What is the difference between a traditional industrial robot (typically a six-axis robot) and collaborative robot?  What types of applications make sense for each? In part one of our two-part series, we will explore the background, pros, cons and applications of today’s collaborative robots.

Background

Industrial robots have been around since GM implemented the first one for a die-casting process in 1961.  They are a generic handling machine that can be made to fit a variety of purposes, as opposed to more purpose-built automation that only performs one function well.  The most common industrial robot today is a six-axis—or six-jointed—arm with a tool affixed to the end.

Difference Between Six-Axis and Collaborative Robots

We typically see industrial robots in their own work cells.  A swinging robot arm can be a dangerous piece of equipment, so access to the robot is controlled with fencing or light curtains.  Product is typically brought into and out of the work area using another type of automation.

On the other hand, collaborative robots—sometimes called “cobots”—don’t need a segregated work cell.  They monitor current draw on their motors or have embedded sensors that can tell if the robot has come in contact with another object it wasn’t expecting (like a person), and the robot stops.  This additional safety measure allows robots and people to work alongside each other. 

The robot can make a single worker much more efficient or can replace a worker’s repetitive task in a small area where a traditional robot’s extra infrastructure won’t fit.  Additionally, the cobots tend to have a less expensive implementation cost than traditional industrial robots due to the need for expensive safety equipment being removed.

Pros and Cons of Collaborative Robots

To make it easy to understand which type of robot may be better for an application, let’s outline a few pros and cons of a cobot. Pros:

• Expense: cobots are typically less expensive than a six-axis robot.  Oftentimes, companies can see an ROI that is strong enough to have a payback within a year.
• Easily re-purposed: many cobots come with software that allows someone to reprogram the machine by physically moving it around to its task points (vice recoding the software driving it).  This means a cobot can be moved to a new job and performing a new task within an hour or so.
• Flexibility: the ability to work safely outside of a dedicated work cell means that people can augment the robot’s work (and vice versa), allowing operations to realize higher productivity without either additional labor or extensive capital investment.

Cons:

• Speed: in order to be safe, cobots aren’t as powerful as most six-axis robots.  High-speed applications generally can’t be solved with a collaborative robot.
• Payload: just like speed, the lower power limits the applications of the cobot.  With some exceptions (such as the FANUC CR-35iA, which can lift up to 77 lbs.), cobots are best fit in applications with lower payloads.

Collaborative Robot Applications

Knowing the strengths and weaknesses of cobots, where do they make the most sense?  Typically, they’ll find homes in applications where they move light products relatively slowly, such as these:

• Machine tending: whether a machine is deburring a part, applying a coating, or conducting a heat treatment, there is a cycle time of the machine itself that causes it to be the bottleneck in a process.  If a person doing that job would have to wait any more than a couple seconds for a process to happen, the slightly slower cycle time of a cobot becomes a non-issue.  Paying a worker to swap parts in and out of a machine isn’t the best use of their time or an operation’s labor budget.  A cobot could move parts in and out without affecting the over cycle time of the process while reducing cost and increasing accuracy (they always line up small parts pretty close to perfectly).
• Parts assembly: for small parts assembly that doesn’t require blazing speed (think small electronics, not ten million daily bottles of soda), a cobot can be an added efficiency in an operation.  In particular, cobots can assist workers in a complex assembly process.  A typical application may involve the robot doing basic movements while its human counterpart completes a complex inspection or difficult manipulation.  The robot saves the worker time by doing the easy portion of the job, allowing the worker to apply their skills a higher percentage of the time instead of just moving pieces around.
• Packing: when the same part (or series of parts) is going out for shipment, a cobot can free workers up to perform more meaningful tasks.  Additionally, cobots always follow packing guidelines—never overstuffing boxes or underpacking dunnage.
• Vision systems: cobots can be integrated with vision systems.  Whether they’ll be doing a basic inspection of a part or using the vision system to pick parts out of a jumbled container, vision systems can enhance any robots functionality.  While seeing the applicability of a robot where parts are presented in uniform, easily-repeatable positions, pulling parts from a bulk container may seem like a job only a human or complex (and expensive) singulating machine could do.  However, integrating a vision system allows the robot and its associated software to decide which part is the most accessible (just like a person would do), then adjust its manipulation to grab it.

Conclusion

Collaborative robots are opening up new possibilities for opportunities to automate an operation.  While they won’t replace traditional industrial robots, they are an excellent way to enhance the spaces where robots can help make our lives easier and our processes more efficient.  Hopefully, seeing a few applications where cobots have been successful can spark new ideas for their implementation.

For more information, contact our team or read part two of our series: Collaborative Robots Part 2: Benefits and Expanding Capabilities

Author: Ahmed Arif