A direct method for multi-loop PI/PID controller design

Analytical decoupling control strategy using a unity feedback control structure for MIMO processes with time delays

A simple two-by-two model for a boiler-turbine unit is demonstrated in this paper. The model can capture the essential dynamics of a unit. The design of a coordinated controller is discussed based on this model. A PID control structure is derived, and a tuning procedure is proposed. The examples show that the method is easy to apply and can achieve acceptable performance.

https://www.matlabi.ir/wp-content/uploads/bank_papers/g_paper/g101_Matlabi.ir_Tuning%20of%20PID%20controllers%20for%20boiler-turbine%20units.pdf

Tuning of PID controllers for boiler-turbine units

In this paper, a robust controller design method is first formulated to deal with both performance and robust stability specifications for multivariable processes. The optimum problem is then dealt with using a loop-shaping H∞ approach, which gives a sub-optimal solution. Then a PID approximation method is proposed to reduce a high-order controller. The whole procedure involves selecting several parameters and the computation is simple, so it serves as a PID tuning method for multivariable processes. Examples show that the method is easy to use and the resulting PID settings have good time-domain performance and robustness.

http://www.ece.ualberta.ca/~marquez/papers/tan_ajc02.pdf

Robust Controller Design And Pid Tuning For Multivariable Processes

Brief Identification and control of open-loop unstable processes by relay methods

Underlying algorithms for designing multivariable decoupling and multiloop PI/PID controllers in a sequential fashion are addressed. A single-loop technique, composed of biased relay identification schemes and tuning formulae leading to the minimum weighted integral of square error, is developed to tune each loop in the predetermined sequence of loop closing. The proposed tuning technique is appropriate for a wide range of process dynamics in a multivariable environment. A method is then proposed to design decouplers to compensate for the effect of interactions and tune the resultant weakly interacting, single-loop PI/PID controllers sequentially. The decouplers, together with the single-loop controllers, constitute the multivariable decoupling controller. If the interactions are not significant, multiloop PI/PID controllers, which do not incorporate decouplers, could be employed. Simulation and comparative results are shown for one 2 × 2 and one 3 × 3 multivariable system from the literature. Despite its...

Sequential design method for multivariable decoupling and multiloop PID controllers

A new autotuning method, based on an identification^procedure under P, PI or PID feedback, has been developed to tune PID controllers automatically. The process is identified as a second-order plus dead-time model. Simple algorithms for tuning P, PI and PID controllers are proposed to meet desired specifications on dominant pole placement. IMC-PID controller settings are also provided based on the resulting model. The method can be applied when initial PID settings are required or the settings need to be adapted to changing conditions. A simulation study demonstrates the validity and self-tuning capability of the method for a wide variety of process dynamics.

A new autotuning method with specifications on dominant pole placement

This paper addresses the identification of models using multiple sinusoidal forcing subject to practical difficulties such as unknown initial states, offsets, slow and periodic disturbances, noise, and unknown model structures. A linear regression equation is derived by integrating the system equation excited by a single sinusoid and extended to the case of concurrent multiple sinusoids. The regression equation can be used to estimate the model parameters including time delay in a least-squares fashion. A simple scheme based on the condition number of the matrix formed by the regression vector is presented to infer the best model order. Two-stage sinusoidal testing, represented as two sets of sinusoids applied sequentially, is then developed to generate response data that are informative enough to deal with the aforementioned identification difficulties. This requires only the application of the regression equation for concurrent multiple sinusoids modified in a clever and sequential manner.

Robust identification of continuous parametric models based on multiple sinusoidal testing under slow or periodic disturbances

Stabilizability and identification of systems with one or two unstable poles is addressed. Two limit points of conditional stability are characterized using closed-loop dynamics with a relay and a novel nonlinear element. An algorithm is developed to analyze information from the resultant stable limit cycles in the process input and output. An easily tuned cascade PID control structure is then proposed to stabilize the system and achieve desirable performance. The proposed autotuning technique is tested with good results on a wide variety of unstable systems.

Shing Jia Shiu

Papers

Sequential design method for multivariable decoupling and multiloop PID controllers

A new autotuning method with specifications on dominant pole placement

Robust identification of continuous parametric models based on multiple sinusoidal testing under slow or periodic disturbances

Automatic tuning of systems with one or two unstable poles