Closed Loop vs Open Loop

One of the things I love is to understand how systems work. ¬†From FedEx sorting, to gas station fuel pumps, to nuclear weapons (which are actually a lot simpler than you might think). One of the things I’ve learned is that systems can be divided into two classes: closed loop and open loop. An open loop system is a system with no feedback; it just happily runs along doing what it is told to do with no real indicator of success. It just assumes everything is hunky dory. While these systems are usually cheap to build and very reliable, they can cause problems. For example, I spent a small amount of time at a grape vineyard assisting with the grape juice processing during harvest season. There were 8 different machines the grapes went through before processing was finished. There was one machine whose job is to crack open the grapes by crushing them just a little. This was the first real step, and it was the main bottleneck in processing the grapes into grape juice. There was a large conveyor belt that fed this machine, and if the guys putting grapes on the conveyor belt were too fast, the hopper on the crusher would fill up and grapes would start raining down inside the building. It was a non-profit facility run by volunteer labor, so the quality of the labor was somewhat random. Sometimes you would get over-eager people that no matter what you told them would keep dumping grapes on the conveyor until finally, to their dismay, you just turned off the electricity to their equipment so they...