Collaborative Robots and Safety Hand in Hand

In 2008, they were a mere curiosity. In 2012, they were largely viewed as a fad. But just a year later, the industry began to take note. A slew of rivals and suitors entered the fray in 2013.

Now, collaborative robots are here to stay. Many would say they’re the future.

“Collaborative applications is that next new frontier and it’s really going to drive business and applications, and probably applications we don’t even know yet,” says Roberta Nelson Shea, new Global Technical Compliance Officer for Universal Robots headquartered in Odense, Denmark.

An ABI Research study predicts the collaborative robotics market will surge to $1 billion by 2020, populating industry with more than 40,000 collaborative robots.

As a growing number of collaborative robots inhabit the factory floor, safety continues to be a major concern. Collaborative robotics and safety go hand in hand. You can’t have human-robot collaboration without mitigating the risks for injury.

As we mentioned in January’s editorial preview, one of the most anticipated technical specifications in the collaborative robotics realm was released in February. ISO/TS 15066:2016 Robots and Robotic Devices – Collaborative Robots provides data-driven guidelines for designers, integrators, and users of human-robot collaborative systems on how to evaluate and mitigate risks.

Nelson Shea is convenor for the ISO Technical Committee 299 Working Group 3 (ISO/TC 299 WG3) that was responsible for developing the new technical specification. This article summarizes TS 15066, and does a good job of highlighting the finer points, including interviews with Nelson Shea and other committee members. The full technical spec is available on the RIA Bookstore.

Join us for the 2016 National Robot Safety Conference October 17-19 and the International Collaborative Robots workshop October 20!

Nelson Shea has been involved with the robot safety standards since the first committee meeting in 1982, and as convenor for ISO/TC 299, she continues to hold an impartial position in the standards community. She was chair of the ANSI/RIA 15.06 robot safety standards committee for 23 years, and is now chair emeritus. This October, she will also be part of an all-star lineup of speakers for the upcoming National Robot Safety Conference and International Collaborative Robots Workshop in Cincinnati, Ohio.

She says the initial idea of collaborative robotics was met by strong skepticism. “The premise about safety was to keep people away from robots. But then the conversation changed to say if the robot with its tool and part touches you and there’s no injury, why not allow contact?”

Cobots Center Stage at IMTS
Now collaborative robotics is one of the hottest topics in the industry, the focus of numerous articles and workshops, and garnering premier stage time at international trade fairs. At the upcoming IMTS show in Chicago, Illinois, an array of collaborative robots will enter the mainstream manufacturing conversation.

Yaskawa Motoman will for the first time in North America preview its new HC10 collaborative robot at IMTS. The speed- and force-limited design allows it to work safely with, or in close proximity to, humans. Applications include material handling, machine tending, and light assembly applications. Watch the Motoman HC10 cobot in this demonstration video.

ABB Robotics’ YuMi dual-arm robot will also be at IMTS in a hands-on, interactive programming demo for showgoers.

Kawasaki’s new duAro collaborative robot will make its North American debut at IMTS. The dual-arm SCARA robot operates on a single axis and is designed to work alongside humans in material handling, assembly, machine tending, and dispensing applications. Check out duAro in action as its two arms work both independently and as one in this document packing demo (you might want to turn down your volume).

Earlier this year, Universal Robots published an interesting infographic to illustrate the advent of collaborative robotics. You can check it out here.

With collaborative robots, automation is now more inclusive of humans. Even Ford is getting into the act. Watch KUKA’s LBR iiwa collaborative robot on the automotive assembly line.

Robots, Humans Side by Side at GE
Bright ideas are also paving the way for collaborative robotics at General Electric Company.

“Traditionally, the design of automated systems has not factored in people. But with robots becoming mobile and developing a greater capacity to interact with humans, that design paradigm is not the way of the future,” says Roland Menassa, Global Research Automation Center Leader for GE Global Research in Van Buren Township, Michigan.

“Now I can place a robot with fairly decent capability on the factory floor next to people and they can operate side by side,” he says.

Menassa, a General Motors alumnus after 24 years with the automotive giant, is now GE’s resident automation advocate. The Global Research Automation Center focuses on four main areas: robotics, controls, material handling, and work system integration, which tracks the flow of data on the factory floor. GE has embraced the Industrial Internet of Things (IIOT) and automation as a key ingredient. It’s taking the lead on factory optimization, or what it calls Brilliant Manufacturing, to optimize the flow of materials, people and processes within the organization and across its global supply chain.

With its global headquarters preparing to move from Connecticut to Boston, Massachusetts, GE and its subsidiaries has its hands in everything from jet engines, locomotives, and the oil and gas industry, to high-tech medical imaging, drug discovery, and of course, lighting fixtures.

“When I came to GE (in 2013), collaborative robots were starting to move on the market, so I visited different factories within GE to do an assessment,” says Menassa. “We are either a low-volume manufacturer of very large industrial goods such as gas turbines that weigh thousands of pounds, or human-scale, mid- to high-volume products like lighting fixtures and circuit breakers, where you have hundreds of SKUs on the line.

“We’re still going to weld and have robots handling heavy equipment and performing very difficult processes,” continues Menassa, “but when you look at where robotics has gone in the last 55 years, we still see a lot of people on the assembly line. And that’s primarily because of the challenges in compliant material. When we make our circuit breakers or lighting fixtures, there are wires and flexible materials that are very hard to handle. The challenge becomes how do you interject automation in a manual process to handle compliant parts?”

Enter Sawyer, the single-arm collaborative robot by Rethink Robotics. Rethink is probably best known for Sawyer’s big brother, Baxter, the dual-arm robot that became the face of collaborative robotics in 2013, and its renowned inventor, Rethink Robotics Founder and CTO Rodney Brooks. GE was the first manufacturer to put Sawyer to work on the assembly line after the robot’s launch in 2015.

Watch Sawyer on the assembly line at GE Lighting in Hendersonville, North Carolina, where the collaborative robot inserts components into a LED street light fixture before human coworkers complete the assembly.

“The factory never had a robot for many years,” explains Menassa. “So to bring a robot inside the factory, we didn’t know what the workers would think. We had a workshop with the factory, looking at the different applications, looking at where it made sense to apply. We then held several campaigns within the plant itself where we actually had the robot on display. We introduced people to the notion of what that robot can do, how you really can touch it, and how you can work with it.”

Sawyer and Baxter are power and force limited robots, as are the ABB, Kawasaki, KUKA, and Yaskawa robots mentioned earlier, and the FANUC and UR collaborative robots included later in this discussion. Power and force limited robots are specifically designed to have safe contact with humans by way of inherently safe features of the robot or the control system. These types of robots are typically made from lightweight materials, have force and torque sensing in their joints, and may have soft padded skins.

Four Methods of Collaborative Operation, Different Scenarios
Under the ANSI/RIA 15.06 and ISO 10218 harmonized robot safety standards and the new TS 15066, there are four methods, or types, of collaborative operation:

~ Safety-rated monitored stop
~ Hand guiding
~ Speed and separation monitoring
~ Power and force limiting

These tend to be the most misunderstood aspects of human-robot collaboration. To avoid confusion, Nelson Shea suggests that we think of each of the four methods of collaborative operation as scenarios rather than distinct modes.

In every instance you have a shared space among a robot and human operator. In safety-rated monitored stop, the premise is that in a shared space with a person, the robot does not move at all. With hand guiding, a common misconception is that this method is used for teaching. That’s not the case, says Nelson Shea.

“When you’re moving the robot’s arm around to teach it certain tasks, this is not hand guiding in the collaborative sense. It’s not running in automatic when you’re doing that.”

When used to describe collaborative operation, hand guiding indicates a condition where the robot and person occupy a shared space and the robot is only moving when it is under direct control of the person. This video demonstrates hand guiding in collaborative operation.

“In speed and separation monitoring, both the robot and the person can be moving in that space,” explains Nelson Shea, “but if the distance between the robot and the person becomes too close, the robot stops, effectively becoming just like the first scenario (safety-rated monitored stop). In power and force limiting, there can be contact between the person and the robot, but the robot is power and force limited and sufficiently padded or otherwise, such that if there’s any impact, there’s no pain and no injury.”

She says it’s also possible to have any mix of the four methods of collaborative operation represented in one robot system, even all four of them. For instance, in this video of the FANUC CR-35iA collaborative robot, three of the methods are used: safety-rated monitored stop, hand guiding, and power and force limiting.

The new TS 15066 includes formulas for calculating the protective separation distance for speed and separation monitoring. But perhaps the most interesting part of the technical spec is the annex, which contains guidance on how to establish pain threshold limits for various parts of the body, particularly for power and force limiting applications. The data can then be extrapolated to determine speed limits for the collaborative application.

“Although there is information about the four modes of collaborative operation, the more interesting stuff is for power and force limited robots,” says Jean-Philippe Jobin, CTO at Robotiq, a manufacturer of adaptive grippers for collaborative robots in Lévis, Quebec, Canada. “More types of these robots are on the market now, but there was no clear guidance except 10218 to help people safely install those robots in their factories.”

Jobin, along with President Samuel Bouchard and Vincent Duchaine, cofounded Robotiq in 2008 as a University of Laval spin-off. Jobin is also a Canadian technical expert on the ISO committee with Nelson Shea.

Risk Assessment – Application, Not Robot
Both Nelson Shea and Jobin stress that the bottom line for any collaborative robot integration is a risk assessment.

“The risk assessment is the most important aspect,” says Jobin. “If your application requires a little bit higher force or power than what is stated in the document, it does not mean it is not safe. The data we have from this technical specification is relative to pain, while what is required from 10218 is that no injury should occur. There’s a difference between pain and injury. A user could do tests to show that even if they are a bit above what it states in 15066, it’s still safe because they can prove that the robot cannot hurt or injure the people in those specific circumstances.”

He says it’s very important to note that the application is the main concern, not the robot, when assessing risk.

“If you look at the document, it rarely states robot,” says Jobin. “It states collaborative work cell or collaborative application. It involves the cables, jigs, clamps, the robot and the gripper, everything which is inside that cell.”

He says it’s a common misconception that if the robot is “inherently safe” then the operation is safe. Not true. For instance, if your robot is manipulating sharp objects, then it is not safe to have a human beside it, without protective safety measures. Another case is if the robot is handling a heavy object, which could cause injury if it’s dropped or become a projectile at a particular rate of speed.

Safety was a major factor in the robot adoption process at GE Lighting and for instilling worker confidence in the new collaborative robotics paradigm.

“At GE, safety is our overriding priority,” says Menassa. “With any application it’s not about if the robot is safe, it’s about is the task safe? So we do the task assessment risk-based analysis. We observe all the rules and all the RIA standards. We brought people in from RIA to train us. We make sure we understand what the robot is doing, the shape of the end effector, is there anything sharp, and is there anything that could eventually hurt someone? If we feel there is a need for protection beyond just the force or torque limiting capability of the robot, then we’ll place the appropriate safety device, such as a light screen or laser scanner, so we can mitigate the risk.

“RIA publishes the method by which we do a task assessment,” he continues. “We go through the steps of the process and we use their methodology to assess if there’s any risk and how severe it is. We try to do any of the engineering designs around it to mitigate that risk.”

Menassa is referring to the ANSI-registered technical report RIA TR R15.306-2016, Task-based Risk Assessment Methodology. TR 306 describes one method of risk assessment that complies with requirements of the 2012 R15.06 standard and was recently updated in 2016.

Gripper Safety
Although in the works by the ISO committee, currently there are no specific safety guidelines for robot end effectors or end-of-arm tooling in collaborative applications. In the interim, it is recommended that designers and integrators follow the guidelines in TS 15066. Jobin provides an example.

“It’s stated that the operator must not be trapped under any circumstances by the robot. If there’s no power to the robot and you’re trapped, you shall be able to escape by applying minimal force to the robot to remove the part of the body that is trapped. This applies to our gripper as well. If your fingers are stuck between the gripper jaws, in any circumstance, you shall be able to remove your fingers from the jaws to escape any danger (such as a fire).”

Jobin says they have options for Robotiq grippers to mitigate the risk of injuries in collaborative applications. “The options are mostly hardware-based. We have covers to protect people from pinch points on the gripper. In most cases, it is possible to use our product to comply with 15066.”

Robotiq 2-finger and 3-finger adaptive grippers are designed to be compatible with the various collaborative robots on the market. For example, plug-and-play integration kits are available for Universal Robots’ UR-series cobots that include everything you need to install it, the mechanical interface, all the cabling, and the right controllers. The gripper runs on the same controller as the robot and it also shows up on the teach pendant interface.

Check out this story about Whippany Actuation Systems and how easy it was to get started with a new UR robot equipped with a Robotiq gripper in this lights-out application.

One Arm, Two Eyes, Endless Possibilities
Meanwhile, back at GE Lighting, Sawyer was getting the once-over. GE chose Sawyer over big brother Baxter because of its higher payload at 4 kg, better repeatability to +/- 0.1 mm, and its slim profile. Like its dual-arm sibling, Sawyer also has a 7 degree-of-freedom arm.

Sawyer has a kinematically redundant 7-axis arm. This design gives the robot exceptional flexibility, especially in tight spaces or when working with its human collaborators. With 7 axes, you can swivel the robot’s elbow around to avoid contact with other objects or people. Imagine holding your grasp in one location, like on your steering wheel, and still having the ability to swivel your elbow around to place it on the arm rest.

“Now I can operate in very tight spaces, which is very important if I’m working next to people,” says Menassa. “I don’t want to swing the elbow against somebody’s body in order to move the robot in a certain direction (or configuration). That to us is very important when you start to look at smaller footprints of 3 to 4 feet on an assembly line.”

One of the unique characteristics of Rethink’s robots is the animated eyes on its LCD screen. Sawyer’s expressions telegraph its intent.

“People wonder why the eyes on the robot,” says Menassa. “To us, that’s very important. For people to feel safe around these robots, they need to have a sense of what the robot is going to do next. The eyes on that screen are very critical because they look to the left before the robot moves (reaches its arm) to the left.”

But the robot’s animated eyes don’t actually “see” anything. Sawyer has embedded vision sensors in its head and arm for that.

After GE introduced its workers to the robot, the next step was to introduce Sawyer into the production area, explains Menassa. “We took some of the applications that we thought were feasible and mocked them up inside of the plant, but off to the side, where people could start to get comfortable (with Sawyer).

“Having a robot do a task is very simple. The challenge in robotic applications is always the material presentation,” says Menassa. “Where is the material coming from, how’s it coming, how are we going to grab it, and how are we going to hold it? How are the containers going to recycle? What is the best orientation for Sawyer to pick up and drop off, so you’re not going through the gyrations in 3D space? That’s a waste of cycle time. If we fix that, the robot can just execute its task.”

Menassa says it required a bit of trial and error, but they eventually devised a good tactic for part presentation to the robot. “We developed very low-cost holders out of foam and very cheap rack construction, where we can hold up to two hours’ worth of production material in front of it.”

Humans for Value-Added, Robots for Non-Value-Added Tasks
Menassa says there was no need to reconfigure the assembly line. They just dropped Sawyer into the process. In December 2015, Sawyer joined his human coworkers on the main line.

“In any person’s task, whether it’s a 60-second cycle or a 2-minute cycle, you will see 50 to 70 percent is what we call non-value-added,” explains Menassa. “It’s when you walk away from the job to grab a tool or a part, to look at a document, or when you’re walking around the cell. When you finally add the part to the assembly, that’s the only value-added time that you spend. The rest of it is non-value. In fact, some of it is waste.

“Sawyer was grabbing parts and putting them in the assembly. But the human was making sure it was fitting properly and inserting the last screws, using what humans are good at – dexterity, perception and logic. For us, elevating the role of the human on the assembly line to focus on quality – to focus on the value-added – is very important.”

“It was a tremendous win,” he adds. “Here’s a business that needs to expand its volume because of demand. The question is how do you achieve that higher output without adding people? Sometimes it’s very hard to add people because of the space constraints. By adding robots, we were able to achieve higher output with the same number of people, at the lowest cost possible with technology that is low cost and flexible. The notion of low-cost, flexible automation is really collaborative robotics.”

In 2015, GE invested in Rethink Robotics through its venture capital arm. GE Ventures is in good company, with Bezos Expeditions (Amazon founder and CEO Jeff Bezos’ investment company), Charles River Ventures, and Goldman Sachs among Rethink’s other investors.

GE is also developing mobile collaborative robots with partner suppliers, says Menassa. “Coupling collaborative with mobility will give us the ultimate vision of having a mobile robot that can navigate the factory and perform multiple tasks, leveraging every minute of that robot especially in low-volume production.”

Since 2013, GE has collaborated with Clearpath Robotics, a developer of self-driving vehicles. We profiled Clearpath’s industrial division, OTTO Motors, in last month’s article, Mobile Robots and Intralogistics the Always-On Supply Chain. Menassa says GE is experimenting with both collaborative robots and traditional robots mounted on autonomous mobile platforms such as the OTTO 1500 (pictured).

“Now we have mobile robots that can tend CNC and additive machines,” he says. “Bringing robots to machines will allow GE to stay flexible and agile while synchronizing the scale up of our product volumes with mobile collaborative automation.”

GE Ventures also became a strategic investor in Clearpath Robotics for an undisclosed sum last September. OTTO self-driving vehicles have been selected to automate just-in-time parts delivery at a GE Healthcare repair facility in Wisconsin.

Combine collaborative robots with autonomous mobile robots, augmented reality, wearables, and other advanced technology to outfit the smart, digital factory and you have an entertaining prevue into the future of manufacturing. A future where cobots work hand in hand with their human cohorts to be more efficient and productive together.

RIA Members featured in this article:
General Electric Company (user member)
Robotiq
Universal Robots
Yaskawa Motoman