Conference Paper

# A novel method of PID tuning for integrating processes

Inst. of Autom., Shanghai Jiao Tong Univ., China

DOI: 10.1109/CDC.2003.1272549 Conference: Decision and Control, 2003. Proceedings. 42nd IEEE Conference on, Volume: 1 Source: IEEE Xplore

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**ABSTRACT:**A new method for tuning controllers on-line has been developed based on a single experimental test, a step change in controller set point. The set-point response data and analytical formulae are used to calculate model parameters for a first-order plus time delay transfer function. Controller settings can then be calculated using the model parameters and standard controller tuning relations. Simulation results demonstrate that the new method provides good initial values for PID controller settings despite gross modeling errors and unanticipated load disturbances that may occur during the experimental test.AIChE Journal 06/2004; 28(3):434 - 440. · 2.58 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**Chien and Fruehauf proposed the use of a simple integrator/deadtime transfer function to model many chemical processes, particularly those with large time constants. Tyreus and Luyben presented tuning rules that give the optimal reset time and controller gain for proportional−integral (PI) control of this type of process. This paper extends the previous work with PI control to proportional−integral−derivative (PID) controllers. Tighter control is possible with PID control, provided signals are not noisy. Frequency domain methods are used to show that the derivative tuning constant should be set equal to the reciprocal of the ultimate frequency. The controller gain is then set equal to 0.46 times the ultimate gain. This process has unusual dynamic behavior when PID control is used, which makes controller tuning nontrivial. The system exhibits conditional stability: at low controller gains the loop is unstable, and at high controller gains the loop is again unstable. Contrary to conventional tuning, a decrease in gain results in an unexpected decrease in closed-loop damping coefficient over a certain range of controller gains.Industrial & Engineering Chemistry Research - IND ENG CHEM RES. 10/1996; 35(10). - [Show abstract] [Hide abstract]

**ABSTRACT:**A systematic PI and PID tuning method is developed for integrating and unstable processes. The method, based on a maximum peak-resonance specification, leads to simple tuning parameter expressions and is graphically supported by the Nichols chart. The common characteristic of integrating and unstable processes is their open-loop frequency response, with the controller in cascade and has a phase maximum. The controller parameters are adjusted such that this maximum is located on the right-most point of the ellipse, corresponding to the maximum peak resonance on the Nichols chart. This type of processes, making the open-loop frequency-response curve tangent to a specified ellipse, is an efficient method of controlling the overshoot, the stability and the dynamics of the system. Charts that give the optimal peak resonance, according to the ITAE criterion, are given. The results obtained with this method are presented for typical design examples. A comparison of the performances of the proposed design settings with those given by earlier researchers for unstable processes is presentedIEE Proceedings - Control Theory and Applications 10/1996; · 1.05 Impact Factor

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