Archive | Automatic Controls and Robotics

ISA Automatic Controls and Robotics Division

Thermal Chamber

Modified Smith predictor design for periodic disturbance rejection

Abstract: In this paper, a modified Smith predictor control scheme is proposed for periodic disturbance rejection in both stable and unstable processes with time delay. Without affecting the superior setpoint response of Smith predictor control, the regulation performance under periodic disturbance can be enhanced significantly by the proposed design. Meanwhile, the asymptotical rejection for non-periodic […]

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Fig. 1. IMC control strategy.

Tuning PI controllers for stable processes with specifications on gain and phase margins

Abstract: In industrial practice, controller designs are performed based on an approximate model of the actual process. It is essential to design a control system which will exhibit a robust performance because the physical systems can vary with operating conditions and time. Gain and phase margins are well known parameters for evaluating the robustness of […]

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Fig. 1. Basic process structure.

Flexible-structure control: A strategy for releasing input constraints

Abstract: In this paper output unreachability under input saturation phenomenon is studied: under a large disturbance or setpoint change, the process output may never reach the set point even when the manipulated variable has driven to saturation. The process output can be brought back to the set point only by activating an auxiliary manipulated variable. […]

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Fig. 1. Nomenclature of line segments.

A simple numerical procedure for estimating nonlinear uncertainty propagation

Abstract: Accurately determining the effect of the propagation of uncertainty in nonlinear applications can be awkward and difficult. The Monte Carlo approach requires statistically significant numbers of function evaluations (typically 105 or more) and analytical methods are intractable for all but the simplest cases. This paper derives and demonstrates a method to estimate the propagation […]

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Fig. 1. Configuration of the cascade control system.

Auto-tuning of cascade control systems

Abstract: In this paper, a novel auto-tuning method for a cascade control system is proposed. By employing a simple relay feedback test, both inner and outer loop model parameters can be simultaneously identified. Consequently, well-established proportional-integral-derivative (PID) tuning rules can be applied to tune both loops. Compared with existing methods, the new method is simpler […]

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Fig. 1. Structure of the single-prediction controller.

Predictive feedback control

Abstract: In this work a new method for designing predictive controllers for linear single-input/single-output systems is presented. It uses only one prediction of the process output J time intervals ahead to compute the correspondent future error. Then, the predictive feedback controller is defined by introducing a filter which weights the last w predicted errors. In […]

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Fig. 1. The Merrick weigh belt feeder.

Self-tuning adaptive control for an industrial weigh belt feeder

Abstract: An industrial weigh belt feeder is used to transport solid materials into a manufacturing process at a constant feedrate. It exhibits nonlinear behavior because of motor friction, saturation, and quantization noise in the measurement sensors. To overcome the nonlinearities, a simple yet effective method of controller autotuning, an indirect self-tuning regulator, was designed and […]

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George Buckbee

What Your DCS Knows But Won’t Tell You

This session is in the Control Performance Track: Manufacturing Intelligence Presented By: Mr. George Buckbee, ExperTune, Inc. Read Bio Abstract: Your DCS is keeping secrets from you.  The distributed control system and the data historian have a huge amount of data from your plant.  But they are not telling you the most important secrets that lie within. […]

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Fig. 1. The Smith predictor control scheme.

Autotuning of a new PI-PD Smith predictor based on time domain specifications

Abstract: The paper extends a recent work on a modified PI-PD Smith predictor, which leads to significant improvements in the control of processes with large time constants or an integrator or unstable plant transfer functions plus long dead time for reference inputs and disturbance rejections. Processes with high orders or long time delays are modeled […]

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