A new method of designing multi-loop pid controllers is presented in this paper. By using the generalized imc-pid method for multi-loop systems, the optimization problem involved in finding the pid parameters is effic...
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A new method of designing multi-loop pid controllers is presented in this paper. By using the generalized imc-pid method for multi-loop systems, the optimization problem involved in finding the pid parameters is efficiently simplified to find the optimum closed-loop time constant in a reduced search space. A weighted sum Mp criterion is proposed as a performance cost function to cope with both the performance and robustness of a multi-loop control system. Several illustrative examples are included to demonstrate the improved performance of the multi-loop pid controllers obtained by the proposed design method.
Most chemical processes are basically multiple input/ multiple output (MIMO) systems. Despite considerable work on advanced multivariable controllers for MIMO sys- tems, multiloop proportional-integral-derivative (pid...
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Most chemical processes are basically multiple input/ multiple output (MIMO) systems. Despite considerable work on advanced multivariable controllers for MIMO sys- tems, multiloop proportional-integral-derivative (pid) con- trollers remain the standard for many industries because of their adequate performance with most simple, failure toler- ant, and easy to understand structure. In a multiloop system, once a control structure is xed, control performance is then determined mainly by tuning each multiple single-loop pid controller. However, because the interactions that exist be- tween the control loops make the proper tuning of the multiloop pid controllers quite difcult, only a relatively few tuning methods are available to the multiloop pid controllers and most of them require nonanalytical forms with complex iterative steps (Loh et al., 1993; Luyben, 1986; Skogestad and Morari, 1989). The analytical tuning rule is very attractive, with respect to its practicality, but the mathematical complexity attributed to the loop interactions has mainly prevented the analytical approach to the mul- tiloop systems. In this article, we propose an analytical design method for the multiloop pid controllers to give desired closed-loop responses by extending the generalizedimcpidmethod for single input/single output (SISO) systems (Lee et al., 1998) to MIMO systems. Simple but efcient tuning rules are obtained for general process models by using the fre- quency-dependent property of the closed-loop interactions.
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