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Do you know the difference between a robot and a cobot?

Robot vs. cobot: the basics

Robots and cobots, or collaborative robots, differ primarily in their interaction with humans and their operational capabilities. While traditional robots operate autonomously in controlled environments, cobots are designed to work alongside humans, facilitating cooperation and shared tasks. Cobots feature advanced safety mechanisms such as force-limiting sensors and lightweight designs to minimize the risk of injury in collaborative settings. Additionally, cobots are typically easier to program and reconfigure, allowing for greater flexibility and adaptability in dynamic work environments. This collaborative nature makes cobots ideal for tasks that require human supervision, precision assembly, or intricate manipulation alongside automated processes.

A list of pro’s and con’s

The characteristics of a cobot – used fully as a cobot – often, but not always include the following:

Smaller footprint
Easier installation and commissioning
Slower
Light tasks
Non hazardous gripper (suction cups, force limited clamping, camera,..)
Limited reach of cobotarm
Lifecycle of 30.000 to 40.000 hours

The characteristics of a convetional robot – used fully as a conventional robot – often, but not always include the following:

Larger footprint, guarding fences and safety lighting curtain around the robot with minimal distance between the fence/safety sensor and robot
Fast
Heavy and complex tasks
No limitations to end-effector or gripper
Larger reaches of robotarm possible
Lifecycle of 80.000 to 100.000 hours

The traps

Occasionally, the payload and reach limitations of cobots are underestimated, leading to inefficient task allocation. Another pitfall is not properly assessing the complexity of the application; while cobots excel in collaborative tasks, they may not be suitable for highly specialized or heavy-duty operations. Where we can speak of strong repeatability (accuracy in moving according to teach points) and even absolute accuracy (accuracy in moving according to distance) with conventional robots of some types and brands, we generally see lower accuracy in cobot variants. Moreover, cobots require strict safety measures according to ISO standard 13849-1 to ensure safe interaction between humans and cobot arms. This means that all peripheral equipment of the cobot must also be included in the risk analysis. Clamping, sharp, or other hazardous grippers must be safeguarded. One should not assume that production speed corresponds to the cycle time of the cobot, even if the cobot is theoretically capable of achieving it.

Depending on the operator’s exposure (face, hands and fingers, chest, etc.), an impact limit applies to what the cobot can cause to a human. Cobots operating at face height of operators (both short and tall) require stricter conditions than those operating at chest height. Both the speed and the texture (soft, hard) of the wrist, gripper, forearm, and elbow of the 6-axis collaborative robot must be thoroughly considered in the risk analysis, as each part has its own texture and speed. A practical impact test is sometimes unavoidable. These impact tests are only reliable when performed on the actual production movements of the cobot. A previously performed simulated impact test can significantly differ from what practice shows, after the actual settings and programming of the cobot have been implemented.

A frequently used safety measure is the safety area scanner, which detects the operator’s proximity and gradually forces the cobot to slow down. In that case, it may occur that the production loss due to prolonged proximity of the operator and consequently prolonged slow cobot speed becomes too great to be profitable.

A risk analysis for a conventional robot (whether a SCARA, 6-axis robot, 4-axis palletizing robot, or delta picker/flex picker) is generally more predictable, as typically, rule-of-thumb methods are used (e.g., safe base distance between robot and fencing or light curtain), and a safety margin can often be taken – to subsequently or during the project, if necessary, increase the height of the fencing or move it further away from the robot. This is, of course, not always the case: In the case of limited space in production, the same iterative method as with the cobot will have to be used to arrive at a reliable risk analysis.

While production is generally not interrupted when working alongside or with a cobot, it might be worth deploying a faster conventional robot, which generates a short production stop during the interaction. Cobots are excellent work partners for many applications; however, research, a clear understanding of application requirements, and collaboration with experienced integrators are essential for making informed decisions when choosing between cobots and conventional robot arms.

VEMECH as your robot or cobot integrator

Vemech guides you through the selection process between robot or cobot, between robot and cobot grippers and give you an insight of the characteristics of different robot and cobot brands.

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