PID parameter tuning

This post was last edited by liaifeng on 2018-5-11 21:50. Proportional control is for setting timely actions, integral control is for eliminating residual errors, and derivative control is for advance regulation! Generally, proportional control is used first; it depends on whether your system uses setting of the proportional gain or the proportional value. In the case of proportional gain, the higher the value, the weaker the effect. The proportional value operates in a direct proportionality relationship! When the parameters oscillate in an attenuating manner, it is necessary to involve integration; the integration time is inversely proportional to the effect – the longer the time, the weaker the effect! Differential action is not required in every control loop; it is generally used only for parameters such as liquid level where it is necessary to prevent large fluctuations! The differential time is directly proportional to the action! There is also a mnemonic for parameter tuning that can be used as a reference: To find the optimal settings, check values in ascending order. Start with the proportional term, then the integral term, and finally add the derivative term. If the curve oscillates frequently, increase the proportional gain; if the curve wanders around in large swings, decrease the proportional gain. If the curve takes a long time to return to its normal state, reduce the integration time. If the curve’s fluctuations have a long cycle, extend the integration time further. If the oscillation frequency is high, first reduce the derivative term. Large errors lead to slow fluctuations. The differential time should be increased. For the ideal curve, there are two waves – higher at the beginning and lower at the end, in a 4-to-1 ratio. Observe carefully, make adjustments as needed, and conduct thorough analysis; this way, the quality of the adjustments will not be poor. Personally, I think it’s necessary to keep exploring and researching in order to find a method for adjusting the parameters of the device to make it suitable for use! Moreover, I have personally found that after certain operating conditions change, these settings need to be adjusted again specifically for those new conditions!

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