Author Topic: Quicker energy control for cell entries  (Read 294 times)

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Offline NPG92

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Quicker energy control for cell entries
« on: August 12, 2018, 03:33:45 AM »
In my place of work, employees quite frequently have to enter robot cells and do things to our machines as part of the process. I'm looking for alternative/quicker but still safe ideas to locking out the cage every time they need to go in and out. Any ideas?

Offline Fabian Munoz

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Re: Quicker energy control for cell entries
« Reply #1 on: August 12, 2018, 05:45:20 PM »
NPG92

wow. The more I read your post the more i get confused

The moment you say "cell" i'm thinking guarding. Then I'm thinking door with safety interlock. The safety interlock have to be able to disable all source of energy (there are special cases)
This includes stopping the robots. etc, etc (We don't have a clue of your layout)

I don't think there are alternatives for safety.  It's safe to get in or not
« Last Edit: August 13, 2018, 02:28:57 PM by Fabian Munoz »
somar

Offline TygerDawg

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Re: Quicker energy control for cell entries
« Reply #2 on: August 13, 2018, 12:44:24 PM »
You are entering the emerging realm of collaborative robotics.

A good example I have seen is a video from the Kuka website.  Obviously staged for marketing purposes but illustrates the theory well.  Perhaps it is still there and you can find it.

It showed a collaborative robot assembly work cell with the robot working in some sort of "zones."  Inside the fast zone, robot moves at process speed.  Inside the collaborative zone, the robot is slower and is constantly checking sensors and servo feedback for presence and collisions with humans.  In the video I saw, a doofus is talking to a cute girl and lays his hand on the work piece while the robot attempts an assembly process.  Robot bumps into doofus' hand and retracts and attempts assembly step again.

Other than that, read and implement the Robot Safety Standard RIA/ANSI 15.06 to keep from getting sued by the  worker who was injured in an unsafe robot work cell.  A lot of interesting things can be done with modern laser safety scanners these days and this may be something to investigate.
TygerDawg
Blue Technik
Virtuoso Robotics Engineering
www.bluetechnik.com

Offline NPG92

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Re: Quicker energy control for cell entries
« Reply #3 on: August 16, 2018, 05:37:03 AM »
I don't... I ca.... Ok. Robot cells, yes I'm referring to guarding. Electronic single-contact interlocks themselves are not safe, as anyone can walk by and shut the door while someone is in the cell. To make this type of setup safe, employees are required to physically "lock out" the door so it cannot be shut. However, they have to be in and out of the cell so often that physically locking and unlocking a master lock every time would be very time consuming. The question is, are their safe alternatives to physically locking out a robot cell's entry, for when an employee needs to enter

Offline SkyeFire

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Re: Quicker energy control for cell entries
« Reply #4 on: August 16, 2018, 12:51:26 PM »
Yes.  Safety mats on the floor inside the cell, that register when someone is standing on them, wired into the safety circuit.  Or area scanners, like this Keyence unit: https://www.keyence.com/products/safety/laser-scanner/sz/index.jsp, that achieve the same result by laser-scanning a programmable area at ankle height, and breaking the safety circuit if anything is in the danger zone.

Offline TygerDawg

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Re: Quicker energy control for cell entries
« Reply #5 on: August 16, 2018, 12:54:56 PM »
If you followed the RIA/ANSI safety standard, you would perform a hazard analysis.  In every case I can imagine in which a work cell operation can allow a worker to enter the hazard zone and have the safety door closed and enabled behind them, then your hazard mitigation would require redundant safety features.

Translated concisely:  a safety-switched door by itself is not sufficient.  The cell must also have floor mats, light curtains, laser safety zone scanners, hand-held safety deadmans, or a combination of all.  You must guarantee that a worker cannot be in the work cell while the robot is in automatic mode.

The safety equipment market is full of useful devices with brochures and manuals to explain their application.  These bits are complimented by effective work cell design and production system design that will allow entry by workers as needed to support production.  But only in a safe manner.  This takes of the form of good safety circuit design and good controls programming.
TygerDawg
Blue Technik
Virtuoso Robotics Engineering
www.bluetechnik.com

Offline RoboWeld

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Re: Quicker energy control for cell entries
« Reply #6 on: August 17, 2018, 09:50:29 AM »
I don't... I ca.... Ok. Robot cells, yes I'm referring to guarding. Electronic single-contact interlocks themselves are not safe, as anyone can walk by and shut the door while someone is in the cell. To make this type of setup safe, employees are required to physically "lock out" the door so it cannot be shut. However, they have to be in and out of the cell so often that physically locking and unlocking a master lock every time would be very time consuming. The question is, are their safe alternatives to physically locking out a robot cell's entry, for when an employee needs to enter

We use a "key exchange" system, every trained person has an access key which when inserted will open the safety circuits, release the gate bolt and a 2nd "pocket key" which you keep on your person (in your pocket  :icon_smile:) while working in the cell.

Example: https://www.fortressinterlocks.com/Product/107/xmr-xmrs-modular-key-exchange-unit-with-switches