A cobot (collaborative robot) is a robot arm designed to work in the same space as people. It senses force and stops when it hits something, and it can be taught by guiding it by hand. Cobots have spread fast in recent years, especially in small companies and in welding. In this article we explain what a cobot is, how it differs from a classic industrial robot and why “cobots work without fences” is only half the story.
How does a cobot work safely?
Industrial robot safety is defined in ISO 10218, and collaborative operation in the technical specification ISO/TS 15066. There are four ways of collaborative operation:
- Safety-rated monitored stop: The robot stops when a person enters the area and resumes when they leave.
- Hand guiding: The operator moves the robot by hand.
- Speed and separation monitoring: The robot slows down as a person approaches and stops if they get too close.
- Power and force limiting: On contact the robot stays below forces that would harm a person. This is what really makes a cobot a cobot.
Cobot vs industrial robot
| Cobot | Industrial robot | |
|---|---|---|
| Payload | Usually a few kilograms to a few tens of kilograms. | A few kilograms to hundreds of kilograms. |
| Speed | Limited when working alongside people. | High; suited to short cycle times. |
| Safety | Can work without fencing, depending on risk assessment. | Usually needs fencing or light curtains. |
| Programming | Easy, with hand guiding and simple screens. | Needs a teach pendant and expertise. |
| Installation | Light; easy to move. | Fixed mounting and a cell. |
Why “cobots work without fences” is only half the story
The cobot itself may be safe, but the tool on its end and the job it does may not be. A cobot carrying a sharp part or holding a welding torch is a hazard even when it moves slowly. In welding, arc light, spatter and fumes call for curtains and extraction even with a cobot. Every cobot application needs a risk assessment, and the decision on fencing depends on the application, not on the robot.
Cobot welding
Cobot welding is popular in small-batch workshops: the welder holds the torch, guides it to the start and end of the seam, records the points and the robot welds. This is much faster than classic robot programming. Still, each new part needs its points taught one by one, and the cobot’s limited speed and payload may not be enough for heavy work.
DKT’s AI welding robot takes a different approach: instead of guiding the robot by hand, the welder marks the weld spot on the part with chalk. The robot’s camera recognises the mark, finds the nearest seam and welds. See welding robot programming for details.
Cobot or industrial robot?
- Cobot: Light parts, frequently changing jobs, working closely with people, limited space.
- Industrial robot: Heavy parts, high speed, long production runs, enclosed cell.
- Not sure? Look at part weight, cycle time and how close the operator will work to the robot.
Summary
- A cobot is a force-limited robot designed to share space with people.
- It is easy to program and light, but its speed and payload are limited.
- Fenceless operation is decided by risk assessment, not by the robot type.
- In welding, chalk marking removes even the need to teach points one by one.
Cobot or robot? Let’s decide together
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For our services see the industrial robot arm page.