The rod-type displacement sensor uses a potentiometer-type displacement sensor, which converts mechanical displacement into a resistance or voltage output that is linear or has an arbitrary function relationship with it through a potentiometer element. Ordinary linear potentiometers and circular potentiometers can be used as linear displacement and angular displacement sensors, respectively. However, the potentiometer designed for the purpose of measuring displacement requires a definite relationship between displacement change and resistance change. The movable brush of the potentiometer-type displacement sensor is connected to the object to be measured, and the displacement of the object causes the resistance change at the moving end of the potentiometer. The change in resistance reflects the magnitude of the displacement, and the increase or decrease in resistance indicates the direction of the displacement. Usually, a power supply voltage is passed through the potentiometer to convert the resistance change into a voltage output. The traditional wire-type displacement sensor has a step-shaped output characteristic because its resistance changes in turns as a step when its brush moves. If this displacement sensor is used as a displacement feedback element in a servo system, an excessive step voltage will cause system oscillation. Therefore, the resistance value per turn should be minimized in the production of the potentiometer. At the same time, another major disadvantage of the potentiometer sensor is that it is easy to wear, has poor resolution, low resistance, and poor high-frequency characteristics, which leads to a decrease in measurement accuracy.

Its advantages are: simple structure, large output signal, easy to use, and low price.