Yeah. Articles like this one is why I started following HN religiously. I would understand "analog computer" as some form of a proportional controller - like PI

Yeah. Articles like this one is why I started following HN religiously. I would understand "analog computer" as some form of a proportional controller - like PID, but with ID terms set to 0: https://en.m.wikipedia.org/wiki/PID_controller https://en.m.wikipedia.org/wiki/PID_controller The sensor must be able to somehow measure how fast the target is moving relatively to the center of the sensor area. The proportional controller then sets the fins in a slightly exaggerated fashion.