When troubleshooting a robot system, what type of multimeter measurement helps identify a floating ground?

When troubleshooting a robot system, measuring the AC voltage between the equipment grounding conductor (ground wire) and a known good earth ground can help identify a floating ground. A floating ground occurs when the grounding system is not properly connected to earth, resulting in a voltage potential between the grounding conductor and the true earth ground. This voltage potential can introduce noise and instability into the electrical system, leading to erratic robot behavior or sensor malfunctions. To perform this measurement, set the multimeter to measure AC voltage, connect one lead to the equipment grounding conductor (typically the green or green/yellow wire) at the robot controller or other relevant component, and connect the other lead to a known good earth ground, such as a grounded metal water pipe or a grounding rod driven into the earth. A reading significantly above 0V AC indicates a floating ground. For example, a reading of 5V AC or higher suggests that the grounding system is not properly connected to earth and is susceptible to noise and interference. Correcting a floating ground involves ensuring a solid, low-impedance connection between the equipment grounding conductor and the earth ground. It is important to ensure power is removed and LOTO procedures are followed before checking ground connections.