On PID control learning*

Study books on automatic instrumentation; the output of a proportional controller is equal to a multiple of the error. Without an error, there is no output either. Therefore, an error controller must be present in order to generate an output, meaning that residual errors cannot be eliminated. This post was last edited by jujiangliu on 2008-11-7 17:06.]

1. PID (Proportional Integral Differential) control: PID stands for proportional, integral, and differential control, and it is an important control method in automatic control. 2. Methods of implementing PID control: Analog method: An electronic circuit regulator is used; within this regulator, the signal to be monitored is compared with a set value, and the resulting difference is processed by a PID circuit before being sent to the actuator in order to adjust the amount of feed and thus achieve regulation. Digital method: Use a computer to perform PID calculations, convert the results into analog signals, and output them to control the actuator.

It is only after there is a deviation that the ratio becomes relevant

Here is some learning material on PID control; I’m not sure if it will be useful to you. http://bbs.hcbbs.com/post.php?action=newthread&fid=173&extra=page%3D1

How to set PID parameters and adjust them – An introduction to PID control. Currently, the level of industrial automation has become an important indicator of the modernization level of various industries. At the same time, the development of control theory has also gone through

It’s true that proportional control with a remainder term is necessary for it to work, but does it mean there is no output without a remainder term controller? So at steady state, the measured value is the same as the control value, with no error remaining; does this mean the controller has no output at that point? If not, how can the actuator be maintained in the controlled position? For example, if we want to keep the liquid level at 50%, but it suddenly rises to 55%, how will proportional control handle this situation? Does it stop functioning once it reaches a certain value, such as 52%? Keep a certain margin of error?

Put it into practice – find a DCS or a PLC system and practice actually using it

The controller outputs can be position-type or incremental-type. For position control, the PID calculates the accumulation of previous errors and outputs the control amount in its entirety. Incremental type: PID does not accumulate errors; it only calculates the current deviation and outputs the increment of the control amount. Therefore, when the measured value matches the set value, the PID will produce an output; however, the position type still experiences some fluctuations, while the incremental type maintains its output almost consistently. In a previous post, someone shared a comparison between position-type and incremental PID controllers, which might be useful: Comparison between incremental and position-type algorithms: (1) The incremental algorithm does not require accumulation, and the issues related to calculation accuracy that arise from error calculation have less impact on the calculation of the control signal. Position-based algorithms use the accumulation of past errors, which can easily lead to large cumulative errors. (2) The incremental algorithm yields the increment in control, resulting in minimal impact from malfunctions; if necessary, logical judgments can be used to restrict or prohibit that particular output without affecting the operation of the system. The output of a position-based algorithm is the entire output of the control quantity, and malfunction has a significant impact.

I recommend a book to you: New PID Control and Its Applications. If you can’t get it, send me a message and I’ll send it to you.