Useful tips: How to understand PID parameter tuning?

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PID are the three basic control laws of regulators, namely proportional control (P), integral control (I), and derivative control (D). PID parameters refer to the proportional gain (δ), integral time (Ti), and derivative time (Td), which respectively represent the intensity of proportional control, integral control, and derivative control. Tuning the PID parameters involves adjusting these three values, δ, Ti, and Td, in order to achieve the best control performance for the control loop (for example, a 4:1 attenuation in the transition process). This article was originally published on the WeChat official account “Automation Classroom”. PID parameter tuning can be simply summarized as follows: Proportional control functions like an amplifier, which amplifies the difference between the measured value and the set value for output. The degree of amplification depends on the proportional gain setting; the higher the proportional gain, the lower the amplification factor. Integral control, also known as a reset regulator, continues to act cumulatively as long as there is a deviation, until that deviation is eliminated. The speed at which the deviation is eliminated depends on the length of the integration time; a longer integration time results in a slower elimination of the deviation. The output change resulting from differential regulation is proportional to the rate of change of the input deviation. The faster the rate of change in the deviation between the measured value and the set value, the stronger the differential effect; moreover, a longer differential time also results in a stronger differential effect. In production process control, integral or differential action is generally not used alone, but rather in conjunction with proportional action. The advantage of proportional control is its fast response and timely regulation, but there is a residual error; to eliminate this error, integral control must be added. The characteristic of the differential control law is that it provides a certain degree of lead control, which helps to suppress system oscillations and enhance stability. It is generally used in situations where the process response is slow and takes a long time, such as in temperature control circuits or for controlling the level in large storage tanks. When the differential effect is added, it results in a combined control action of proportional, integral, and differential actions – that is, PID control. Summary: Proportionality (δ): The greater the proportionality, the weaker the proportional action; the smaller the proportionality, the stronger the proportional action. Integration time (Ti): The longer the integration time, the weaker the integrating effect; the shorter the integration time, the stronger the integrating effect. Differential time (Td): The longer the differential time, the stronger the differential effect; the shorter the differential time, the weaker the differential effect.