Working principle of speed sensor

Most of them output pulse signals (approximately sine waves or rectangular waves). There are two methods for measuring the speed of pulse signals: frequency integration method (also known as F/V conversion method, whose direct result is voltage or current), and frequency operation method (whose direct result is digital).
In automation technology, there are many measurements of rotational motion speed, and linear motion speed is often indirectly measured through rotational speed. A DC tachometer generator can convert rotational speed into electrical signals. The speedometer requires a linear relationship between the output voltage and the rotational speed, and requires a steep output voltage with good time and temperature stability.
Speed measuring machines can generally be divided into two types: DC and AC. Rotating speed sensors come into direct contact with moving objects. When a moving object comes into contact with a rotating speed sensor, friction drives the roller of the sensor to rotate. The rotating pulse sensor installed on the roller sends out a series of pulses. Each pulse represents a certain distance value, allowing for the measurement of linear velocity. Electromagnetic induction type, a gear is installed on the rotating shaft, with an electromagnetic coil on the outer side. Rotation is due to the clearance between the teeth passing through, obtaining a square wave voltage change, and then calculating the speed.
The rotary speed sensor has no direct contact with the moving object. The blade edge of the impeller is covered with a reflective film, which drives the impeller to rotate when the fluid flows. The optical fiber transmits the reflection once every rotation of the impeller, generating an electrical pulse signal. The speed can be calculated based on the number of detected pulses.