Tips for improving safety, ROI for collaborative robots
Collaborative robots are becoming more common on the plant floor. Deciding whether or not to use them, however, requires the plant manager and the workers to consider safety and business considerations and if the robots can benefit the company as a whole.
Collaborative robots have gone through major developments over the last few years as the myth of robots and humans working together in a defined workspace have now become a reality. As the technology continues to evolve, this will become standard on many plant floors for a variety of applications in manufacturing and automation.
Jeff Fryman and Rick VandenBoom examined the attributes of collaborative robots and what they mean for a company's process and automation development in the Dec. 17 Webcast "Changing ROI for Industrial Robotics."
Robotic safety for collaborative robots and return on investment (ROI) for robotics were among topics covered and a collaborative robot technical specification released in February offers more details. More about each presentation follows below.
Safety considerations, collaborative robots
Fryman, a principal consultant for JDF Consulting Enterprises and a retired director with the Robotic Industries Association (RIA), defines a collaborative robot as "A special kind of operation between a person and a robot sharing a common workspace." Furthermore, collaborative operations need to follow specific criteria:
- They can only be used for pre-determined tasks.
- They're only possible when all required protective measures are active.
- They're only for robots with features specifically designed for collaborative operation complying with ISO 10218 Part 1.
The primary feature is safety-rated soft axis/space limiting, which consists of software that provides defined limits to robot motion. The software uses space limiting that is used to define any geometric shapes that define where the robot may do the work. Fryman said that this feature is only available for new robots, and the customer must ask when purchasing the robot for this feature. It is not a standard feature.
Other features mentioned include optional safety-rated speed controls that meet ISO standard 13849-1. Fryman explained that the speed of the tool center point (TCP) does not exceed the limit set for reduced speed and that a protective stop is immediately issued when a fault occurs.
Risk assessment, said Fryman, is a key element of robot safety because each robot system is unique. There are special considerations to make, especially for power- and force-limited robots, and the assessment, as such, needs to be comprehensive. Fryman said there are many important things to consider, such as the plant floor and workspace layout design, limits of the robot system, hazard and task identification, and risk reduction.
Fryman stressed that workspace requirements need to be clearly defined so the operator knows where he can directly interact with the robot. "It may be good to paint the floor, but it's not said in the standard," he said.
The workspace design needs to be flexible so the operator can easily perform all tasks while maintaining a clearance of 500 mm from any trapping or pinch point, which is unique to collaborative robots. When it comes to collaborative operation, one or more of the safety features shall be appropriately selected to ensure a safe work environment for all personnel exposed to potential hazards. Any detected failure of the selected safety features shall result in a protective stop.
"These safeguards are directed toward the integrator and toward how the collaborative application is designed," Fryman said.
This is especially true, Fryman said, when trying to discern the direction of the robot's movement against the human and its possible movement. "It is unsafe if the robot is able to strike the human above the neck," he said. "Anything below that has a number to it, but anything above the neck must be corrected."
The challenge with power and force limitations for collaborative robots is that they aren't well understood. It is a relative issue compared to speed controls, which can be easily measured and defined.
Fryman said he had just returned from a meeting in Japan where the ISO/TS 15066 is being finalized and prepared for publication to provide additional information and guidance on collaborative robots. The ISO/TS 15066:2016 (TS stands for technical specification), "Robots and robotic devices — Collaborative Robots" was published in February 2016 and provides additional information and guidance on collaborative robots.
Understanding automation, process strategies
Rick VandenBoom, automated system group manager for Applied Manufacturing Technologies (AMT), discussed if collaborative robots are useful for a particular company. He said that it's important to determine whether or not it is profitable to change the process to accommodate a robot and what needs to be considered in return on investment (ROI) calculations.
Automation, VandenBoom said, is valuable because it can:
- Improve throughput
- Reduce direct labor costs
- Improve product quality
- Improve worker safety
- Reduce overall footprint.
While there are many good reasons to use automation, VandenBoom warned against getting caught up in automation just because the competition is doing it or because collaborative robots are the hot new trend at the trade show, and you have money to spend.
"You should clearly understand which of these factors are driving your decision process and what their relative importance is," VandenBoom said. "When you automate for the wrong reasons, you end up with failed automation."
VandenBoom also said companies should identify the business requirements of a project, understand the process needed, and determine the appropriate level of automation when deciding on whether to incorporate collaborative robots.
With business requirements, VandenBoom said that it's important to meet the production milestones and part volumes. And that means being realistic. Every company, he said, wants the shortest schedule, highest quality, and lowest cost.
"You can be fast, good, or cheap. Sometimes you can do two, but never all three. Pick two and aim for that as your goal," he said. "Be realistic within your own team and your suppliers."
Determining the appropriate level of automation changes demands a strong understanding of the current process being employed on the plant floor. Knowing where you can improve and where you're already efficient goes a long way. Among the things to consider with a process are the number of processes, the number of operators, types of equipment being used, current cycle time, and current footprint.
"The better you understand the current process the better you can achieve your goals, mitigate risks, and make intelligent trade-offs and achieve synergistic results," VandenBoom said.
Understanding what kind of automation and how much is needed on the plant floor is also crucial. What applies to one company doesn't necessarily apply to another, and each challenge is unique. VandenBoom argues that if a company wants to improve its automation through robotics it should find an expert with a breadth of experience across many industries and applications and mine their knowledge.
"Leverage the experts in these situations," he said. "Don't try to re-invent the wheel."
Regardless of what the company ends up deciding, VandenBoom said that the options that are being considered should be the result of a structured empirical approach that has removed the guesswork out of the potential choices.
"It begins with gathering the right data, following a structured analysis, and presenting multiple fact-based solutions," he said.
Chris Vavra is production editor, Control Engineering, email@example.com.
- Watch the Webcast "Changing ROI for Industrial Robotics" on-demand.
See related articles about collaborative robots linked below.
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