Pid Auto Tuning Procedure

09.01.2021

Pid auto tuning HI, As i promised here is the rest pdf file very very nice thing i have made this and using it regards Fragrance 2 members found this post helpful. Oct 01, 2006 A recent survey of Control Engineering subscribers who buy or specify loop controllers indicted that a user-initiated auto-tuning function is the most important feature of a PID controller behind the PID algorithm itself and the ability to communicate with external devices (CE, July 2005, “Loop Controllers: Lone Logic is More Connected”). Aug 03, 2003 Also some of the best PID controllers claim a 'continuous tune' procedure that is always readjusting the PID constants in order to have a good control even when some external parameters vary (like external temperature, internal load, etc). This look like more close to a robust control system based on diferent control rules than PID. PID Tuning is used to Monitor and Tune PID Loops within a process. The PID Tuning window shown below charts the Loop Variables when the Minor Loops is selected (Item a) and allows for Manual or Auto Tune of each Loop.

The Ziegler–Nichols tuning method is a heuristic method of tuning a PID controller. It was developed by John G. Ziegler and Nathaniel B. Nichols. It is performed by setting the I (integral) and D (derivative) gains to zero. The 'P' (proportional) gain, ${displaystyle K_{p}}$ is then increased (from zero) until it reaches the ultimate gain ${displaystyle K_{u}}$ , which is the largest gain at which the output of the control loop has stable and consistent oscillations; higher gains than the ultimate gain ${displaystyle K_{u}}$ have diverging oscillation. ${displaystyle K_{u}}$ and the oscillation period ${displaystyle T_{u}}$ are then used to set the P, I, and D gains depending on the type of controller used and behaviour desired:

Ziegler–Nichols method^[1]
Control Type	${displaystyle K_{p}}$	${displaystyle T_{i}}$	${displaystyle T_{d}}$	${displaystyle K_{i}}$	${displaystyle K_{d}}$
P	${displaystyle 0.5K_{u}}$	–	–	–	–
PI	${displaystyle 0.45K_{u}}$	${displaystyle T_{u}/1.2}$	–	${displaystyle 0.54K_{u}/T_{u}}$	–
PD	${displaystyle 0.8K_{u}}$	–	${displaystyle T_{u}/8}$	–	${displaystyle K_{u}T_{u}/10}$
classic PID^[2]	${displaystyle 0.6K_{u}}$	${displaystyle T_{u}/2}$	${displaystyle T_{u}/8}$	${displaystyle 1.2K_{u}/T_{u}}$	${displaystyle 3K_{u}T_{u}/40}$
Pessen Integral Rule^[2]	${displaystyle 7K_{u}/10}$	${displaystyle 2T_{u}/5}$	${displaystyle 3T_{u}/20}$	${displaystyle 1.75K_{u}/T_{u}}$	${displaystyle 21K_{u}T_{u}/200}$
some overshoot^[2]	${displaystyle K_{u}/3}$	${displaystyle T_{u}/2}$	${displaystyle T_{u}/3}$	${displaystyle 0.666K_{u}/T_{u}}$	${displaystyle K_{u}T_{u}/9}$
no overshoot^[2]	${displaystyle K_{u}/5}$	${displaystyle T_{u}/2}$	${displaystyle T_{u}/3}$	${displaystyle (2/5)K_{u}/T_{u}}$	${displaystyle K_{u}T_{u}/15}$

The ultimate gain ${displaystyle (K_{u})}$ is defined as 1/M, where M = the amplitude ratio, ${displaystyle K_{i}=K_{p}/T_{i}}$ and ${displaystyle K_{d}=K_{p}T_{d}}$ .

These 3 parameters are used to establish the correction ${displaystyle u(t)}$ from the error ${displaystyle e(t)}$ via the equation:

{displaystyle u(t)=K_{p}left(e(t)+{frac {1}{T_{i}}}int _{0}^{t}e(tau ),dtau +T_{d}{frac {de(t)}{dt}}right)}

which has the following transfer function relationship between error and controller output:

{displaystyle u(s)=K_{p}left(1+{frac {1}{T_{i}s}}+T_{d}sright)e(s)=K_{p}left({frac {T_{d}T_{i}s^{2}+T_{i}s+1}{T_{i}s}}right)e(s)}

Evaluation[edit]

The Ziegler–Nichols tuning (represented by the 'Classic PID' equations in the table above) creates a 'quarter wave decay'. This is an acceptable result for some purposes, but not optimal for all applications.

This tuning rule is meant to give PID loops best disturbance rejection.^[2]

It yields an aggressive gain and overshoot^[2] – some applications wish to instead minimize or eliminate overshoot, and for these this method is inappropriate. In this case, the equations from the row labelled 'no overshoot' can be used to compute appropriate controller gains.

References[edit]

^Ziegler, J.G & Nichols, N. B. (1942). 'Optimum settings for automatic controllers'(PDF). Transactions of the ASME. 64: 759–768.Cite journal requires journal= (help)
^ ^a^b^c^d^e^fZiegler–Nichols Tuning Rules for PID, Microstar Laboratories

Bequette, B. Wayne. Process Control: Modeling, Design, and Simulation. Prentice Hall PTR, 2010. [1]
Co, Tomas; Michigan Technological University (February 13, 2004). 'Ziegler–Nichols Closed Loop Tuning'. Retrieved 2007-06-24.

External links[edit]

Retrieved from 'https://en.wikipedia.org/w/index.php?title=Ziegler–Nichols_method&oldid=949638647'

PID tuning is the process of finding the values of proportional, integral, and derivative gains of a PID controller to achieve desired performance and meet design requirements.

PID controller tuning appears easy, but finding the set of gains that ensures the best performance of your control system is a complex task. Traditionally, PID controllers are tuned either manually or using rule-based methods. Manual tuning methods are iterative and time-consuming, and if used on hardware, they can cause damage. Rule-based methods also have serious limitations: they do not support certain types of plant models, such as unstable plants, high-order plants, or plants with little or no time delay.

Auto tune microphone for computer. You can automatically tune PID controllers to achieve the optimal system design and to meet design requirements, even for plant models that traditional rule-based methods cannot handle well.

For more information, see Control System Toolbox™ for use with MATLAB^® and Simulink^®.

Pid Tuning Methods

An automated PID tuning workflow involves: