Choosing Between Cobots and Industrial Robots

As the line between collaborative and industrial robots blurs with advancing technologies and new standards, the buying decision can become difficult.

As much as collaborative robots (cobots)—which are designed to share a workspace with humans—have been a game-changing force over the past few years, industrial robots have certainly held their own, as evidenced by the most recent Robotics Industries Association report. The rise of the cobot has, however, created a new set of questions for end users. Whereas end users previously only had to determine the best industrial robot for an application, they now have to decide whether an industrial robot or cobot is best suited for the job.

To help end users in making this determination, Ryan Guthrie, senior vice president of TM Robotics, offers the following list of pros and cons for each robot family.

Cobot Pros:
* Can typically share a workspace with employees;
* If no safety cell is required, initial cost of integration and production floor disruption are reduced;
* Relatively simple to program and integrate; and
* Return on investment can typically be achieved in less than a year

Cobot Cons:
* Risk assessment is required to define need for safety measures, and customers can be surprised by the need for expensive fencing if not prepared in advance;
* Safety precautions can result in very low operating speeds or multiple stops if a human is detected in work cell. Other required safety precautions can significantly increase integration costs;
* Limited reach, payload, speed and accuracy; and
* Collaborative work cells mean operators are still required.

Before reviewing Guthrie’s list of industrial robot pros and cons, it should be noted that, although TM Robotics does not offer cobot products, Guthrie’s list of pros of cons should not be viewed as anti-cobot. In fact, he notes that cobots can be “an ideal first step towards automated processes” that do not require safety guarding. He also adds that cobots can help “employees gain experience and familiarity with robotic systems” as cobots “typically fulfill repetitive or injury-prone tasks such as machine tending or palletizing while the human worker performs higher-value upstream or downstream manual tasks.”

Industrial Robot Pros:
* Much faster and more accurate than a human, even with high payload;
* Fully automated production lines can handle applications that are not conducive to humans at speed, removing operators from unsafe or unclean environments;
* Programming is powerful with extensive integration options;
* Return on investment is usually achieved in 12-18 months; and
* Can be implemented in collaborative applications with appropriate risk assessment.

Industrial Robot Cons:
* High speeds and throughput may not be appropriate for low-volume processes;
* Fixed work cells may require changes to production floor layout;
* More difficult to change processes, which can add costs if outside resources are required;
* May require specialized personnel or outside resources to set up, program and maintain; and
* Industrial robots can be similar in initial cost to cobots, but if a safety cell is required, it adds system integration costs.

Explaining how technology is helping to bridge the gap between cobots and industrial robots, Guthrie said, “Improvements in safety technologies are now allowing industrial robots to be used in collaborative operations, providing many of the same benefits as a cobot along with an increase in payload and speed and reduction in cost for traditional automation.”

With appropriate safety mechanisms in place, Guthrie said “almost any robot is capable of collaborative operation.” He noted that the publication of technical standard ISO/TS 15066 in February 2016 provided industry with safety guidelines for the use of robots in collaborative applications. “The standard explains collaborative techniques and provides force guidelines, maximum allowable robot power and speed and design criteria for robot and robot tool manufacturers,” he said.

During a discussion about the use of cobots at The Automation Conference in 2016, an attendee pointed out that, after purchasing a cobot for use in a production area, OSHA ruled that the cobot required safety caging due to the application in which it was being used. This ruling led the attendee to question the value of cobots in applications such as theirs.

In response to end user experiences such as this one, Guthrie noted that “every automated application where humans are present requires a risk assessment, and collaborative applications require a range of safety mechanisms to keep human workers safe. Cobot customers are often unhappily surprised to find that their application requires a safety cage, which can make the cobot cost similar to an industrial robot without the additional capabilities. If an accurate safety assessment is made up front, buyers can more effectively choose the robotic capabilities that are most important for their application—and often save time and money while better meeting their automation requirements.”

Some of the questions Guthrie recommends answering before proceeding with any robot or automation technology purchase include:

  • What is your automation goal (to reduce employees on production lines, increase output, improve quality, etc.)?
  • Is your environment a safe and desirable place for human workers?
  • Are your processes fixed or highly changeable?
  • Do you want to support manual processes or automate a complete manufacturing line?
  • How much space do you have for automation equipment?
  • What are your scalability requirements to support long-term growth?
  • What are your payload, reach, accuracy and cycle time requirements?
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