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Putting Safety First in Robotic Automation

Pat Waurzyniak
By Patrick Waurzyniak Contributing Editor, SME Media

New ISO safety specification helps automation developers design safer robots for close encounters on the factory floor

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Fast-moving ABB robots employ a variety of safety features to keep workers safe from accidents. ABB recently expanded its SafeMove software technology to help ensure factory-floor safety.

Since the start of robotics, safety has ranked as the top priority for robotic automation developers. Besides being the first item in Isaac Asimov’s Three Laws of Robotics, taking the “do no harm” approach is pretty much mandatory with the speed and strength of today’s industrial robots that are most widely used for heavy lifting on automotive assembly lines and other industrial manufacturing venues. But with the advent of newer collaborative-type robots that have lately come on the scene, the rules of robotics are being rewritten with new specifications updating how to include these smaller, lower-payload, slower-speed robots that can work side-by-side with workers on assembly lines.

The ISO/TS 15066 technical specification was refreshed with the publication in February 2016 of the ISO/TS 15066 technical spec that gives robotic automation developers and users specific new guidelines for design and proper implementation practices for deploying new collaborative robots on the shop floor.

This revised ISO/TS 15066 specification expands on sections specifically dealing with collaborative robots, or cobots as they’re sometimes called, and it also builds on the ISO 10-218 standard. The 15066 specification and ISO’s standard describe guidelines covering collaborative model use within four main areas, including safety-monitored stops, hand-guiding, speed and separation monitoring, and power and force limiting.

Making Inroads into Automotive

Up until very recently, automation developers aimed collaborative robots mostly at very lightweight assembly applications. But this cobot class of smaller units recently has made some headway into the automotive realm—which historically used larger, higher-payload robots for heavy lifting—for some new auto assembly applications. For example, Ford Motor Co. (Dearborn, MI) announced on July 14 that it started testing new cobots from KUKA Robotics at its assembly plant in Cologne, Germany, where Ford Europe builds the Ford Fiesta car model (see story and Ford video link at http://tinyurl.com/gnnalou.)

In a conjunction with robot manufacturer KUKA Roboter GmbH (Augsburg, Germany), Ford initially tested the small, 3′ (0.9-m) high KUKA collaborative robots on an assembly line helping workers install shock absorbers. Rather than use a heavy shock absorber installation tool, the workers have the robot lift and automatically position the shock into the wheel arch before pushing a button to install the component.

“Working overhead with heavy air-powered tools is a tough job that requires strength, stamina, and accuracy. The robot is a real help,” said Ngali Bongongo, a production worker at Ford’s Cologne plant. Equipped with sensors, the collaborative robots stop immediately if they detect an arm or even a finger in their path, ensuring worker safety. Similar technology also is used in the pharmaceutical and electronics industries. Developed over two years, this specific automotive robot program was carried out in close partnership with KUKA in Germany.

Ford’s Cologne assembly plant trial is part of the company’s investigations into Industry 4.0, a term describing the Fourth Industrial Revolution, which embraces automation, data exchange and manufacturing technologies. Ford sought feedback from more than 1000 production line workers to identify tasks for which the robots would best be suited, according to the company. “Robots are helping make tasks easier, safer and quicker, complementing our employees with abilities that open up unlimited worlds of production and design for new Ford models,” Karl Anton, director, vehicle operations, Ford of Europe, said in a statement.

The possibilities for collaborative-style robots are tremendous, noted Rick Maxwell, director of engineering, FANUC America Corp. (Rochester Hills, MI). About a year ago, FANUC introduced its 35-kg payload CR-35iA collaborative robot, which Maxwell said is the largest power-enforced robot on the market today with over 1800 mm of reach. FANUC also plans this fall after IMTS to introduce a new smaller model, the CR-7iAL, a 7-kg payload cobot with 900 mm of reach, that will be aimed at smaller material-handling applications.

For many automotive applications in particular, collaborative robots that can lift a substantial amount of weight, like the CR-35iA’s 35 kg (78-lb) payload, show a lot of promise for alleviating a number of repetitive strain injuries among workers. Maxwell noted that the next largest cobot payload in the industry is in roughly the 10 to 14–kg range.

“You start to get into the ergonomic [issues] where you really can’t pick up repeatably 20–30 lbs [9.1–13.6 kg] without having a lift assist,” Maxwell said. “We do have robots in production. They are working on assembly lines or in areas where there are people.” FANUC has tested its CR-35iA robot on assembly lines, Maxwell said, and the company has worked with General Motors Co. (GM; Detroit), which presented its experience at a workshop put on by the Robotic Industries Association (RIA; Ann Arbor, MI). “They’re deploying collaborative robots, they’re deploying them in areas that have heavy human traffic, but they’re taking a conservative approach. I see a tremendous amount of potential.”

Keeping It Safe

Most of the time, industrial robots function very safely, given the advanced array of safeguards available to install in factory automation workcells. Many safety features and technologies have existed for quite some time, with robotic developers and integrators using safe zones, fencing, and other technologies to ensure safe robot operation. When accidents do happen, it is a fairly rare occurrence and the cause is often due either to operator error or to mistakes made during setup such as when a worker has entered a robot’s operating zone, as was determined to be the case in a fatality that occurred last year at a Volkswagen plant in Baunatal, Germany.

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Ford Motor Co. recently announced it was testing collaborative robots from KUKA Roboter GmbH on the assembly line in Cologne, Germany, where Ford Europe builds its Fiesta models. The KUKA cobots assist line workers with an overhead shock absorber assembly operation.

In the most recent ISO/TS 15066 specification, several factors related to collaborative robots were studied. “That’s one small piece. That’s the bio study of pain thresholds and points of impact on the human body,” said George Schuster, business development manager, Rockwell Automation Inc. (Milwaukee) and a TÜV-certified functional safety expert, speaking about the ISO/TS 15066. “That’s really intended for one of the four collaborative applications that we call power and force limiting, where people and the robot are designed to interact or are anticipated to come into contact.

“This is one of the least well-sorted out of the four different collaborative applications, but it’s one of the most attractive because in general, these collaborative applications really represent a real change in the way that people and machinery interact,” Schuster added. “It’s a very, very exciting space to be working in, because it really allows us to leverage—in ways that we never could before—the strength, the tirelessness, and repeatability and the accuracy of the machine, with the intelligence, adaptability and understanding of the human, and really have those two sides complement each other. And it’s really enabled by safety technology generally and so, but it’s a real new way, it really changes the way people and machinery interact.”

That 15066 spec is among the four collaborative robot modes, he added. “The specification that is most relevant is the ISO 10218-1 and ISO 10218-2, so this is a fully harmonized safety standard with the ANSI/RIA 15.06-2012.” Schuster, who spent 15 years at GM before joining Rockwell in 1997, was one of the early proponents of collaborative-type robots and has worked with them since about 2005. He recently did some prototype work with cobots that has now been deployed into a pilot application at Fiat Chrysler Automobiles (FCA; Auburn Hills, MI).

“A lot of times, people get a little bit confused about this collaborative robot topic, and they think of it as a robot technology, you buy a collaborative robot and put it in, now you have a collaborative robot,” Schuster said. “I will tell you it’s not. … It’s an application. It’s the way that robots are processed to be utilized and in the way that they are designed to interact with people, and so it’s not really specific to a robot technology. It’s more of an application. Long before people were selling ‘collaborative’ robots in the market, we were doing collaborative robot applications, and carefully [programming] the position and interaction of the machine.”

Defining Collaborative

Among the four different collaborative modes of operation defined in ISO 10218, the first one, a safety-rated monitored stop, has been around for some time. “This is the most common mode of collaborative, and we’ve used this for many, many years,” he said. “We’ve had safety-rated monitored stops on a robot for as long as I’ve been in this business.”

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The FANUC CR-35iA collaborative robot has been used in automotive applications, such as this tire-loading operation. The 35-kg payload cobot has the largest current payload of any collaborative model on the market.

A safety-rated monitored stop is a way to coordinate the robot’s motion with the motion of a person and it is intended in that type of application that the robot and the person would never ever come into contact. “It is a way to, for instance, arbitrate a shared space between the robot and a person and to coordinate that space via the cell-level safety control system,” Schuster said.

Safety technology typically prevents most fatalities like the one that happened at the VW plant. “In a proper design, that shared space would be arbitrated by technology, so we would have sensing devices that would sense the position of the person, either with light screens or laser scanners or floor mats, and then we would have instrumentation on the robot to detect its position in relation to that shared space, so that we never let them in the same space at the same time,” Schuster said. “So there’s always sensing—sensing the human and sensing the robot—and the cell-level safety control system then coordinates those two.”

A second collaborative mode, hand-guided operation, is quite a bit less common, Schuster said. “This is where the robot kind of goes into what we call a zero-gravity or a float state, and one can actually grab the robot arm and move it to a position and then have it grip the part and then use the robot’s strength to move the part in position,” he said. “You have to think of it as kind of either like a load assist or that some people are using it as kind of a hand-guided teaching operation.”

The third mode of collaborative operation as defined by ISO 10218 is speed and separation monitoring. “This is kind of like the first one, but a little bit more sophisticated. My colleague calls it ‘dancing with the robot.’ This is where we are able to modulate the robot’s speed, and possibly its position, based on its proximity to the person. For instance, let’s say that a robot is operating, and as you approach the robot you are detected, the robot will slow down and modulate its speed. We do this today all the time, so this is not new. This has been done for quite some time. At some point, when you get too close we will put the robot into the safety-rated monitored stop.”

The fourth mode, power and force limiting, is really the least sorted out of the four collaborative modes, Schuster said. “It’s really an emerging capability in the robot that allows the robot to modulate its force, or power, if the robot were to accidentally come into contact with the worker. This is where ISO TS 15066 comes into play—this defines dozens of different places on the human body, and the limits of pain on the body.” That aspect defines how much force can be applied to someone’s cheek, or on the leg or thigh, for instance. “It also defines it in the shape of the mechanical thing that’s touching you,” Schuster said. “If it’s a sharp pointy piece, this is where the tricky part comes in.”

What’s needed are proper risk assessments and system integration, he stressed. Rockwell also recently announced an expansion of its global Machinery Safety System Integrator program that was started in 2014.

New Safety Software

For its lineup of YuMi collaborative robots, ABB Robotics recently debuted an expanded SafeMove2 software, the latest generation robot monitoring software. “Closer collaboration between robots and people brings many benefits such as increased flexibility and productivity, this is exactly why we developed this technology and the SafeMove2 product,” said Hui Zhang, head of Product Management, ABB Robotics (Auburn Hills, MI). “It is also important to note that Safe-Move2 can work with collaborative robots as well as conventional, standard industrial robots.”

ABB’s new software updates its original SafeMove introduced in 2008. “Simply put, SafeMove2 is a software solution that allows robots and operators to work closer together by restricting robot motion to precisely what is needed for a specific application,” Zhang said.

The SafeMove2 technology establishes safe zones, which help optimize the size of the cell on the factory floor while protecting people and equipment, and it sets safe axis ranges for a given application, rather than relying on electro-mechanical switches, Zhang said. This increases control and flexibility while reducing maintenance requirements on mechanical parts.

“It also defines and sets safe robot speeds, so operators can work within the proximity of the robot. This is a big productivity advantage over safety systems that completely stop a robot when people come close,” he added. “It ensures safe standstill supervision of the robot axis, so an operator can work in close proximity to a robot without having to switch the robot motors off.” SafeMove2 also includes a cyclic brake check so brakes are checked on a regular basis to ensure their reliability.

Zhang said SafeMove2 is part of the increasing trend for digitalization in automation, and represents an evolution from hardware to software. “This new generation of SafeMove integrates safety features directly into the robot controller software for full flexibility and expandability,” he said.

Fast, Easy Cobot Deployment

Collaborative robot pioneer Universal Robots (Odense, Denmark) plans to introduce its new showroom of plug-and-play application solutions, called Universal Robots+, at IMTS in Chicago. The online showroom is being touted as offering companies a new level of simplicity in gaining the applications needed to hit the ground running when installing their next UR collaborative robots from Universal, which was founded in 2005.

Universal Robots+ lets distributors and end users choose accessories, end effectors and software solutions from Universal Robots, speeding up deployment times on installing the UR3, UR5 and UR10 model cobots for manufacturing applications. In addition, the company will introduce a free developer program, called +You, for marketing and support given to UR robot application developers.

“We’re getting to the point where the early adoption stage is ending, and they’re [collaborative robots] getting more accepted in the production environment,” said Douglas Peterson, Universal Robots general manager, Americas. “Companies are testing them and the biggest trend is the closer they’re getting to working with humans. Robots are getting out of their cages and working alongside people, and making automation more accessible.”

Key features of UR robots are that you don’t have to be an engineer with 10 years’ experience, Peterson noted, and they can be easily redeployed. Collaborative robots are light enough to put on a cart where workers easily wheel them around to redeploy them as they’re needed. “We’re seeing them in a lot of machine-tending applications.”

With a collaborative robot, the time it takes you to unpack it to the time it’s in use is very minimal. “We call it an out-of-the-box solution. Payback for our robot is about 195 days, in some cases one year, or as low as one to two months,” Peterson said, adding that it takes only about an hour to unpack and put into service.

Programming a UR robot is easy, too, allowing a novice to program simple moves in no time, he added. “You have a device that’s similar to an iPad. It’s a touchscreen using arrows,” Peterson said, “and you can program in different way points. You can also use the arm to program it.”

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