Collaborative Robot Do’s and Don’ts
Cobots are the hottest trend in factory automation
Collaborative robots are an important element of Industry 4.0 and smart manufacturing initiatives. Many engineers are intrigued by these next-generation machines that can control force and work safely next to people on assembly lines without traditional safety guarding.
Since cobots first burst onto the scene a decade ago, they have transformed many factory floors and made automation more accessible to smaller manufacturers. The technology has also enabled numerous companies to reshore production to the United States and implement low-volume, high-mix production
“Cobots are especially compelling today for several reasons,” says Esben Ostergaard, the chief technology officer at Universal Robots who pioneered collaborative systems in 2008. “They work together with human workers instead of replacing them—especially valuable where the loss of manufacturing jobs is a sensitive issue.
“We want to place control of factory automation back into the hands of operators,” explains Ostergaard, who recently received the 2018 Engelberger Award from the Robotic Industries Association for his contributions to industrial automation. “Instead of replacing people, we want to give them a tool to do their work more efficiently. We want to remove them from working like robots to becoming robot
programmers and handling more value-added tasks.
“Doing this will perhaps be the best long-term result derived from leveraging collaborative robots,” claims Ostergaard. “This redeployment of human creativity, interspersed with the robot’s repeatability, addresses the market evolvement and customer requirements demanding a high degree of product individualization. It’s qualitative change, both in the products made and for the people making them.”
“Collaborative robots are opening the door to manufacturers that have been apprehensive to automate their assembly lines in the past,” adds Chris Blanchette, executive sales director at FANUC America Corp., which offers five cobot models. “It’s finally bringing a lot of companies on board to the value of automation.”
“A collaborative machine can be set up by operators after only a few hours of training, is light enough to be redeployed around a plant multiple times per day, and can be made to run without fencing and guarding,” says Daniel Moore, technical support engineer at Universal Robots USA Inc. “Functionally, every weakness or difficulty of a traditional robot is obviated by the change in focus.”
“In the past, many people were intimidated by robots,” notes Matt Fitzgerald, vice president of product at Rethink Robotics Inc., which unveiled its Baxter cobot in 2012. “Advanced technology now makes robots more accessible to everyone, especially small manufacturers. Collaborative machines are flexible, easy to use and safe to operate.”
Collaborative robots promise to continue to boost quality, improve efficiency and reduce costs. However, as with any automation tool, their overall effectiveness depends on choosing the right application and planning ahead.
Despite all the hype, cobots have pros and cons that manufacturing engineers must carefully consider. The technology is exciting, but it’s not ideal for some types of applications. For instance, limited payload capacity and slower operating speeds are two drawbacks.
According to the International Federation of Robotics, demand for collaborative robots is growing 60 percent annually. By 2025, cobots are expected to make up 34 percent of all robot sales, up from less than 5 percent of current sales.
ASSEMBLY’s 2018 State of the Profession study confirms this trend. More than one-third (38 percent) of assemblers plan to plan to deploy collaborative robots during the next 12 months. That’s a 7 percentage point increase over 2017 and 12 percentage points higher than in 2016.
Because they are flexible and require little or no safety barriers, next-generation collaborative robots are being used by a wide variety of manufacturers. The machines particularly appeal to smaller companies. For instance, 21 percent of respondents who work for manufacturers with less than 50 employees plan to deploy the technology during the next 12 months. That’s 8 percentage points higher than in 2017.
“Small-to-medium-sized manufacturers are driving demand for collaborative robots,” says Rian Whitton, a research analyst at ABI Research Inc. “This is being driven by demand for manufacturing solutions that don’t include large-scale investment in fixed automation or large robotic arms. These include tasks like machine-tending, quality control and light assembly.”
According to Whitton, smaller manufacturers require flexible automation solutions that can easily and quickly be adapted to meet shifting demands. “They need systems that can be programmed easily and quickly, and can support multiple types of automation tasks,” he points out. “Collaborative robots fit the bill.”
During the next seven years, Whitton predicts that collaborative robot shipments will grow 50 percent vs. 12 percent for traditional industrial robots. And, global revenue for the machines will grow from $292 million today to more than $1 billion by 2025.
This growing demand is being driven by shorter product lifecycles and the increasing use of low-volume, high-mix manufacturing initiatives instead of high-volume, low-mix production.
“Manufacturers need more flexible automation solutions to adapt with speed and efficiency to the market,” says Nicolas De Keijser, assembly and test business line manager at ABB Robotics. “Manufacturing is becoming more specialized and less predictable, which is harder to automate.
“Collaborative automation allows people and robots to work together to make manufacturing more flexible while maintaining safety and productivity,” explains De Keijser. “It increases manufacturing flexibility by allowing people and robots to work on tasks together that previously would have required safety barriers and cages.”
This has challenged previous conceptions about what types of assembly tasks can be automated.
“In the past, assembling large numbers of customized products often meant dull, delicate and repetitive work,” says De Keijser. “With collaborative robots, such as our YuMi [machine], people are able to focus on more rewarding, cognitive tasks while the robot provides tireless precision and endurance.
“YuMi can be set up on any workstation in the factory and redeployed based on production needs without the constraint of traditional safety barriers,” claims De Keijser. “This increases manufacturing flexibility and agility for more frequent changeovers.”
Collaborative robots are popping up in industries and applications that relied on manual assembly lines in the past.
“Many companies are trying to augment some of their lines with automation,” says Blanchette. “They want to address some areas where they may be having ergonomic issues or problems with quality. They can add collaborative robots without changing the configuration of their assembly line.”
General part handling applications are ideal for collaborative robots. Tedious work, such as sorting parts or loading presses, is a good place to start.
“Any assembly task that requires three hands would also be appropriate, with the cobot acting as the human’s assistant,” explains Blanchette. “For instance, the machine could hold a heavier part while the person is joining the assembly together with a screwdriver.
“In applications where lifecycles are short, collaborative robots enable manufacturers to change over to new products very quickly,” Blanchette points out. “We’re also seeing increased demand for cobots in companies with high turnover rates and areas experiencing severe labor shortages.”
The low barrier to entry also appeals to many types of manufacturers.
“We have seen increased demand from contract manufacturers, especially companies that are based in China and Mexico,” says Samir Patel, director of product and applications engineering at Kawasaki Robotics USA Inc. “The flexibility of collaborative robots is popular with electronics manufacturers that want to redeploy the machines elsewhere in their factories.
“For instance, companies that want to change over from one printed circuit board style or size to another simply deanchor our DuAro robot and roll it to the next assembly line,” explains Patel. “They are able to use the same robot on an assembly line, then easily reuse it on an inspection line later in the day, where the robot loads and unloads PCBs in an inspection machine.
“We’ve also seen applications where our collaborative robot is used to assemble gear trains for computer printers and small fan assemblies for cooling electronic devices,” adds Patel. “The robots work side by side with humans, assisting with repetitive tasks that people may have difficulty performing.
“The repeatability of our two-armed collaborative machine is close to a six-axis robot,” claims Patel. “We decided to address that issue when we designed our robot. That makes the machine especially suitable for screwdriving applications, such as assembling tablet computers.
“In one application, one arm of the machine is used as a fixture, while the other one inserts and fastens small 3-millimeter screws that require precise positioning,” says Patel. “Our robot is also used to fasten PCBs inside enclosures. One arm moves the PCB over the chassis, while the second arm inserts each screw and fastens it with an automatic screwdriver.”
Cobots have also been adopted as mobile robotic systems that can move around assembly lines and fill in whenever or wherever needed. That’s the strategy deployed recently at Staubli Corp.’s electrical connectors plant in Allschwil, Switzerland, which features an assembly line equipped with a mix of fully automated and manual workstations.
The HelMo mobile platform is equipped with a Staubli TX2 collaborative robot, which boasts a maximum payload capacity of 15 kilograms and a range of 1,200 millimeters. A touch-sensitive surface stops movements immediately in the event of direct contact with humans. The autonomous robot navigates independently to its assigned workplace, reduces its speed or stops when humans come too close.
HelMo positions itself precisely to within 0.1 millimeter, calibrating its position via three measuring points permanently installed at the workstation. It connects itself to fixed supply sockets for electricity and compressed air by means of a multicoupler and then starts its shift.
“Today, the machine could be placing connector housings and contact pins; tomorrow, it might be positioned at some other stage in the assembly process,” says Olivier Cremoux, business development manager at Staubli Corp. “HelMo is regarded less as a robot and more as an assistant that is flexible enough to help out where needed.
“The intention is…to deploy the robot as a flexible stand-in and thereby increase the availability of hybrid assembly lines or cope with peak demand,” explains Cremoux.
Pros and Cons
One reason collaborative robots appeal to many manufacturers is because they often cost less than traditional robots. They also tend to have a quicker payback and return on investment, since they are more flexible and can easily be integrated into existing assembly lines.
“Typically, our goal is for an ROI of less than nine months,” says Universal Robots’ Moore. “Because of all the hidden costs associated with traditional robotics, combined with the higher possible uptime for a redeployable collaborative robot, we find that the ROI is typically very swift. In our most dramatic examples—often related to injection molding—customers have reported an ROI of three months.
“Automation is fundamentally going to be more consistent and more reliable than human hands for most repeatable processes,” Moore points out. “While most collaborative robot users gauge ROI via labor costs and productivity improvements, many manufacturers also discover quality improvements after installing a cobot. Freeing up labor to assess and improve other areas of the plant then creates other opportunities to automate and reduce waste.”
Collaborative technology can also simplify production lines by permitting more streamlined and functional plant floor layouts. Cobots can be easily inserted into an existing assembly line without doing a lot of reconfiguration.
“Footprints are smaller, because you don’t need all the safety fencing and guarding typically associated with fixed automation,” says Rethink Robotics’ Fitzgerald. “Unlike big, traditional robotic workcells, cobots don’t need to be thoroughly planned out in advance.
“That helps you get going much faster,” claims Fitzgerald. “If you didn’t account for something in the planning stage, you can make up for it with the robot’s flexibility.”
Collaborative robots enable engineers to quickly and easily deploy automation in assembly applications where high levels of human-robot interaction are required. But, safety considerations cannot be overlooked.
In fact, one common misunderstanding about cobots has to do with risk assessments.
“The only real con of collaborative robots is that many people assume they are ‘safe’ right out of the box,” says Corey Ryan, North American manager of medical robotics at KUKA Robotics Corp.
“The reality is that the robot is just part of a system, and the entire system requires a full risk assessment before implementation,” warns Ryan. “For example, a collaborative robot with a drill on the end wouldn’t be inherently safe without additional safety systems to stop the drill before people got too close to it.”
“Many companies buy collaborative robots thinking they can remove typical safeguards,” adds Rick Brookshire, group product manager at Epson Robots. “However, when a risk assessment is properly done, many times the robots still must use traditional safeguarding, such as light curtains, due to the nature of the application. Safe robot does not equal safe application.”
“Don’t think that just because you have a collaborative robot, you can eliminate all safety fencing and other safeguards,” adds Ed Roney, national account manager for authorized system integrators at FANUC America Corp. “One common misunderstanding is that risk assessments are not necessary with collaborative robot applications. However, that’s not the case.
“When you have humans working around automation, you have to consider the hazards that a person could get into,” notes Roney. “For instance, are parts sharp or do they have pointed edges that could pose a safety risk?”
Speed vs. Safety
One of the main arguments against collaborative robots is the fact that the machines trade off speed for safety. To limit force and momentum, cobots simply must operate at lower speeds than other types of robots.
With collaborative robots, there are performance threshold limits that engineers need to be aware of. At a certain point, traditional machines, such as delta, six-axis or SCARA robots, become a better automation option.
“Due to safety requirements, collaborative robots by definition are much slower than typical six-axis machines and far slower than SCARA robots,” says Brookshire. “Many customers don’t realize the speed vs. safety tradeoff until after implementation.
“As with most robot applications, there are always tradeoffs,” explains Brookshire. “To meet safety requirements for true collaborative robots, the top speeds must be reduced. For simple, slow-speed applications this is not an issue.
“However, for higher volume applications, which require faster cycles, speed becomes more critical,” Brookshire points out. “Customers requiring faster cycles generally are OK with safeguarding requirements, as their top priority is throughput.”
“Collaborative robot speeds tend to run slower than high-speed automation,” adds Rick Maxwell, director of the
general industries and automotive segment at FANUC America Corp. “Comparing a collaborative robot to a delta robot is like comparing a biplane to a jet fighter. Speed becomes a critical factor when determining how much force a piece of equipment can contact a person with.
“One of the challenges that manufacturers have had with collaborative robots in the past is speed restrictions,” says Maxwell. “As the technology progresses, we will probably see an increase in speed. But, it will always be a limiting factor whenever people are working within close proximity to robots.
“The best way to decide whether a cobot is right for you is to focus on the application,” notes Maxwell. “If you need to pick and place a part in 0.5 second, a delta or a SCARA robot would be a much better alternative.”
Collaborative robots often look similar to traditional six-axis machines, but are equipped with different features.
“In general, collaborative robots are no different than conventional anthropomorphic robots—merely collaborative variants of them,” says Tobias Daniel, head of global sales and marketing at Comau Robotics and Automation Products. “They don’t need special software to act in a collaborative way, but simple plug-and-play modules that can be loaded to perform specific functions and define new robot operating modes where operators and robots share the same workplace.”
Advanced sensors enable cobots such as Comau’s AURA machine to stop or reverse direction if they come into proximity or contact with a person. The technology combines the use of six safety checks, perceptive and predictive systems that allow robots and humans to work side-by-side.
“Technically, there are four modes of collaboration: hand guiding, power and force limited, speed and separation monitoring, and safety-rated stop,” says KUKA’s Ryan. “The first two modes require specialized robots with force sensing, rounded edges, redundant controls and software. However, speed and separation monitoring and safety-rated stop can be accomplished with traditional six-axis robots just as easily, and probably cheaper, than specialized collaborative robots.”
“Both collaborative and traditional six-axis robots allow high flexibility in motion and can do a wide variety
of applications, which require motion dexterity,” adds Epson’s Brookshire. “Both have speed limitations vs. SCARA robots, although traditional six-axis robots are generally much faster than collaborative robots.
“For simple applications, collaborative robots can be a better fit, due to the simplicity in creating the applications, thus allowing end users to develop solutions,” notes Brookshire. “However, as applications become more complex, the advanced tools, language features and integrated options available with traditional six-axis robots generally make them a better choice.
“SCARA robots are all about speed and precision and are generally far superior to collaborative robots in both areas,” claims Brookshire. “If an assembly application requires speed, precision or some level of complexity, a SCARA robot will, in most cases, be the better choice.”