • Diagnostics allows for quicker trouble shooting, leading to lower maintenance costs and reduced downtime

IO-Link

Using IO-Link delivers all of the strengths of networked I/O as well as additional benefits:

  • I/O Hubs allow for scalability
  • Smart devices can be incorporated into your system
  • Parameterization capability
  • Increased diagnostics from intelligent devices
  • Reduced costs and downtime
  • Increased productivity

Inductive Coupling for non-contact connection

Many people are using inductive coupling technology to provide a non-contact connection for their devices. This method allows you to pass both power and signal across an air gap making it ideal for replacing slip rings or multi-pin connectors in many applications. This provides some great options for industry to gain benefits in these areas such as:

  • Reduced wear since there is no physical connection
  • Faster change over
  • Reduced downtime due to the elimination of damaged connector pins

For more information on connectivity and I/O architecture solutions please visit www.balluff.com.

M12 Connector Coding

New automation products hit the market every day and each device requires the correct cable to operate. Even in standard cables sizes, there are a variety of connector types that correspond with different applications.

When choosing a cable, it is essential to choose the correct size, length, number of connectors, pinout, and codes for your application. This post will review cable codes, which signify different capabilities and uses for a cable. Cables that are coded differently will have different specifications and electrical features, corresponding to their intended uses. To distinguish between the different styles of cable, each connector has a different keyway, as shown in Figure 1.  This is to prevent a cable from being used in an incorrect application.

Cable Codes-01

There are a wide variety of cable codings used for different purposes. Below are the five most common M12 cable codes and their uses. They are as follows:

  • A-coded connectors are the most common style of connector. These are used for sensors, actuators, motors, and most other standard devices. A-coded connectors can vary in its number of pins, anywhere between two pins and 12 pins.
  • B-coded connectors are mostly used in network cables for fieldbus connections. Most notably, this includes systems that operate with Profibus. B-coded connectors typically have between three and five pins.
  • C-coded connectors are less common than the others. These connectors are primarily used with AC sensors and actuators. They also have a dual keyway for added security, ensuring that this connector will not be accidentally used in the place of another cable. C-coded connectors have between three and six pins.
  • D-coded connectors are typically used in network cables for Ethernet and ProfiNet systems. D-coded connectors transfer data up to 100 Mb. These connectors typically provide three to five pins.
  • X-coded connectors are a more recent advancement of the cables. They are growing in popularity due to their ability to transfer large amounts of data at high speeds. X-coded cables transfer data up to 1 Gb. These are ideal for high-speed data transfer in industrial applications. While the other coded cables typically vary in number of connectors, X-coded cables will always have eight pins.

IO-Link Makes Improving OEE in Format Change Easier than Ever

One of the primary applications in Packaging, Food & Beverage that is a huge area for improving overall equipment efficiency (OEE) is format change.  Buyers respond well to specialized or individualized packaging, meaning manufacturers need to find ways to implement those format changes and machine builders must make those flexible machines available.

IO-Link Makes Improving OEE in Format Change Easier than Ever_2

Today, thanks to IO-Link devices, including master blocks, hubs and linear position sensors, improving OEE on format change is more possible today than ever before. IO-Link offers capabilities that make it ideal for format change. It communicates:

  • Process data (control, cyclical communication of process status)
  • Parameter data (configuration, messaging data with configuration information)
  • Event data (diagnostics, communication from device to master including diagnostics/errors)

What is format change and how does it impact OEE?

Format change is the physical adjustments necessary to make to a machine when the product is altered in some way.  It could be a change in carton size, package size, package design, case size or a number of other modifications to the product or packaging.  The time to adjust the machine itself or the sensors on the machine can take anywhere from 30 minutes to an entire eight- hour shift.

Types of format changes to consider when seeking to improve your OEE:

Guided format change is when the operator is assisted or guided in making the change.  For example, having to move or slide a guide rail into a new position.  IO-Link linear position sensors can help guide the operator, so the position is exact every time. This reduces time by eliminating the need to go back and look at an HMI or cheat sheet to determine if everything is in the right position.

Change parts is when a part needs to be swapped out on the machine for the next production run.  An example of this is when the bag size on a bagger or vertical form fill and seal (VFFS) machine changes and the forming tube needs to be changed.  Having an RFID tag on the forming tube and a RFID reader on the machine allows for easy verification that the correct forming tube was put on the machine and only takes seconds.

Color Change is when the color of a pouch, package or container changes for the next production run like when a yogurt pouch changes color or design while the size and shape remain the same as previous production runs. Smart color photo electric sensors can change the parameters on the photo eye to detect the correct color of the new pouch occurs instantly upon changing the recipe on the machine.

Developing semi-automated or fully automated solutions can improve OEE in regard to format change by helping reduce the time needed to make the change and providing consistent and accurate positioning with the ability to automatically change parameters in the sensor.

Being smart, easy and universal, IO-Link helps simplify format change and provides the ability to change sensor parameters quickly and easily.

IO-Link Makes Improving OEE in Format Change Easier than Ever_1

How TSN boosts efficiency by setting priorities for network bandwidth

As manufacturers move toward Industry 4.0 and the Industrial Internet of Things (IIoT), common communication platforms are needed to achieve the next level of efficiency boost. Using common communication platforms, like Time-Sensitive Networking (TSN), significantly reduces the burden of separate networks for IT and OT without compromising the separate requirements from both areas of the plant/enterprise.

TSN is the mother of all network protocols. It makes it possible to share the network bandwidth wisely by allocating rules of time sensitivity. For example, industrial motion control related communication, safety communication, general automation control communication (I/O), IT software communications, video surveillance communication, or Industrial vision system communication would need to be configured based on their time sensitivity priority so that the network of switches and communication gateways can effectively manage all the traffic without compromising service offerings.

If you are unfamiliar with TSN, you aren’t alone. Manufacturers are currently in the early adopter phase. User groups of all major industrial networking protocols such as ODVA (CIP and EtherNet/IP), PNO (for PROFINET and PROFISAFE), and CLPA (for CC-Link IE) are working toward incorporating TSN abilities in their respective network protocols. CC-Link IE Field has already released some of the products related to CC-Link IE Field TSN.

With TSN implementation, the current set of industrial protocols do not go away. If a machine uses today’s industrial protocols, it can continue to use that. TSN implementation has some gateway modules that would allow communicating the standard protocols while adding TSN to the facility.

While it would be optimal to have one universal protocol of communication across the plant floor, that is an unlikely scenario. Instead, we will continue to see TSN flavors of different protocols as each protocol has its own benefits of things it does the best. TSN allows for this co-existence of protocols on the same network.

 

Power & Force Limiting Cobots for Dull, Dirty and Dangerous Applications

Collaborative robots, or cobots, is currently one of the most exciting topics in automation. But what do people mean when they say “collaborative robot”? Generally, they are talking about robots which can safely work near and together with humans. The goal of a collaborative robot system is to optimize the use of humans and robots, building on the capabilities of each.

There are four modes of robot collaborative operation defined by the global standard ISO/TS 15066. We discussed these modes in a previous blog, Robot Collaborative Operation.

This post will go more deeply into the most commonly used mode: power & force limiting. Robots in this category include ones made by Universal Robots, as well as FANUC’s green robots and ABB’s Yumi.

What is power & force limiting?

Power & force limiting robots are designed with limited power and force, along with physical features to avoid or reduce injury or damage in case of contact. These robots are generally smaller, slower and less powerful than traditional robots but also more flexible and able to work near or with humans — assuming a risk assessment determines it is safe to do so.

The standards define the creation of a shared or collaborative work space for the robot and human, and define how they may interact in this space. In a power & force limiting application, the robot and operator can be in the shared/collaborative work space at the same time and there may be contact or collision between the operator and the collaborative robot system (which includes the robot, gripper/tool and work piece). Under the proper conditions the features built into the power & force limiting robot allow this close interaction and contact to occur without danger to the operator.

What technologies allow these robots to work closely with humans?

The limiting of the robot’s force can be implemented in several ways. Internal torque/feedback sensors in the joints, external sensors or “skins” and/or elastic joints are some of the methods robot suppliers use to assure low force or low impact. They also design possible contact areas to avoid injury or damage by using rounded edges, padding, large surface areas, etc. to soften contact. Grippers, tools and work pieces also need to be considered and designed to avoid injury or damage to people and equipment.

Peripherally, additional sensors in the robots, grippers, tools, work holders and surrounding work stations are critical parts of high performance robot applications. Connecting these sensors through protocols such as IO-Link and PROFISafe Over IO-Link allows more tightly integrated, better performing, and safer collaborative robot systems.

Where are power & force limiting robots typically applied?

Similar to traditional robots, power & force limiting robots are best applied in applications which are dull, dirty and/or dangerous (the 3 Ds of robotics). They are especially well suited to applications where the danger is ergonomic — repetitive tasks which cause strain on an operator. In many cases, power & force limiting robots are being applied to cooperate closely with people: the robots take on the repetitive tasks, while the humans take on the tasks which require more cognitive skills.

A large number of the customers for power & force limiting robots are small or medium-sized enterprises which can not afford the investment and time to implement a traditional robot, but find that power & force limiting robots fit within their budget and technical capabilities.

What are some of the benefits and drawbacks to power & force limiting robots?

Benefits:

  • Low cost
  • Fast, simple programming and set up; often does not require special knowledge or training
  • Small and lightweight
  • Easy to deploy and redeploy
  • Can be fenceless
  • Low power usage
  • Close human-robot interaction

Drawbacks:

  • Slow
  • Small payload
  • Low force
  • Low precision (not always the case, and improving)

Final Thoughts

Buying a power & force limiting robot does not necessarily mean that fences or other safeguards can be removed; a risk assessment must be completed in order to ensure the application is appropriately safeguarded. The benefits, however, can be significant, especially for smaller firms with limited resources. These firms will find that power & force limiting robots are very good at cost-effectively solving many of their dull, dirty and dangerous applications.

IO-Link devices deliver data specific to your manufacturing operations needs

IO-Link is a point-to-point communication standard [IEC61131-9]. It is basically a protocol for communicating information from end devices to the controller and back. The beauty of this protocol is that it does not require any specialized cabling. It uses the standard 3-pin sensor cable to communicate. Before IO-Link, each device needed a different cable and communication protocol. For example, measurement devices needed analog signals for communication and shielded cables; digital devices such as proximity sensors or photo eyes needed 2-pin/3-pin cables to communicate ON/OFF state; and any type of smart devices such as laser sensors needed both interfaces requiring multi-conductor cables. All of these requirements and communication was limited to signals.

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With IO-Link all the devices communicate over a standard 3-pin (some devices would require 4/5 pin depending if they need separate power for actuation). And, instead of communicating signals, all these devices are communicating data. This provides a tremendous amount of flexibility in designing the controls architectures for the next generation machines.

IO-Link data communication can be divided into 3 parts:

  1. Process data: This is the basic functionality of the sensor communicated over cyclical messages. For example, a measurement device communicating measurement values, not 4-20mA signals, but the engineering units of measurement.
  2. Parameter data: This is a cyclic messaging data communication and where IO-Link really shines. Manufacturers can add significant value to their sensors in this area. Parameter data is communicated only when the controller wants to make changes to the sensor. Examples of this include changing the engineering units of measurement from inches to millimeters or feet, or changing the operational mode of a photoelectric sensor from through-beam to retro-reflective, or even collecting capacitance value from a capacitive sensor. There is no specific parameter data governed by the consortium — consortium only focuses on how this data is communicated.
  3. Event data: This is where IO-Link helps out by troubleshooting and debugging issues. Event messages are generated by the sensor to inform the controller that something has changed or to convey critical information about the sensor itself. A good example would be when a photoeye lens gets cloudy or knocked out of alignment causing a significant decrease in the re-emitted light value and the sensor triggers an event indicating the probable failure. The other example is the sensor triggering an event to alert the control system of a high amperage spike or critical ambient temperatures. When to trigger these events can be scheduled through parameter data for that sensor.

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Each and every IO-Link device on the market offers different configurations and are ideally suited for various purposes in the plant. If inventory optimization is the goal of the plant, the buyer should look for features in the IO-Link device that can function in different modes of operation such as a photo eye that can operate as through-beam or retro-reflective. On the other hand, if machine condition monitoring is the objective, then he should opt for sensors that can offer vibration and ambient temperature information along with the primary function.

In short, IO-Link communication offers tremendous benefits to operations. With options like auto-parameterization and cable standardization, IO-Link is a maintenance-friendly standard delivering major benefits across manufacturing.

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Three Ways to Configure a Splitter and Harness the Power of Pin 2

Based on the increasing popularity of machine mounted I/O utilizing readily available IP67 components, it’s more important than ever to utilize every I/O point.  I/O density has increased over the years and the types of I/O have become more diversified, yet in many systems pin 2 is left unused by the end user.  Sensors tend to come in twos, for example, a pneumatic cylinder may require a sensor for the extended position and one for the retracted position.  Running each individual sensor back to the interface block utilizes pins 1,3 and 4 (for power, ground and signal) but wastes pin 2 on each port.

Figure 1
Fig. 1 Bad I/O configuration: neglecting pin 2 is inefficient and costly

Rather than using a separate port on the I/O block for each sensor, a splitter can collect the outputs of two sensors and deliver the input to a single port.  With a splitter, one sensor output goes to pin 4, the other goes to pin 2.

By putting two signals into one and utilizing both pins 2 and 4, the overall I/O point cost decreases.

There are multiple ways to configure a splitter to utilize pin 2. We will review three methods — good, better and best:

1. T-splitter on the I/O block:

Figure 3
Fig. 3 Good basic method for utilizing the additional I/O point, pin-2

A T-splitter is a good way to utilize pin 2.  However, the “T” covers the I/O module port eliminating the benefit of the high-value diagnostic LEDs on the block. Also, individual cables must run all the way from the block to the sensors at the installation point, creating clutter and cable bulk.  In addition, when Ts are used on a vertically mounted block, the extra cable bulk can weigh down the T-splitter and threaten its integrity.

2. V-type splitter on the I/O block:

Figure 4
Fig. 4 Better way of utilizing pin 2 while also allowing visibility of diagnostic LEDs

The use of a V-type configuration allows better visibility of the diagnostic LEDs and eliminates the need to purchase a separate part. However, individual cables must still be run from the block to the sensors, creating clutter and cable bulk.

3. Ytype configuration:

Figure 5
Fig. 5 Best way to utilize pin 2

In the Y-type splitter configuration, all aspects of usability are improved. One cable runs from the I/O block to the installation point. The split of pins 2 and 4 is done as close to the sensors as possible. This significantly cleans up cable clutter, provides a completely unrestricted view of the diagnostic LEDs and allows for easy installation of multiple connectors to the I/O block.

How IO-Link is Revolutionizing Overall Equipment Efficiency

Zero downtime.  This is the mantra of the food and beverage manufacturer today.  The need to operate machinery at its fullest potential and then increase the machines’ capability is where the demands of food and beverage manufacturers is at today.  This demand is being driven by smaller purchase orders and production runs due to e-commerce ordering, package size variations and the need for manufacturers to be more competitive by being flexible.

Using the latest technology, like IO-Link, allows manufacturers to meet those demands and improve their Overall Equipment Efficiency (OEE) or the percentage of manufacturing time that is truly productive.  OEE has three components:

  1. Availability Loss
    1. Unplanned Stops/Downtime – Machine Failure
    2. Planned Downtime – Set up and AdjustmentsS
  2. Performance Loss
    1. Small Stops – Idling and Minor Stops
    2. Slow Cycles – Reduced Speed
  3. Quality Loss
    1. Production Rejects – Process Defects
    2. Startup Rejects – Reduced Yield

IO-Link is a smart, easy and universal way to connect devices into your controls network.

The advantage of IO-Link is that it allows you to connect to EtherNet/IP, CC-Link & CC-LinkIE Field, Profinet & Profibus and EtherCAT & TCP/IP regardless of the brand of PLC.  IO-Link also allows you to connect analog devices by eliminating traditional analog wiring and provides values in actual engineering units without scaling back at the PLC processor.

Being smart, easy and universal, IO-Link helps simplify controls architecture and provides visibility down to the sensor and device.

IO-Link communicates the following:

  • Process data (Control, cyclical communication of process status)
  • Parameter data (Configuration, messaging data with configuration information)
  • Event data (Diagnostics, Communication from device to master (diagnostics/errors )

This makes it the backbone of the Smart Factory as shown in the graphic below.

 

IO-Link Simplifies the Controls Architecture

IO-Link OEE1

IO-Link OEE2