Fable
The gatekeeper and the person on the watchtower
Old Sun's automated workshop has two human-machine collaboration models. The first production line is called the "approval line": each product goes from the first process to the last, passing through three manual inspections along the way. Inspectors stand beside the conveyor belt, glance at the product as it passes, and stamp it. Without a manual stamp, the product can't move to the next process.
The second production line is called the "monitoring line": the product flows automatically from start to finish, with no one stopping it midway. But on the second floor of the workshop there is an observation room, where a dispatcher sits in front of a status screen for the entire production line. As long as temperature, speed, and pass rate are within the set range, the dispatcher does nothing. Once an indicator deviates from the preset range, a red light lights up on the screen, and only then does the dispatcher intervene—pausing the line, adjusting parameters, or pulling the abnormal batch out for separate inspection.
The workshop took a large order and had to run two production lines at the same time. A month later, the factory manager compared the data from the two lines. The approval line's output was only forty percent of the monitoring line's, because every process step had to wait for a person to stamp it, and people have times for rest, distraction, and queuing, so the machines had to wait. But the approval line's defect rate was almost zero—every product had passed through human judgment.
The monitoring line had high output, but a problem arose: once a temperature sensor drifted by two degrees, within normal fluctuation range, and the system didn't alarm. After running continuously for three hours, a key dimension of the product was already out of tolerance, but the entire batch passed automated inspection. By the time the dispatcher noticed, a whole batch of defective products had been produced. The dispatcher admitted: during those three hours he had not actively spot-checked the product, just stared at the screen waiting for a red light.
The factory manager laid the experience of the two production lines on the table. The core of the approval line is that a person must say "yes" before release—the person is in the decision path at every step, which is called in the loop. The core of the monitoring line is that a person does not need to intervene at every step, but must patrol regularly and take over when something goes wrong—the person is in a supervisory position outside the loop, which is called on the loop.
The factory manager chose different modes for each scenario. For processes involving safety, compliance, and funding decisions, the approval line was used, with humans in the loop. For high-volume, controllable-risk processes in daily operations, the monitoring line was used, with humans on the loop, but a hard rule was added for dispatchers: they must go to the production line for a random spot check once every hour, and cannot just stare at screens.
Three months later, workshop efficiency went up and quality did not drop. The factory director summed it up in one sentence: for processes that require a person to nod, put the person in the middle of the path. For processes that only require a person to watch, put the person up high, but don't forget to have them come down and walk around regularly.
Later, whenever each new production line was launched, they first spent a week determining which nodes needed stamping and which nodes only needed watching. The old workers called this "define the posts first, then assign the people."