Safety

[Nation]

I have a cell that has a cable tray that carries 480V supply lines, and high pressure hydraulic lines running above the robot. When I say above, it will be about a foot above the robot.

Is there any sort of safety standard that says not to do this? I really do not want to have this above the robot. One fat finger and there will be a fried robot and hydraulic fluid everywhere. The customer is adamant that it stays where it is.

I've read through the RIA 15.06, and the closest thing I can find says "the robot system shall be installed to provide a minimum clearance from the operating space of 0.45 m (18 inches) from areas of building, structures, utilities, other machines and equipment not specifically supporting the robot function that may create trapping or a pinch point." However, since the cable tray runs above the robot, I do not think this applies.

[Jim Tyrer]

Does 'a foot above the robot' mean a foot above the robot's maximum envelope?

[TygerDawg]

Jim makes a good point, and I'll expand this by inviting you to follow me to "Worst Case Scenario Land". 

Are you concerned about your liability?  You darn well should be.  Is the customer concerned about the safety of his own employees?  Employee safety should be his first 12 priorities.  If you need 3rd party advice on the interpretation of the ANSI/RIA 15.06 standard, then pay for a consultation from those guys at the RIA.

But back again to the two questions:  one must take the PFMEA approach to this, or the Risk Analysis approach to this.  Despite great leaps of improvement in robot / controller reliability over the past couple of decades, only a fool will believe that nothing can go wrong.  I got my Wake Up Call earlier this year when my late model Hunk O Junk KUKA KR30HA almost killed me.  Visualize what would happen if the wires from one of the encoders started to fatigue-fail and the encoder gave erratic signals back to the controller.  And the servo was commanded to do really bizarre motions.  Which caused the robot to wipe out the 480Vac & hydraulic lines.  Which electrified the entire workcell and pierced the eyes of any operators with high pressure hydraulic fluid streams.  And the entire workcell erupted into a high-temperature conflagration spewing vast amounts of toxic fumes?  What then?

This is the litigious world in which we live.  If you wound up in court over this, would you have wished (1) you had walked away from this job or (2) you had paid to get an Expert Engineering Opinion about the installation?  Or both?

[Fabian Munoz]

I understand what you guys are saying, I agree, I'm with you, etc, etc BUT

robots are used to do dangerous task for humans, therefore they will carry dangerous or potential dangerous items when the move/
Let me give you an example, I installed, programmed, etc many, many waterjet cells and everybody was worry about the robot crashing or the operator bypassing safety and been hit by the robot but nobody (ok, maybe one customer) asked me what happens if the piping carrying 65000 psi explodes while the robot is in motion.

Another example,  scooping melted aluminiun, the scoop breaks and then, well, just picture.

My points is (unless I'm totally off topic) that is what robots do, they go and work where is dangerous. The solution for me is not preventing the robot to go crazy and cut all the power and hydraulics lines, it is preventing if that happens the cell is big enough so no human can stand closer to the dangerous area. We live in a world where real state is too expensive, customers want to put robots right beside human, but every situation is different, I guess this is the reason that nobody wants to write  the law.

If you are really concern (and we are), ask the customer to sign a document that acknowledges the problem, I guess that the best you can do, the problem now is not on your hands BUT THE REAL PROBLEM WHICH IS THE LOST OF A HUMAN LIFE still there.

[Nation]

Does 'a foot above the robot' mean a foot above the robot's maximum envelope?

About a foot above the J2-J3 (elbow) link on a Fanuc R2000ib/165F when all joints are at their zero positions. It will have DCS though, so at least I can put a DCS box around the cable tray.

Even with DCS, I am going to recommend to our higher ups we get an expert opinion, or at the very least get the customer's safety department to sign off on this.

[Servo]

If the company signs a waiver, doesn't that only mean that the company wont sue you? If an injury occurs based on a hazard that you have identified, then the company signing a waiver would not keep the injured, or their family from suing you, would it?

I'm certainly not qualified to give legal advice, I'm just trying to ask some provocative questions, in order to help you think this through.

Good luck,
Servo