I'm looking for some ideas. We have a Yushin gantry robot that has a rather large EOAT (about 14"x20") that picks an array of inserts (12 at a time). The inserts are staged on trays by an operator, the trays pushed into place and locked. There is a substantial opening (about 20" wide x 4-6" tall) which the operators can reach their arm in the cell, and the robot picks the insert right at that opening. The integrator obviously didn't think out the safety hazards on this one (it was installed about 2015, before I worked here). The Yushin is single channel safety.
I have added guard doors to block this opening while the robot tends, but am unsure as to the best, yet somewhat cost effective method into ensuring the guards are in the down position when the robot is tending. I was thinking of adding locking interlocks, but don't know the best method to tie into the existing safety circuitry (there is only 1 input). Any good suggestions? I was somewhat thinking numerous limit switches, but that will become very cumbersome.
Also note: the Yushin doesn't have a "teach mode' per say, so if the fence is open, you cannot move the robot in any way, plus it kills all 24 volt power (even to signal switches). The tray areas need to be accessible to pull trays out and push them in.