Below, a manufacturer of egg beaters explains how the measurement and control modes of an egg beater work. During operation, the mixer’s beaters rotate at high speed, forcing the ingredients to mix thoroughly. The ingredients come into full contact with one another and undergo intense friction, achieving mixing, emulsification, aeration, and the removal of some moisture. Since the viscosity of the ingredients processed by an egg beater is lower than that of ingredients processed by a dough mixer, the egg beater operates at a higher speed—typically ranging from 70 to 270 r/min—and is therefore referred to as a high-speed mixer. Egg beaters are mostly manual, upright devices consisting of a mixer, a container, a drive mechanism, a container lifting mechanism, and a base. As for how they are measured and controlled—as you surely know—measurement and control involve measuring the concentration of the solid-liquid mixture inside the container (i.e., viscosity) and controlling the rotational speed of the drive mechanism. The most common method for measuring viscosity is using an accelerometer. I’m not sure what type of sensor is used here, but if I were designing it, I would definitely use an accelerometer. Based on physics, we know Newton’s Second Law: F = ma. Additionally, the motion of an object varies depending on the viscosity of the liquid—there’s a relatively straightforward relationship between the two. The sensor on the rotating mechanism collects viscosity data and sends it to the controller. Through feedback regulation—typically by transmitting voltage signals to the control unit—the rotational speed is adjusted based on the voltage level. This utilizes the concept of negative feedback from the principles of automatic control.

In simple terms, when the egg beater detects a high concentration, it needs to spin faster; after spinning for a while, once the eggs are mostly beaten, the feedback signal indicates that the concentration has decreased, so the rotational speed is reduced.

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