ASAHIKAWA, Japan — Removing the tiny eyes that pockmark potatoes is dull, repetitive and time-consuming work — perfect, it would seem, for robots in a country where the population is declining and workers are increasingly in short supply.

But it’s not so simple.

When a food processing plant that makes potato salad and stews in Hokkaido, Japan’s northernmost island, tried out a robot prototype designed to remove the potatoes’ eyes, the machine was not up to the task.

The robot’s camera sensors were not sensitive enough to identify every eye. While human hands can roll a potato in every direction, the robot could rotate the vegetables on only one axis, and so failed to dig out many of the blemishes that are toxic to humans. Other perfectly good pieces were carved away.