Fundamentals of mechatronics

A: Swapped A/B channels flip the inferred direction right when the controller is most sensitive, so the loop pushes the motor the wrong way at low speed and you see hunting plus current spikes. Insulation breakdown can give torque ripple, but it doesn't explain a sign change in feedback. Low PWM frequency explains noise and some ripple, yet the loop would still converge with low gains. Excess stiction does cause windup, but you'd see a delayed breakaway, not continuous oscillation around zero.

A: Dropping the contactor removes mechanical motion, not stored or supplied electrical energy inside the cabinet, so shock risk stays. Restart risk is handled by the safety relay reset logic, not by the E‑stop itself. Winding temperature falls once power is removed, so overheating isn't the concern here. Encoder reference loss is a functional issue, not a safety hazard addressed by an E‑stop.

A: A 12‑bit converter has 2^12 codes, so the step is full‑scale divided by 4096. The 11‑bit argument mixes ENOB with ideal resolution. Dividing by 4000 is a decimal shortcut that looks tidy but shifts every threshold. Halving the value comes from double‑counting endpoints, which doesn't match how ADC codes are defined.

A: Dashed lines on P&IDs typically separate instrumentation signals from process piping. Redundant tubing would still be shown as solid process lines. Wireless links are called out explicitly with notes or symbols. Temporary hookups belong in commissioning sketches, not the issued P&ID.