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How to Shop for a Collaborative Robot

There are a lot of "how to" guides out there, like "how to shop for a computer" or "how to shop for a smartphone." However, there are very few guides on "how to shop for a robot" and definitively less "how to shop for a COBOT." The engineers at Robotiq have filled that void with some basics to consider when shopping for a robot for your plant.

Collaborative robots or Cobots are a type of industrial robot that is safe for human-robot collaboration. In fact, with different embedded safety sensors and compliant shapes, the robot is designed to work alongside humans without harming them even if they happen to touch each other.

These robots are used mainly in small workshops where flexibility and space is a concern. Since this robot can be adapted to a lot of different applications with very easy programming methods (hand guiding) and by the fact that the robot does not need rigid fencing as regular industrial robots do.

Cobots really suit SME needs. Applications such as machine tending, packaging, product testing and finishing are just a few that are done by these robots.

Start Small and Build from Experience

That being said, integrating a collaborative robot is also different from a classic industrial robot. In fact, it is so simple to install, program and use that you can do it yourself even if you have very little robotic or automation background. Our first tip would be to start small and build from this first integration, so you can lead up to more complex applications. In fact, with all the different sensors and devices out there you can easily get lost in a very futuristic robotic cell.

What we recommend is to find an application that does not need a lot of modifications to its actual setup and simply insert a cobot with only the minimum necessary components. From there you can see what works and what doesn't. After this you can either adapt your cell or you can learn from any mistakes and enhance your next application with what you learned from your first integration.

However, if your application really needs complex devices and a high level of complexity, we do recommend you use an external service provider to help you speed up the integration.

Be Aware of These Top 5 Specs

As you start your robotic application assessment you need to look at 5 major points when pre-selecting your robot. Here is a list of specs you need to be aware of before heading out to do your robot shopping.

Payload: In other words, the maximum load that the robot will need to carry. Calculate your part weight and don't forget that the robot tools have to be included in the payload. Using a robot with a payload at max will trip your robot into "error" mode often, because it will be constantly detecting too large a force. On the other hand, you don't need too strong a robot either. The size of the robot will be impacted by the size of the payload, the larger the payload, the larger the robot.

Reach: This is the distance the robot will need to travel during the whole application. When looking for this data, measure stuff like the depth of your machine or the maximum reach that the operator needs to reach right now. Notice that data such as degree of freedom has to be considered in some applications since it can have a direct impact on the flexibility of your robot. Most of the people use 6-axis robots, however, your application may only require a linear robot (3-axis).

Repeatability: This concept is often mixed up with accuracy and precision in the robotic world. In a collaborative application, you want a robot that will repeat its motions within a certain area. Since you will not be doing offline programming, you don't need accuracy. In fact, what you need is for the robot to return to the place it was instructed to go to during its programming. You can generally compensate for a lack of repeatability either through mechanical stops or force sensing. Both methods will provide for a good positioning of the part.

Ease of programming: This should be a spec though it isn't actually a spec. In fact, you cannot put a number on this, but this is definitely something you want to know before buying a collaborative robot. One of the main advantages of using a cobot is to be able to program it easily, with minimum training. Some collaborative robot manufacturers will prefer to continue the old fashion way and keep offline programming, for this you would need to hire a full time programmer to make things work. So make sure your robot can be hand-guided and easily adjusted.

Safety: A lot of people think that collaborative robots have or should have rated safety features with force and speed thresholds. Perhaps this is true, but it seems that most robot manufacturers do not provide this kind of information in their specification sheets or even in their instruction manuals. It is sometimes not quite clear what the real forces are that can be applied by the robot.

You should then look at the spec sheet to figure out the different safety settings of the robots or ask your local representative for a demo on the safety features of the robot. Notice that while collaborative robots claim to be safe, a complete risk assessment must still be done when integrating these robots. In fact, even if the robot is safe, this doesn't mean the application itself is safe for human robot collaboration.

Also notice that specs such as robot weight, speed, accelerations and so forth can be found on the spec sheet. If one specification is more important to you, make sure the robot matches your expectations.

End-Effector/Tool Specification

As the robot can't be used without any tooling, we do recommend that you spend some time looking for the right tool to make sure your robot can really do the job. There are 2 types of end effector that are generally used.

Grippers

There are a lot of different grippers on the market. However, just a couple of guidelines can help you figure out your needs:

Process Tools and Sensors

If you are doing deburring, screwing or other process jobs that require a certain tool make sure to ask your local tool provider for further information on the way to automate these tools.

Sensors can also be added to the robotic cell to give a supplementary sense to the robot. In fact, devices such as Force Torque Sensors are used in many industries to give the sense of touch to the robot.

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