Which common electrical fault can cause intermittent robot motion, and how do you troubleshoot?

• A. Controller failure
• B. Faulty or loose I/O wiring; check cables, connectors, shield grounding, measure continuity, verify safety circuits
• C. Sensor misalignment
• D. Power supply overload

Answer: (B)

Intermittent robot motion is most often traced to unreliable I/O connections. The I/O wiring carries the signals that start, stop, enable, and coordinate safety interlocks, as well as the feedback from sensors and actuators. When connections are loose, corroded, or damaged, signals can randomly switch or fail to register, producing sporadic motion or sudden stops as the controller sees conflicting or incomplete data. Proper shield grounding is also crucial because EMI from drives and motors can couple into I/O lines and create false readings if the shield isn’t bonded correctly.

To troubleshoot, start with a careful physical inspection of all I/O cables and connectors. reseat and wiggle connections to see if motion behavior changes, look for cracked insulation, crushed cables, or terminal over-tightening. Check that shield grounds are bonded to the chassis and that the shield isn’t left floating or creating a ground loop. Measure continuity across each wire with a multimeter and verify that the wiring from the controller to I/O modules, sensors, and safety devices is intact and of correct gauge. Confirm safety circuits are wired correctly and functioning, including emergency stops and interlocks, since a fault in these can block motion intermittently. If possible, substitute known-good cables or connectors to isolate the issue, and test signals in diagnostic mode to observe inputs and outputs in real time. The reliability of motion hinges on solid, noise-free I/O wiring and properly connected safety circuits.