Which option provides a physical limit to robot movement not relying on software?

• A. Safety fences
• B. Light curtain
• C. Tooling
• D. Mechanical stops

Answer: (D)

A hard, physical limit to motion that doesn’t depend on software is being tested here. Mechanical stops give a fixed boundary for the robot’s travel; when the arm reaches the stop, it cannot move further because there is a tangible obstacle or built-in stop inside the mechanism. This works entirely without any control software deciding to stop.

Safety fences and light curtains are barriers, but they rely on sensing and a safety controller to trigger a stop. If the software or safety system isn’t active, those barriers won’t enforce the stop, so they’re not independent of software. Tooling, while it can affect reach or clearance, isn’t itself a built-in limit to movement. Therefore, the mechanical stops option best fits a physical, software-free limit to movement.