Analog vs. stepper motors in industrial control

In the process of daily life and industrial production control, it is necessary to pay attention to a variety of states in real time, some of which can be described very simply, such as whether a coin is facing up, whether a door is open, whether it is raining today, whether there are workers in the factory asking for leave, etc., can be simply described with or not. But such a description may not be detailed enough, just like the opening and closing of a valve, we only use the two states of open and closed, which is not very good for our monitoring needs. Because the valve is half open and fully open, both are open, and there is no way to distinguish between this description, so the valve opening will be used to describe this problem in the actual control. Especially in the continuous production process, it is often required to collect and control some physical quantities such as voltage, current, pressure, speed, flow, etc., which are continuously changed with time. In the field of control, these physical quantities that change continuously over time are called analog quantities.