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We get technical
Industrial Robotics | Volume 6
Industrial robots and their human counterparts
How sensor fusion enables AMRs to maneuver around factory floors efficiently How delta robotics optimize and streamline electronics manufacturing processes Use compact industrial robots to make any shop more productive
we get technical
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Industrial robots and their human counterparts
What are the key factors used to classify industrial robots?
What are the important considerations when assessing cobot safety?
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Safely and efficiently integrating amrs into industry 4.0 Operations for maximum benefit
How sensor fusion enables AMRs to maneuver around factory floors efficiently
Robotics in today’s automotive manufacturing
How delta robotics optimize and streamline electronics manufacturing processes
How SCARA, six-axis, and cartesian pick-and-place robotics optimize and streamline electronics manufacturing processes
Use compact industrial robots to make any shop more productive
Fundamentals of pneumatic grippers for industrial applications
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Editor’s note Today’s manufacturing landscape is filled with obstacles and difficult choices. While facing the biggest workforce shortage in our lifetime, manufacturers also have to compete against low-cost labor markets all while trying to meet an ever-rising customer demand. One way to combat this is through automation. The benefits of adopting automation into their business model allows them to locate in more business-friendly environments. Industrial Robotics have been in the industry for decades, but new on the scene are Cobots (Collaborative Robotics). These new cobots are able to work side by side with their human counterparts. They provide humans with the ability to focus on more mentally challenging tasks while the cobot handles the more tedious/ menial tasks. This new partnership of man and machine means greater accuracy, more efficiency, less waste and higher throughput. In this magazine, we will discuss the various types of industrial robots, fundamentals of robots, AMRs, and much more.
Industrial robots and their human counterparts
By Eric Halvorson Marketing Technology Manager, Automation & Control
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The conversation around robots and their use in manufacturing has long been controversial. Many fear that the introduction of robots into the workplace will displace human jobs. In some respects, yes, robots will replace some jobs, but it’s not that simple. Yes, robots will replace some lower-level jobs. These jobs are the more menial and tedious jobs. These are jobs such as quality control on a factory line. Some
illness, and complacency. Robots and machines do not. But the question is what happens to those employees after their jobs are made obsolete? This is where the employee benefits. Now, those same employees who were being underutilized in the past can move into better quality jobs, including jobs that require problem solving or jobs that require more job fulfillment. These are higher quality jobs. Many of these jobs
People have off-days and are subject to fatigue, illness, and complacency. Robots and machines do not.
of us can recall the opening scene of “Laverne and Shirley” in Shotz Brewery. While their antics are funny and over the top, in today’s manufacturing world, the demands for quality are quite high. The need to ensure those bottles are properly filled and meet customer expectations is more important than ever. With the use of robotics and machine vision, we can now inspect every bottle as it passes at break-neck speed. From ensuring the liquid is filled to the proper level and color accuracy to checking labeling applications and cap being seated correctly, all aspects of the product’s quality are checked and made to meet specific tolerances. People have off-days and are subject to fatigue,
are in concert with robotics. These are called collaborative robots or cobots for short. As I said earlier, there is quite a bit of fear about the implementation of cobots in the workplace. Yes, some jobs will be made obsolete. But what many will experience is a shift in their job roles. There will be a need for robot designers, programmers, and maintenance workers. Others will need to be upskilled; basically, they will need to get an upgrade in their skillset. This means better pay, better benefits, and greater job satisfaction. There are also things that humans are inherently good at, where their robot counterparts are not, such as problem-solving skills, critical thinking, and creativity.
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Industrial robots and their human counterparts
Cobots have come a long way over the past decade. With safety in mind, these robots work right alongside their human counterparts. These cobots are capable of handling the heavy lifting for humans, allowing them to focus on the more mental workload. For example, at Amazon, cobots are used to move product to pickers rather than the picker going to the shelf, pulling the product, and returning to their station. This saves the worker time, steps, and possibly a lot of heavy lifting. The cobot saves the worker’s energy and reduces the wear and tear on their bodies daily.
But how do we ensure human safety around cobots? Great question. Today’s safety standards for cobots are exceptionally stringent, as they should be. There are numerous safety features on cobots as defined by ISO/TS 15066, which provides guidelines for the design and implementation of collaborative workspaces.
This enables shop managers and manufacturers to safely
incorporate cobots into overlapping workspaces between humans and their mechanical counterparts. Some examples: ■ Maximum Allowable Speed. This is set at the point of the EOAT (End-of-arm-tooling).
Cobots have come a long way over the past decade. With safety in mind, these robots work right alongside their human counterparts
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These speeds are inline with human equivalent speeds. ■ Speed and Separation Monitoring. Defines the minimum safety distance between the worker and the robot system to prevent contact between the robot and the human. This can be achieved utilizing safety scanners, light curtains, and operator presence mats. ■ Power, Force, and Torque Limits. Cobots are designed to measure torque at every joint in case of excessive torques or forces, and monitors for sudden impacts, including soft obstructions. ■ Redundant Checking Systems Diagnostics. If the robot detects an anomaly or error at any point, the robot will disable motor power instantly. ■ Safety Rated Stop Modes. Cobots are required to act based on the level of risk. That could be a full emergency stop if a safety mishap has occurred, or it may be a protective stop if a human has entered its operating area. ■ Ergonomic Design. In six axis robots, there are a number of potential pinch points. By designing those joints ergonomically, the worker can avoid injury should their hand, fingers, or even loose clothing get trapped in a joint. With the installation of any robot in a production setting, great care must be taken to ensure a truly safe workspace. This is particularly true in an overlapping workspace that will be shared by humans and their robot counterparts. Consulting a professional installer or integrator will help you to do a full risk assessment and ensure you meet all applicable safety codes and regulations with regards to cobots. Cobots have the ability to reduce worker fatigue, increase production rates, and increase quality, all while reducing waste. In truth, they can be a force multiplier for your production force. In today’s world where we all face labor shortages, increased competition, and high consumer demand, cobots can be an equalizer while creating higher quality jobs.
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What are the key factors used to classify industrial robots?
By Jeff Shepard Contributed By DigiKey's North American Editors
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Millions of industrial robots are active in Industry 4.0 factories around the world. They are used to increase production rates, improve quality, reduce costs, and support more flexible and sustainable operations. Because of the importance of industrial robots, the International Organization for Standardization (ISO) developed standard 8373:2021, Robotics Vocabulary, to define terms used in robotics and provide a common language for discussing the many types of robots and their applications. The International Federation of Robots (IFR) used key terms defined in ISO 8373:2021 to identify six robot classifications based on their mechanical structure, including: ■ Articulated
ISO 8373:2021 defines an industrial robot as an "automatically controlled, reprogrammable, multipurpose manipulator, programmable in three or more axes, which can be either fixed in place or fixed to a mobile platform for use in automation applications in an industrial environment." Reprogrammability is a crucial differentiator. Some industrial machines may have manipulators and move in multiple axes that can handle specific tasks like picking up bottles on a beverage filling line and placing them into a box. But it's not a robot if it's dedicated to that single purpose and not reprogrammable. "Reprogrammable" is defined in ISO 8373 as "designed so that the programmed motions or auxiliary functions may be changed without physical alterations."
■ Cartesian ■ Cylindrical ■ Parallel/Delta ■ Polar ■ SCARA
Types and numbers of robot joints
ISO 8373 defines two types of robot joints: ■ Prismatic joint, or sliding joint, is an assembly between two links that enables one to have a linear motion relative to the other. ■ Rotary joint, or revolute joint, is an assembly connecting two links that enables one to rotate relative to the other about a fixed axis. The IFR has used these and other ISO 8373 definitions to identify six industrial robot classifications
This article reviews ISO 8373:2021, looking at the four key terms that define a robot, focusing on the need for reprogrammability and the types and numbers of robot joints used by the IFR to develop robot classifications. It then digs into the details and nuances of each robot classification and presents exemplary robots from several makers. Along the way, it also looks at systems called robots that don't meet all the ISO requirements.
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What are the key factors used to classify industrial robots?
based on their mechanical structure or topology. In addition, different robot topologies have different numbers of axes and, therefore, different numbers of joints. The number of axes is a key characteristic of industrial robots. The number of axes and their types determines the robot's range of motion. Each axis represents an independent motion or degree of freedom. More degrees of freedom result in a robot being able to move through larger and more complex spaces. Some robot types have a fixed number of degrees of freedom, while others can have different numbers of degrees of freedom. End effectors, also called end-of- arm tooling (EOAT) or "multipurpose manipulators" in ISO 8373, are another important element in most robots. There's a wide range of end effectors, including grippers, dedicated process tools like screwdrivers, paint sprayers, or welders, and sensors, including cameras. They can be pneumatic, electric, or hydraulic. Some end effectors can rotate, giving the robot another degree of freedom. The following sections begin with the IFR definition for each robot topology and then examine their capabilities and applications. Articulated robots have three or more rotary joints.
This is a large class of robots. Articulated robots can have ten or more axes, with six being the most common. Six-axis robots can move in x, y, and z planes and pitch, yaw, and roll rotations, enabling them to mimic the movement of a human arm. They are also available with a wide range of payload capacities from under 1 kg to over 200 kg. The reach capabilities of these robots also vary widely from under 1 meter to multiple meters. For example, the KR 10 R1100-2 from KUKA is a six-axis articulated robot with a maximum reach of 1,101 mm, a maximum payload of 10.9 kg, and a pose repeatability of ±0.02 mm (Figure 1). It also features high-speed movements, short cycle times, and an integrated energy supply system. Articulated robots can be permanently mounted on the floor, wall, or ceiling. They can also be mounted on tracks on the floor or overhead, on top of an autonomous mobile robot or other movable platform, and moved between workstations. They are used for various tasks, including material handling, welding, painting, and inspection. Articulated robots are the most common topology for implementing collaborative robots (cobots) designed to work with humans. While a conventional robot operates in a safety cage
with safety barriers, a cobot is designed for close interaction with people. For example, the LXMRL12S0000 cobot from Schneider Electric has a maximum reach of 1,327 mm, a maximum payload of 12 kg, and a pose repeatability of ±0.03 mm. Cobots often feature collision protection, rounded edges, force limits, and lighter weight for enhanced safety.
Figure 1: Six-axis articulated robot with a pose repeatability of ±0.02 mm. (Image source: DigiKey)
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Cartesian robot (sometimes called a rectangular robot, linear robot, or gantry robot) has a manipulator with three prismatic joints whose axes form a Cartesian coordinate system. Modified Cartesian robots are available with two prismatic joints. Still, they don't meet the ISO 8373 requirement that they must be "programmable in three or more axes" and so aren't technically robots. There's more than one way to configure three prismatic joints and, therefore, more than one way to configure a Cartesian robot. In a basic Cartesian topology, all three joints are at right angles, with one moving in the x-axis, attached to a second one moving in the y-axis, that's attached to a third one moving in the z-axis. Although often used as a synonym for a Cartesian robot, the gantry topology is not identical. Like a basic Cartesian, gantry robots
support linear motions in three- dimensional space. But gantry robots are configured with two base x-axis rails, a supported y-axis rail spanning the two x axes, and a cantilevered z-axis attached to the y-axis. For example, the DLE-RG- 0012-AC-800-800-500, from Igus, is a gantry robot with an 800 mm x 800 mm x 500 mm work area that
can carry up to 5 kg and move at up to 1.0 m/s with a repeatability of ±0.5 mm (Figure 2). Cylindrical robot has a manipulator with at least one rotary joint and at least one prismatic joint, whose axes form a cylindrical coordinate system.
Figure 2: Gantry robot with an 800 mm x 800 mm x 500 mm workspace. (Image source: Igus)
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What are the key factors used to classify industrial robots?
Cylindrical robots are relatively simple and compact, and their limited range of motion makes them easy to program. They are less common than their more complex cousins. Still, they are especially suited for applications like grinding processes, palletizing, welding (especially spot welding), and material handling, for example, loading and unloading semiconductor wafers into cassettes in an integrated circuit fabrication operation (Figure 3). Cylindrical robots typically move at speeds of 1 to 10 m/s, and they can be designed to carry heavy loads. Applications for
cylindrical robots can be found in automotive, pharmaceutical, food and beverage, aerospace, electronics, and other industries. Parallel/Delta robot i s a manipulator whose arms have links that form a closed loop structure. While other robots, like cylindrical or Cartesian topologies, are named after their motion, the delta robot is named for its upside-down triangular shape. Delta robots have 2 to 6 axes, with 2- and 3-axis designs being the most common. Like 2-axis Cartesian robots, 2-axis delta robots don't technically meet the requirements of ISO 8373 to be called robots. Delta robots are designed for speed rather than strength. They are mounted above the work area and perform functions like pick- and-place, sorting, disassembly, and packaging. They are often found above a conveyor, moving parts down a production line. The gripper is connected to long, slender mechanical linkages. These linkages lead to three or four large motors at the robot's base. The other end of the linkages is attached to a tooling plate where the EOAT attaches. The RBTX-IGUS-0047 from Igus is an example of a 3-axis delta robot. It has a working space diameter of 660 mm and can handle a maximum load of 5 kg. When handling a load of 0.5 kg, it
can perform 30 picks per minute move with a maximum speed of 0.7 m/s and an acceleration of 2 m/s2. It has a repeatability of ±0.5 mm (Figure 4).
Figure 4: Three-axis delta robot and controller (left). (Image source: DigiKey)
Polar robot (spherical robot) is a manipulator with two rotary joints and one prismatic joint, whose axes form a polar coordinate system. One of the rotary joints enables a polar robot to rotate around the vertical axis that extends up from the base. The second rotary joint is at right angles to the first rotary joint and enables the robot arm to swing up and down. Finally, the prismatic joint enables the robot arm to extend or retract from the vertical axis.
Figure 3: This cylindrical robot has one rotary and prismatic joint. (Image source: Association for Advancing Automation)
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Polar robots, while simple in construction, have drawbacks that limit their use compared with other topologies like articulated, Cartesian, and SCARA robots: ■ The spherical coordinate system makes programming more complex. ■ They typically have a more limited payload capacity than other types of robots. ■ They are slower than other robots. The main benefits of polar robots include a large workspace and high precision. They are used for machine tool tending, assembly operations, material handling in automotive assembly lines, and gas and arc welding. SCARA robot (from "selectively compliant arm for robotic assemblies") is a manipulator with two parallel rotary joints to provide compliance in a selected plane. A basic SCARA robot has three degrees of freedom, the third from a rotating end effector. SCARA robots are also available with an additional rotary joint for a total of four degrees of freedom, enabling more complex motions. SCARA robots are often used in pick-and-place or assembly applications where high speed and high accuracy are needed. For example, Dobot's M1-PRO is a 4-axis SCARA robot with a working radius of 400 mm, a maximum
payload of 1.5 kg, and a repeatability of ±0.02 mm. It has sensor-free collision detection and drag-to- teach programming, making it suitable for use as a cobot as well as a standalone robot (Figure 5).
Figure 5: Four-axis SCARA robot with a repeatability of ±0.02 mm. (Image source: DigiKey)
Conclusion All industrial robots meet the ISO 8373 requirement to be automatically controlled with a reprogrammable, multipurpose manipulator. However, not every design has a defined number of axes for a specified topology. Delta and Cartesian robots are available with fewer than the defined number of axes, while some SCARA robots have more axes than defined by IFR.
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What are the important considerations when assessing cobot safety?
Collaborative robots (cobots) are designed to work with humans and support flexible production in Industry 4.0 factories. Compared with traditional industrial robots, cobots are simpler, easier to set up, and don't require safely isolated workspaces. Because they are designed to work with people, cobots are built differently than other industrial robots, including features like collision detection systems, force feedback, elastic actuators, and low-inertia servo motors.
By Jeff Shepard Contributed By DigiKey's North American Editors
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Since they are different by design, specific safety standards have been developed for cobots. The International Organization for Standardization Technical Specification (ISO/TS) 15066 specifies safety requirements for industrial cobots and their work environments. It supplements the requirements and guidance on cobot operation in ISO 10218‑1 and ISO 10218‑2. This article briefly reviews the requirements of ISO/TS 15066 and how they fit in with ISO 10218- 1 and 10218-2. It then considers the complexities of collaboration, including how the collaborative workspace is defined. It examines factors related to robot safety, like safety features built into cobots, and what external safety functions are needed, along with exemplary devices like proximity sensors, light curtains, and safety contact mats. It closes with a brief review of a few applications specific to cobot safety considerations. There are several key safety standards for industrial robots and cobots. ISO/TS 15066 details safety requirements for industrial cobot systems and the work environment and was written to build on and supplement the limited requirements in previous standards like the ISO 10218 series. ISO 10218-1 focuses on general robots and robotic devices, while ISO 10218-2
focuses on robot systems and integration. American National Standards Institute/Robotics Industry Association (ANSI/RIA) R15.06 is a national adoption of ISO 10218-1 and ISO 10218-2.
Common protective features integrated into cobots include contact detection systems based on torque measurements at every joint that monitor for unexpected impacts, obstructions, or excessive forces or torque. There should also be automatic braking systems and manual brake releases for moving the arm without power. Unexpected contact with the person by the cobot is a particular concern. The standards dictate that contact should be prevented anywhere on a person's head. In addition, the standard splits the body into 29 specific areas and details limitations for two types of contact: ■ Transient contact is a moving, dynamic event where the cobot hits a person. Limitations are based on location, inertia, and relative speed. ■ Quasi-static contact occurs when a body part is trapped between the cobot and a surface. Limitations are based on pressure and force related to crushing and clamping effects. The specification provides guidance, not absolute limits, based on application considerations. It also states that the guidance is informative and reflects current best practices since collaboration between people and robots is a new field, and research is ongoing.
Complexities of collaboration
Before getting into the details of cobot safety, it's helpful to define collaboration. Collaboration in robotics is complex and includes three factors: ■ A cobot is a "robot designed for direct interaction with a human within a defined collaborative workspace," according to ANSI/ RIA R15.06. ■ A collaborative operation is a "state in which a purposely designed robot system and an operator work within a collaborative workspace," according to ISO/TS 15066. ■ Finally, a collaborative workspace is the "workspace within the safeguarded space where the robot and a human can perform tasks simultaneously during production operation," according to ANSI/RIA R15.06. It comes down to the definition of the collaborative workspace "within the safeguarded space." The safeguarded space includes a layer of safety protection in addition to the standard safety functions included in the cobot.
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What are the important considerations when assessing cobot safety?
reducing the hazards and risks associated with the application. ISO 10218 includes a list of safety features that can be appropriate in various circumstances but no definitive requirements. ISO/TS 15066 brings additional details to cobot risk assessments. In each case, the goal of the risk assessment is to identify external safety devices and systems needed to ensure the safe implementation of collaborative applications. For a deeper dive into risk assessment and robots, see the article "Safely and Efficiently Integrating AMRs into Industry 4.0 Operations for Maximum Benefit."
Continuum of collaboration There is no single collaborative application. People and cobots can interact and collaborate in a continuum of ways. Collaborative applications range from co- existence, where a robot stops under power when a person enters the collaborative workspace, to an interactive activity with the person touching the cobot while in operation (Figure 1). A risk assessment is required to identify the safety needs of individual collaborative applications. It includes identifying, evaluating, and
Protection and efficiency
While cobots are designed for safe operation, additional protection layers can improve collaborative applications' efficiency. Without additional safety, when a person enters the collaborative workspace, ISO/TS 15066 mandates a maximum speed of 0.25 meters per second (m/s) per axis. For most cobots, that's very slow. For example, the LXMRL12S0000 Lexium cobot from Schneider Electric has a maximum payload of 12 kilograms (kg), an operating radius (working range) of 1327 millimeters (mm), positioning
Figure 1: Human and robot collaboration includes a broad range of possible levels of interaction. (Image source: SICK)
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accuracy of ±0.03 mm, and a maximum speed of the tool end of 3 meters per second (m/s), 12 times faster than the maximum allowed by ISO/TS 15066 when a person is in the collaborative workspace (Figure 2).
In many applications, the cobot can be operating alone for long periods. So, sensing the presence or absence of people in the collaborative workspace can enable much faster operation and higher efficiency when no one is present. Common devices for sensing the presence of people include safety scanners, light curtains, and safety contact floor mats. Each technology offers a different set of benefits, and they are often used in combination. Safety scanners Safety scanners monitor a designated area to detect the presence of people. They can determine how far away a person is and implement various warning zones in addition to the active safety zone. Omron's model OS32C-SP1-4M is a good example of a safety laser scanner designed for use with cobots. It has a safety radius of up to 4 meters (m) and can support multiple warning zones up to 15 m. It includes 70 standard sets of safety zone and warning zone combinations to support complicated collaborative workspaces. In addition, the minimum object resolution can be set to 30, 40, 50, or 70 mm, and the response time can range from 80 milliseconds (ms) up to 680 ms, further increasing application flexibility (Figure 3).
Figure 3: This safety scanner has a safety radius of up to 4 m and can support multiple warning zones up to 15 m. (Image source: DigiKey)
Light curtains Light curtains can measure the presence of people and can be designed to detect objects of various sizes, like fingers or hands. Unlike safety scanners, light curtains don't measure distance. They send a series of light beams between linear emitter and receiver arrays and can sense when an object breaks one or more beams. In terms of safety ratings, there are two primary light curtain classifications: Type 2 and Type 4. They have similar outward appearances but are designed to provide different levels of safety. Type 4 monitors the safeguarded space that defines a collaborative workspace. Type 2 light curtains are designed for lower-risk applications.
Figure 2: This cobot can move 12 times faster than the maximum allowed by ISO/TS 15066 when a person is in the collaborative workspace. (Image source: Schneider Electric)
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What are the important considerations when assessing cobot safety?
Light curtains guard perimeters and are available with several levels of resolution, like 14 millimeters (mm) for finger detection and 24 mm for hand detection. The model, SLC4P24-160P44 from Banner Engineering , is a Type 4 light curtain kit with an emitter and receiver array and has a resolution of 24 mm to protect people and machines like cobots (Figure 4). The emitters have a row of synchronized modulated infrared light-emitting diodes.
Receivers have a corresponding row of synchronized photodetectors. The emitters have a 2-meter range, and these light curtains can be installed in lengths from 160 to 320 mm in 80 mm increments. Safety laser scanners and light curtains provide non-contact means for enhancing the safety of collaborative workspaces. However, they can be difficult to use in optically challenging environments
like areas with highly reflective surfaces that can send unwanted light interference, and they can trip because of leaking oil or grease or excessive dust or humidity. Some of these optical sensors include sensitivity adjustments that can help mitigate certain types of interference. Those sensitivity adjustments can also increase response times and other performance compromises. Another solution is to use a safety contact mat together with optical sensing devices.
Figure 4: This Type 4 light curtain has a resolution of 24 mm. (Image source: Banner Engineering)
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application lie on the continuum of collaboration (see Figure 1)? The closer the interaction between the cobot and people, the more safeguarding is needed. There are more details to consider. Some of them include:
Safety contact mats
Conclusion
Safety contact mats have two conductive plates separated by a rasterized insulating layer and can be used alone or in combination with other types of sensors. If a person steps on the mat, the top conductive plate is depressed and contacts the lower plate, triggering an alert signal (Figure 5). The exterior of the mats is a polyurethane material that's slip-resistant and impervious to water, dirt, and oil. The SENTIR mat model 1602-5533 from ASO Safety Solutions can connect up to 10 mats in series to a single monitoring unit for a maximum coverage of 10 m 2 .
Cobot safety is complex. It begins with defining the collaborative workspace within the safeguarded space and requires a risk assessment of the collaborative operation. Standards like ISO/ TS 15066 and the ISO 10218 series are important and provide recommendations and guidelines. Cobots include basic safety features like collision detection systems, force feedback, elastic actuators, and low-inertia servo motors. Depending on the specifics of the collaborative application, additional safety devices like proximity sensors, light curtains, and safety contact mats may be needed.
■ Each location needs to undergo a detailed risk assessment to see if the
cobot has been moved from workstation to workstation. Even if they appear to be the same, small variations can make a difference in safety. ■ If other machines are in the collaborative workspace, do they need to be linked to the shutdown system or the safety slowdown for the cobot? ■ This article has focused on safety-related hardware, but for networked systems that are increasingly common, cybersecurity is an important consideration to prevent interference with cobot operation or the safety systems.
Safety is in the details
There is no single formula that guarantees safety. Every collaborative application is different and needs to be handled based on its unique characteristics and needs. A key factor is: where does the
Figure 5: When stepped on, the safety mat's top and bottom conductive layers make contact, triggering an alert signal. (Image source: ASO Safety Solutions)
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Safely and efficiently integrating AMRs into industry 4.0 operations for maximum benefit
By Jeff Shepard Contributed By DigiKey's North American Editors
In response to the surging use of autonomous mobile robots (AMRs), also called industrial mobile robots, in Industry 4.0 operations, the Association for Advancing Automation (A3), together with the American National Standards Institute (ANSI), recently released the second increment of its safety standard for AMRs: ANSI/ A3 R15.08-2, which details the requirements for integrating, configuring, and customizing an AMR or fleet of AMRs into a site. An essential requirement is the performance of a risk assessment per ANSI/ISO 12100 or ANSI B11.0. The new standard complements the previously released R15.08-1 that focused on the safe design and integration of AMRs.
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The R15.08 series of standards builds on the earlier ANSI/ Industrial Truck Standards Development Foundation (ITSDF) B56.5 safety standard for automated guided industrial vehicles (AGVs). The newer standard recognizes three classes of AMRs based on the inclusion of specific functions and features. This article briefly compares AMRs and AGVs and ANSI/ITSDF B56.5 and International Standards Organization (ISO) 3691-4 versus ANSI/A3 R15.08. It then reviews the risk assessment strategies outlined in ANSI/International Standards Organization (ISO) 12100 and ANSI B11.0, how they relate to AMRs, and how they are integrated into R15.08-2. Next, it reviews the three classes of AMRs defined in R15.08-2 before closing with a presentation of practical considerations for AMR integration, including how to implement mapping and commissioning, how to manage fleets of AMRs, and how to navigate new opportunities for virtual commissioning using simulation and digital twins using examples from Omron Automation and Siemens. AGVs can travel only along a predetermined and marked path. They have no independent navigation capabilities. They stop if they arrive at an obstacle and wait for it to be removed before proceeding along the fixed path. AMRs include independent
Figure 1: AMRs (left) navigate around obstacles while AGVs (right) stop when they arrive at an obstacle. (Image source: Omron)
navigation systems and can change paths and move around obstacles (Figure 1). Because of these differences, AGVs are better suited for relatively stable and unchanging environments, while AMRs support more flexible and scalable deployments like those needed in Industry 4.0 operations.
subsequently applied to AMRs without modification. The newer ISO 3691-4 standard covers AGVs and has sections dedicated to AMRs. ANSI/ITSDF B56.5 is a Safety Standard for Guided Industrial Vehicles, unmanned guided industrial vehicles, and the automated functions of manned industrial vehicles; it does not cover AMRs. The newer ANSI/ RIA R15.08 is a safety standard for the use of AMRs in industrial environments. It’s based on and expanded from the R15.06
Standard evolution
Some AMR standards have evolved from previously developed standards for AGVs and stationary robots. For example, EN 1525:1997 was developed for AGVs and was
standard for safely using stationary robotic arms.
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Safely and efficiently integrating AMRs into industry 4.0 operations for maximum benefit
Another important standard is EN ISO 13849, which defines the safety performance levels (PLs) for various types of equipment. There are five levels, from PLa to PLe, with increasingly stringent requirements. AGV and AMR makers must reach PLd safety that ensures continuous safe operation in the event of a single fault, i.e., by using redundant systems. ANSI/A3 R15.08-2 requires a risk assessment for integrating and deploying AMRs. The risk assessments defined by ISO 12100 and ANSI B11.0-2010 are very similar, though not identical.
Next is risk estimation, which looks at the likely severity of harm from each hazard and the probability of its occurrence. A very severe hazard with a low likelihood of occurrence may receive a similar ranking as a hazard with a less severe outcome that’s more likely to occur. All identified risks are evaluated and ranked to prioritize risk reduction efforts. Risk assessment can be an iterative process, identifying the most severe risks and reducing their probability of occurrence and/or the severity of their outcome until an acceptable level of residual risk has been achieved (Figure 2).
AMR classes
R15.08 recognizes three types of AMRs: Type A: AMR platform only. In contrast with AGVs, type A AMRs can function as independent systems without requiring environmental changes. They can include optional features like a battery management system, the ability to independently locate a charger and recharge its battery, the ability to integrate with centralized fleet management software, etc. Type A AMRs are most often used to move materials around a factory or warehouse. Type B: A type A AMR with the addition of a passive or active attachment that is not a manipulator (Figure 3). Typical attachments include conveyors, roller tables, fixed or removable totes, lifting devices, vision systems, weighing stations, etc. Type B AMRs can be used for more complex logistics tasks. Vision systems can be used for product inspections and identification, weighing (or estimating the number of) parts, and so on.
ISO 12100 targets original equipment manufacturers,
whereas ANSI B11.0 focuses more on machinery and end-user safety. The basics of risk assessment are similar for both standards. Risk assessment A risk assessment is a highly structured analysis to arrive at an acceptable level of risk. It recognizes that no system or environment is perfect; inherent risks can be managed but not eliminated. It begins by determining the limits of the machine’s operation and identifies hazards that can arise if the machine operates near or outside of those limits.
Figure 2: Key components of a risk assessment include risk analysis, evaluation, and reduction. (Image source: SICK)
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Figure 3: Type B AMR with a roller table attachment. This also shows typical navigation and safety systems common to all three types of AMRs. (Image source: Omron)
Type C: A type A AMR with the addition of a manipulator. The manipulator can be a robotic arm with three or more axes of movement. Type C AMRs can be designed to function as collaborative robots (cobots) working alongside humans. They can also be machine attendants, perform pick and place operations, complete complex inspection tasks, do harvesting and weeding in agricultural settings, etc. Some designs can move from place to place and perform different tasks at each station. Commissioning, mapping, and following the lights All three types of AMRs are designed to simplify deployment. Compared with AGVs that
require extensive infrastructure installation, no construction is necessary for AMR deployment, and programming needs can be minimal. Basic commissioning is a four-step process (Figure 4): ■ The AMR is delivered with all the needed software installed; the first task is to install and charge the battery. ■ Mapping is critical and can be manually or automatically implemented. For manual mapping, a technician controls the AMR and takes it around the facility so it can learn about the environment. Laser-guided AMRs can automatically scan up to 1,000 square feet per minute to create maps capturing all the features in the immediate area and wirelessly send the resulting map to a central
computer. In both cases, maps can be customized with virtual routes and forbidden lines for safe operations and can be shared across fleets of AMRs. ■ Setting goals includes the identification of pick-up and drop-off locations. ■ Task assignment is the final step and includes scheduling and coordination of the various AMRs in the fleet and integration with Enterprise Resource Planning (ERP), the Manufacturing Execution System (MES), and the Warehouse Management System (WMS).
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Safely and efficiently integrating AMRs into industry 4.0 operations for maximum benefit
Figure 4: AMRs are delivered with complete software installed and can be quickly commissioned and integrated into a production environment. (Image source: Omron)
Traffic management includes scheduling pick-up and drop-off locations and times for maximum efficiency and notifying robots of destination changes or new obstacles, enabling them to recalculate their path for maximum efficiency and safety. Charge management tracks the battery charge level of each robot in the fleet, enabling proactive charging and maximum uptime. Coordinated software updates across the fleet to ensure the latest version is available for each type of robot.
In addition to mapping a facility using laser scanning, some Omron AMRs use a camera to detect and plot the location of overhead lights. It creates and overlays a “light map” with the standard “floor map.” Laser localization can tolerate changing environments on the floor up to a point. Suppose over 80% of the features change, for example, on a shipping dock where pallets or rolling carts constantly change location. In that case, laser localization is less useful, and adding the light map increases the reliability of navigation. Using the light map also enables AMRs to more easily navigate across wide- open areas in large facilities.
Managing robot fleets Effective management of robot fleets can multiply the benefits of using AMRs. It can support centralized control and coordinated operation of mixed types of AMRs and provide the data and analytics needed to maximize operational efficiencies. Some common features of AMR fleet management systems include: Optimized task assignments are based on the capabilities of each robot in the fleet, their current locations, and anticipation of where their next assignment will be located.
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Enterprise integration connects the fleet management software to ERP, MES, and WMS systems so jobs can be allocated and scheduled automatically to the fleet in real-time. Virtual commissioning A combination of digital twins and simulation software enables virtual commissioning. In this case, a digital twin is a virtual representation of an AMR. Digital twins can be used to virtually validate the performance of individual AMRs and fleets of AMRs. Virtual commissioning uses robotics simulation software to combine the digital twins of AMRs with a digital twin of the surrounding environment (Figure 5). AMR virtual commissioning can also be used to integrate and coordinate the operation of robots from several manufacturers. During the virtual commissioning process, engineers can quickly and efficiently create multiple scenarios to verify the proper functioning of the entire system, not just isolated AMRs. Virtual safety testing and debugging can also be implemented with digital twins and simulation. Virtual AMRs can be subjected to anomalous situations to test various contingencies and ensure the proper functioning of safety protocols.
Figure 5: AMR digital twins can be virtually inserted into a simulated factory environment for virtual commissioning. (Image source: Siemens)
configuring, and customizing an AMR or AMR fleet into a site. A risk assessment performance is a key requirement within the new standards in accordance with ANSI and ISO standards. The tools for AMR commissioning are also evolving with the emergence of virtual commissioning using digital twins and simulation. This was the first of a two- part series and focused on the implications of the recently released R15.08-2 standard regarding safety, risk assessment, and commissioning of AMRs. The second article is written in anticipation of R15.08-3, which is currently under development and will address the topic of sensor fusion in AMRs.
The ability to implement virtual debugging can speed up the deployment of AMR fleets. Debugging fleets of physical AMRs after deployment is challenging and time-consuming. It involves work stoppages and negatively impacts the productivity of the facility. There are no work stoppages with virtual debugging, and users are assured that the AMRs will perform as expected in the real world.
Conclusion
AMR deployments are becoming increasingly prevalent in a wide range of Industry 4.0 installations. The standards landscape for AMRs is evolving to address requirements for safely and efficiently integrating,
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How sensor fusion enables AMRs to maneuver around factory floors efficiently
By Jeff Shepard Contributed By DigiKey's North American Editors
With increasing instances of people and autonomous mobile robots (AMRs), also called industrial mobile robots (IMRs), working in the same area, multiple inherent safety risks must be addressed. The safe and efficient operation of AMRs is too important to rely on a single sensor technology. Multi-sensor fusion, or simply "sensor fusion," combines technologies like laser range finding (LIDAR), cameras, ultrasonic sensors, lasers obstacle sensors, and radio frequency identification (RFID) to support a range of AMR functions, including navigation, path planning, collision avoidance, inventory management, and logistics support. Senor fusion also encompasses alerting nearby people to the presence of the AMR.
To address the need for the safe and efficient operation of AMRs, the American National Standards Institute (ANSI) and the Association for Advancing Automation (A3), formerly the Robotic Industries Association (RIA), are developing the ANSI/ A3 R15.08 series of standards. R15.08-1 and R15.08-2 have been released, focusing on basic safety requirements and integrating AMRs into a site. R15.08-3 is currently under development and will expand the safety requirements for AMRs, including more detailed recommendations for using sensor fusion. In anticipation of R15.08-3, this article reviews some of today's best practices related to safety
and sensor fusion in AMRs, beginning with a brief overview of functional safety requirements currently used with AMRs, including generic industrial safety standards like IEC 61508, ISO 13849 and IEC 62061, and the safety requirements for sensing human presence like IEC 61496 and IEC 62998. It then presents a typical AMR design detailing the numerous sensor technologies, presents representative devices, and looks at how they support functions like navigation, path planning, localization, collision avoidance, and inventory management/logistics support.
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IEC 61496 offers guidance for several sensor types. It refers to IEC 62061, which specifies requirements and makes recommendations for the design, integration, and validation of electrosensitive protective equipment (ESPE) for machines, including safety integrity levels (SILs), and ISO 13849 that covers safety of machinery and safety-
related parts of control systems including safety performance levels (PLs) (Table 1). IEC 62998 is newer and can often be a better choice since it includes guidance on implementing sensor fusion, using artificial intelligence (AI) in safety systems, and using sensors mounted on moving platforms outside the coverage of IEC 61496. R15.08 Part 3, when it's released, may make the R15.08 series the best since it will add safety requirements for users of AMR systems and AMR applications. Likely topics may include sensor fusion and more extensive AMR stability testing and validation.
Good, better, best AMR designers have a range of safety standards to consider, starting with general-purpose functional safety standards like IEC 61508, ISO 13849, and IEC 62061. There are also more specific safety standards related to sensing human presence, such as IEC 61496, IEC 62998, and the ANSI/A3 R15.08 series of standards.
Type
Requirement
1
2
3
4
Safety performance in accordance with IEC 62061 and/or ISO 13849-1
SIL 1 and/ or PL c
SIL 2 and/ or PL d
SIL 3 and/ or PL e
N/A
SIL = safety integrity level; PL = performance level
Table 1: Safety requirements for ESPE by type specified in IEC 61496. (Table source: Analog Devices)
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How sensor fusion enables AMRs to maneuver around factory floors efficiently
(is it hazy or smoky, humid, how bright is the ambient light, etc.) and enable a more meaningful result by combining the outputs of different sensor technologies. Sensor elements can be categorized by function as well as technology. Examples of sensor fusion functions in AMRs include (Figure 1): ■ Distance sensors like encoders on wheels and inertial measurement units using gyroscopes and accelerometers help measure the movement and determine the range between reference positions. ■ Image sensors like three- dimensional (3D) cameras and 3D LiDAR are used to identify and track nearby objects. ■ Communications links, compute processors, and logistics sensors like barcode
scanners and radio frequency identification (RFID) devices link the AMR to facility-wide management systems and integrate information from external sensors into the AMR's sensor fusion system for improved performance. ■ Proximity sensors like laser scanners and two-dimensional (2D) LiDAR detect and track objects near the AMR, including people's movement. 2D LiDAR, 3D LiDAR, and ultrasonics 2D and 3D LiDAR and ultrasonics are common sensor technologies that support SLAM and safety in AMRs. The differences between those technologies enable one sensor to compensate for the weaknesses of the others to improve performance and reliability. 2D LiDAR uses a single plane of laser illumination to identify
Sensor fusion functions Mapping the facility is an essential aspect of AMR commissioning. But it's not a one-and-done activity. It's also part of an ongoing process called simultaneous localization and mapping (SLAM), sometimes called synchronized localization and mapping. It is the process of continuously updating the map of an area for any changes while keeping track of the robot's location. Sensor fusion is needed to support SLAM and enable the safe operation of AMRs. Not all sensors work equally well under all operating circumstances, and different sensor technologies produce various data types. AI can be used in sensor fusion systems to combine information about the local operating environment
objects based on X and Y coordinates. 3D LiDAR uses
multiple laser beams to create a highly detailed 3D representation of the surroundings called a point cloud. Both types of LiDAR are relatively immune to ambient light conditions but require that objects to be detected have a minimum threshold of reflectivity of the wavelength emitted by the laser. In general, 3D LiDAR can detect low-reflectivity objects with more reliability than 2D LiDAR.
Figure 1: Examples of common sensor types and related system elements used in AMR sensor fusion designs. (Image source: Qualcomm)
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