The guages should be easily visible during inspection. They should also be easily visible when someone is working near the robot so they can tell if the system has pressure in it or not.
“Easily” means that you shouldn’t have to move wires, plates, arms, bumpers or whatever. You also shouldn’t have to crawl under the robot or stick your head in some dangerous position to read them.
As an inspector, I’ve always appreciated teams that made it easy to check their pneumatic system.