What kind of regulator is used for instrument valve

What kind of regulator is used for instrument valve
Instrument valve adopts analog signal regulator, also known as analog instrument valve. It determines the deviation between the measured value and the given value in the analog form of the controlled object parameters, and generates the analog output signal according to a certain regulation law to drive the actuator to eliminate the deviation, so as to keep the controlled parameters near the given value or change according to the predetermined law. In the automation instrument, the instrument valve is often used to synthesize the output signal of the detection instrument in order to control the production process. The regulated parameters include temperature, pressure, flow rate, liquid level, composition, etc.