A robot shows unexpected jerk during motion. Which of the following is a plausible cause?

• A. Vision sensor camera dirty.
• B. Low battery in laptop.
• C. Overcooling of the controller only.
• D. Encoder misalignment, mechanical backlash, loose mounts, controller parameters, software updates, improper path.

Answer: (D)

Jerk, a sudden change in acceleration, usually comes from issues that directly affect the motion command or the mechanical transmission. The most plausible cause is problems in the drive system and control tuning: encoder misalignment can give incorrect position feedback, leading the controller to make abrupt corrections; mechanical backlash or loose mounts introduce play and vibrations that translate into sudden velocity changes; controller parameters or recent software updates can make the system respond too aggressively or change trajectory handling, causing sharp transitions in motion; and an improper path with sharp corners or abrupt speed changes forces the actuators to accelerate or decelerate quickly. Together, these factors create non-smooth motion that shows up as jerk.

Dirty vision sensors or a low laptop battery are less likely to cause real mechanical jerk. A dirty camera affects perception and may lead to erroneous feedback in vision-based loops, but it doesn’t directly induce the mechanical stiffness or rapid command changes that cause jerk. A low battery might influence computation or performance indirectly, but it isn’t a direct jerk source. Overcooling the controller wouldn’t typically produce jerk; it would more likely reduce performance or lead to throttling if anything.