A Design Method for Modified Smith Predictors for Non-Minimum-Phase Time-Delay Plants with Multiple Feedback-Connected Time-Delays

2010 ◽  
Vol 36 ◽  
pp. 253-262 ◽  
Author(s):  
Iwanori Murakami ◽  
Nghia Thi Mai ◽  
Kou Yamada ◽  
Takaaki Hagiwara ◽  
Yoshinori Ando ◽  
...  
Keyword(s):  
Steady State ◽  
Time Delay ◽  
Time Delays ◽  
Large Time ◽  
Design Method ◽  
Smith Predictor ◽  
Minimum Phase ◽  
Effective Time ◽  
Phase Time ◽  
Step Disturbance

In this paper, we examine a design method for modified Smith predictors for non-minimum-phase time-delay plants with multiple feedback-connected time-delays. The Smith predictor is proposed by Smith to overcome time-delay and known as an effective time-delay compensator for a plant with large time-delay. The Smith predictor by Smith cannot be used for plants having an integral mode, because a step disturbance will result in a steady state error. Several papers considered the problem to design modified Smith predictors for unstable plants. However, no paper examines a design method for modified Smith predictors for non-minimum-phase time-delay plants with multiple feedback-connected time-delays. In this paper, we examine a design method for modified Smith predictors for non-minimum-phase time-delay plants with multiple feedback-connected time-delays.

scholarly journals A Design Method for Smith Predictors for Minimum-Phase Time-Delay Plants

1970 ◽  
Vol 1 (2) ◽  
pp. 100-107
Author(s):  
Kou Yamada ◽  
Nobuaki Matsushima
Keyword(s):  
Time Delay ◽  
Time Delays ◽  
Large Time ◽  
Design Method ◽  
Smith Predictor ◽  
Minimum Phase ◽  
Effective Time ◽  
Phase Time ◽  
Modified Smith Predictor ◽  
Uniform Manner

In this paper, we examine a design method for a modified Smith predictor for minimum-phase timedelay plants. The modified Smith predictor is well known as an effective time-delay compensator for a plant with large time delays, and several papers on the modified Smith predictor have been published. However, the parameterization of all stabilizing modified Smith predictors has not been obtained. If this can be obtained, we can express existing proposals for modified Smith predictors in a uniform manner, and the modified Smith predictor can be designed systematically. The purpose of this paper is to propose the parameterization of all stabilizing modified Smith predictors for minimum-phase time-delay plants. The control characteristics of the control system using the parameterization of all stabilizing modified Smith predictors are also given. Finally, numerical examples for stable plants and unstable plants are illustrated to show the effectiveness of the proposed parameterization of all stabilizing modified Smith predictors.

Smith predictor based fractional-order integral controller for robust temperature control in a steel slab reheating furnace

2019 ◽  
Vol 41 (16) ◽  
pp. 4521-4534 ◽  
Author(s):  
Vicente Feliu-Batlle ◽  
Raul Rivas-Perez
Keyword(s):  
Time Delay ◽  
Fractional Order ◽  
Temperature Control ◽  
Pid Controller ◽  
Large Time ◽  
Smith Predictor ◽  
Reheating Furnace ◽  
Steel Slab ◽  
Integral Controller ◽  
Fractional Order Integral

In this paper, a new strategy for robust control of temperature in a steel slab reheating furnace with large time delay uncertainty based on fractional-order controllers combined with a Smith predictor is proposed. A time delay model of the preheating zone of this process is used, obtained from an identification procedure applied in a real industrial furnace. It is shown that this process experiences very large time delay changes. A fractional-order integral controller embedded in a Smith predictor structure (FI-SP) is designed, which is robust to changes in such time delay. Simulated results of a standard Proportinal Integral Derivative (PID) controller, a PID controller embedded in a Smith predictor and the proposed FI-SP controller are compared. Six performance indexes have been used in this comparison. The analysis of these indexes shows that the designed FI-SP controller exhibits the most robust behavior (lowest indexes averaged in all the range of time delay variation) for ranges that include large time delays. Then the robustness features of the FI-SP controller outperform the other integer order controllers in the time responses both to set-point changes and to step disturbances. Therefore, this controller guarantees the best accuracy of temperature control. The designed FI-SP guarantees system stability and robust performance for a high range of plant time delay uncertainties.

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