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Articles 61 - 90 of 94
Full-Text Articles in Controls and Control Theory
Comparison Of Open- And Closed-Loop Process Identification Techniques In The Time-Domain, Tony Kealy, Aidan O'Dwyer
Comparison Of Open- And Closed-Loop Process Identification Techniques In The Time-Domain, Tony Kealy, Aidan O'Dwyer
Conference papers
Abstract: This paper describes seven methods to identify a mathematical model for a real process with a time delay. The process is the Process Trainer, PT326 from Feedback Instruments Limited. Six of the methods use the step response data and one of the methods uses the impulse response data for identification.
Closed Loop Identification Of A First Order Plus Dead Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer
Closed Loop Identification Of A First Order Plus Dead Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer
Conference papers
Abstract -- This paper discusses the estimation of the parameters of a first order plus dead-time process model using the closed-loop step response data of the process under proportional plus integral (PI) control. The proportional gain and the integral time, in the PI controller, are chosen such that the closed-loop step response exhibits an under-damped response. From this response data, five characteristic points are used to determine a second order plus dead-time model and subsequently, the frequency response of the closed-loop system. Knowing the dynamics of the closed-loop system and the dynamics of the controller, the open-loop dynamics of the …
Multiple Model Networks In Non-Linear System Modelling For Control – A Review, Ruiyao Gao, Aidan O'Dwyer
Multiple Model Networks In Non-Linear System Modelling For Control – A Review, Ruiyao Gao, Aidan O'Dwyer
Conference papers
Non-linear processes, by their nature, are non-uniform and invariably require custom designed control schemes to deal with individual characteristics. No general theory deals comprehensively with the wide range of non-linear systems encountered. In an attempt to accurately model non-linear dynamical systems, a wide variety of techniques have been developed such as non-linear auto-regressive moving average with exogeneous inputs (NARMAX) models (Chen and Billings, 1989), Weiner models (Schetzen, 1981), Hammerstein models (Billings and Fakhouri, 1982) and Multiple Layer Perceptron (MLP) neural networks (Narendra and Kannan, 1990). While the accuracy of such models offers a potentially significant improvement over linear models, the …
Model Predictive Control Of Cstr Based On Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Dermot Coyle Professor
Model Predictive Control Of Cstr Based On Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Dermot Coyle Professor
Conference papers
A non-linear predictive controller is presented. It judiciously combines predictive controllers with a local model network utilizing a neural-network-like gating system. It avoids the time consuming quadratic optimization calculation, which is normally necessary in non-linear predictive control. A controller simulation on a Continuous Stirred Tank Reactor (CSTR) case study was shown to be satisfactory both in terms of set point tracking and regulation performance over the entire operating range. Moreover, the inherent integration action in the local predictive controller provides zero static offsets.
Closed Loop Identification Of A First Order Plus Dead-Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer
Closed Loop Identification Of A First Order Plus Dead-Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer
Conference papers
This paper discusses the estimation of the parameters of a first order plus dead-time process model using the closed-loop step response data of the process under proportional plus integral (PI) control. The proportional gain and the integral time, in the PI controller, are chosen such that the closed-loop step response exhibits an under-damped response. From this response data, five characteristic points are used to determine a second order plus dead-time model and subsequently, the frequency response of the closed-loop system. Knowing the dynamics of the closed-loop system and the dynamics of the controller, the open-loop dynamics of the process can …
Comparison Of Open And Closed Loop Process Identification Techniques In The Time Domain, Tony Kealy, Aidan O'Dwyer
Comparison Of Open And Closed Loop Process Identification Techniques In The Time Domain, Tony Kealy, Aidan O'Dwyer
Conference papers
This paper describes seven methods to identify a mathematical model for a real process with a time delay. The process is the Process Trainer, PT326 from Feedback Instruments Limited. Six of the methods use the step response data and one of the methods uses the impulse response data for identification.
Discrete-Time Velocity-Based Multiple Model Networks, Ruiyao Gao, Seamus Mcloone, Eugene Dermot Coyle Professor
Discrete-Time Velocity-Based Multiple Model Networks, Ruiyao Gao, Seamus Mcloone, Eugene Dermot Coyle Professor
Conference papers
The velocity-based local model (LM) network is a novel modelling approach that overcomes the lack of interpretability associated with the conventional LM network technique. The global dynamics of the nonlinear network are directly related to the underlying sub-model dynamics. Thus, the velocity-based network is ideally suited to the development of local controller (LC) networks. Furthermore, the local models are continuous-time, velocity-based and linear, providing continuity with established linear theory. To date, research has focused on the continuous-time version of the velocity-based network. The application of digital computer is widely popular in the field of control and, therefore, this paper develops …
A Non-Linear Pid Controller For Cstr Using Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Dermot Coyle Professor
A Non-Linear Pid Controller For Cstr Using Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Dermot Coyle Professor
Conference papers
The basic PID controllers have difficulty in dealing with problems that appear in complex non-linear processes. This paper presents a practical non-linear PID controller that deals with these non-linear difficulties. It utilises a local model (LM) network, which combines a set of local models within an artificial neural network structure, to adaptively characterise the process non-linearity. Then a local controller network is formulated through a gating system deduced from the LMN to handle the non-linearity. A continuous stirred tank reaction (CSTR) case study illustrates the practicality of this method in the modelling and control of non-linear processes. PID controllers are …
Time Delay Estimation In Signal Processing Applications: An Overview, Aidan O'Dwyer
Time Delay Estimation In Signal Processing Applications: An Overview, Aidan O'Dwyer
Conference papers
An extensive though scattered literature exists on the estimation of time delays in signal processing applications. However, it is possible to identify themes that are common to many of the available techniques. The intention of this paper is to provide a framework against which the literature may be viewed. In addition, original work on gradient based time delay estimation is described.
Towards An Expert System Approach For Pi Controller Design Of Delayed Processes, Michael Feeney, Aidan O'Dwyer
Towards An Expert System Approach For Pi Controller Design Of Delayed Processes, Michael Feeney, Aidan O'Dwyer
Conference papers
This paper will discuss the compensation of first order lag plus time delay (FOLPD) processes using PI controllers whose parameters are specified using appropriate tuning rules. The gain margin and phase margin of the compensated system, as the ratio of time delay to time constant of the process varies, are calculated for each tuning rule and an expert system is used to recommend a tuning rule for user defined requirements.
Comparison Of Two B-Polynomial Methods: Application To The Identification Of Time Delayed Processes, Ruiyao Gao, Aidan O'Dwyer
Comparison Of Two B-Polynomial Methods: Application To The Identification Of Time Delayed Processes, Ruiyao Gao, Aidan O'Dwyer
Conference papers
An extensive literature exists on the estimation of the model parameters of time delayed processes. The objective of this paper is to review the main B-polynomial approaches to the delay estimation problem. More specifically, two algorithms are discussed and compared theoretically and in simulation. The algorithms involve various procedures to assess how the model relates to the observed data, to a priori knowledge, and to the algorithms’ intended use. Simulation results indicate that both the algorithms can suitably identify the model parameters, including the time delay. This paper also discusses advantages and disadvantages of the methods and gives some guidelines …
Pi And Pid Controller Tuning Rule Design For Processes With Delay, To Achieve Constant Gain And Phase Margins For All Values Of Delay, Aidan O'Dwyer
Pi And Pid Controller Tuning Rule Design For Processes With Delay, To Achieve Constant Gain And Phase Margins For All Values Of Delay, Aidan O'Dwyer
Conference papers
This paper will discuss the design of PI and PID controller tuning rules to compensate processes with delay, that are modelled in a number of ways. The rules allow the achievement of constant gain and phase margins as the delay varies.
Dead-Time Compensators: Performance And Robustness Issues, James Syder, Thomas Heeg, Aidan O'Dwyer
Dead-Time Compensators: Performance And Robustness Issues, James Syder, Thomas Heeg, Aidan O'Dwyer
Conference papers
This paper will compare a number of PID and predictive controller strategies to compensate processes modelled in first order lag plus time delay (FOLPD) form. The performance and robustness of the resulting compensated systems are evaluated analytically (where appropriate) and in simulation.
Pid Compensation Of Time Delayed Processes: A Survey, Aidan O'Dwyer
Pid Compensation Of Time Delayed Processes: A Survey, Aidan O'Dwyer
Conference papers
An extensive literature exists on the PID compensation of time delayed processes. It is possible to identify themes that are common to many of the available techniques. The intention of the paper is to provide a framework against which the literature may be viewed.
Convergence Of Parameter And Delay Estimates Using Open Loop Time Domain Gradient Methods, Aidan O'Dwyer, John Ringwood
Convergence Of Parameter And Delay Estimates Using Open Loop Time Domain Gradient Methods, Aidan O'Dwyer, John Ringwood
Conference papers
This paper discusses the estimation of the parameters of a single input, single output (SISO) process, modelled in first order lag plus delay (FOLPD) form, using gradient methods in the open loop time domain. The paper considers the convergence of the process parameters to the model parameters. The convergence of the model delay is discussed first, when the non-delay model and process parameters are identical. The convergence of all of the model parameters is then considered, when all of the process parameters are unknown.
Time Delayed Process Model Parameter Estimation: A Classification Of Techniques, Aidan O'Dwyer
Time Delayed Process Model Parameter Estimation: A Classification Of Techniques, Aidan O'Dwyer
Conference papers
An extensive though scattered literature exists on the estimation of the model parameters of time delayed processes. However, it is possible to identify themes that are common to many of the proposed techniques. The intention of this paper is to provide a framework against which the literature may be viewed.
A Summary Of Pi And Pid Controller Tuning Rules For Processes With Time Delay. Part 1: Pi Controller Tuning Rules, Aidan O'Dwyer
A Summary Of Pi And Pid Controller Tuning Rules For Processes With Time Delay. Part 1: Pi Controller Tuning Rules, Aidan O'Dwyer
Conference papers
The ability of proportional integral (PI) and proportional integral derivative (PID) controllers to compensate many practical industrial processes has led to their wide acceptance in industrial applications. The requirement to choose either two or three controller parameters is perhaps most easily done using tuning rules. A summary of tuning rules for the PI control of single input, single output (SISO) processes with time delay is provided in this paper.
A Summary Of Pi And Pid Controller Tuning Rules For Processes With Time Delay. Part 2: Pid Controller Tuning Rules, Aidan O'Dwyer
A Summary Of Pi And Pid Controller Tuning Rules For Processes With Time Delay. Part 2: Pid Controller Tuning Rules, Aidan O'Dwyer
Conference papers
The ability of proportional integral (PI) and proportional integral derivative (PID) controllers to compensate many practical industrial processes has led to their wide acceptance in industrial applications. The requirement to choose either two or three controller parameters is perhaps most easily done using tuning rules. A summary of tuning rules for the PID control of single input, single output (SISO) processes with time delay is provided in this paper.
A Classification Of Techniques For The Compensation Of Time Delayed Processes. Part 1: Parameter Optimised Controllers, Aidan O'Dwyer, John Ringwood
A Classification Of Techniques For The Compensation Of Time Delayed Processes. Part 1: Parameter Optimised Controllers, Aidan O'Dwyer, John Ringwood
Conference papers
An extensive literature exists on the compensation of time delayed processes. It is possible to identify themes that are common to many of the available techniques. The intention of the two parts of this paper is to provide a framework against which the literature may be viewed; Part 1 of the paper considers the use of parameter optimised controllers for the compensation problem, with Part 2 of the paper considering the use of structurally optimised compensators. Conclusions are drawn at the end of Part 2.
Estimation Of The Parameters Of A Delayed Process Using Open Loop Time Domain Techniques, Morena Stolfa, Aidan O'Dwyer
Estimation Of The Parameters Of A Delayed Process Using Open Loop Time Domain Techniques, Morena Stolfa, Aidan O'Dwyer
Conference papers
In this paper, we present three different approaches to fit the experimental data of a process with time delay in the time domain. Two of the proposed methods are based on the step response, and the third is based on the pulse response. The effectiveness of these techniques is verified by simulation results and by real-time experimental data. Only first order lag plus time delay models are considered in this paper.
Robust Controller Design For Time Delay Systems Using H-Infinity Techniques, Susan Carr, Aidan O'Dwyer
Robust Controller Design For Time Delay Systems Using H-Infinity Techniques, Susan Carr, Aidan O'Dwyer
Conference papers
Using H-infinity control, the design problem is formulated in terms of user defined weighting polynomials on the process closed-loop sensitivity functions to achieve desired closed-loop performance and robust stability in the presence of process modelling error. In this paper stability conditions , in terms of the process sensitivity functions, are derived for processes containing a pure time delay for the following three design scenarios i) the time delay is neglected in the control design and is considered as part of the unmodelled process dynamics ii) A Pade approximation of the delay is included in the controller design and the effect …
Pi And Pid Controller Tuning Rules For Time Delay Processes: A Summary. Part 2: Pid Controller Tuning Rules, Aidan O'Dwyer
Pi And Pid Controller Tuning Rules For Time Delay Processes: A Summary. Part 2: Pid Controller Tuning Rules, Aidan O'Dwyer
Conference papers
A summary of tuning rules for the PID control of single input, single output (SISO) processes with time delay, modeled in stable first order lag plus time delay (FOLPD) form, is provided in this part of the paper.
A Classification Of Techniques For The Compensation Of Time Delayed Processes. Part 2: Structurally Optimised Controllers, Aidan O'Dwyer, John Ringwood
A Classification Of Techniques For The Compensation Of Time Delayed Processes. Part 2: Structurally Optimised Controllers, Aidan O'Dwyer, John Ringwood
Conference papers
Following on from Part 1, Part 2 of the paper considers the use of structurally optimised controllers to compensate time delayed processes.
Compensation Of Processes With Time Delays, Thomas Heeg, Aidan O'Dwyer
Compensation Of Processes With Time Delays, Thomas Heeg, Aidan O'Dwyer
Conference papers
Methods which allow comparisons in the use of PI and PID controller strategies for the control of first order lag plus time delay processes (FOLPD) are worthy of investigation because of the relative lack of work done in this area. In this paper, strategies for comparing performance and robustness for a PI or PID controlled FOLPD process are analysed and designed. The use of different PID controller structures for processes with time delay is also worth considering in detail. Various PID controller structures are compared by means of servo and regulator time responses, Bode plots and Nyquist plots.
The Identification And Control Of Processes With Time Delay, Susan Carr, Aidan O'Dwyer
The Identification And Control Of Processes With Time Delay, Susan Carr, Aidan O'Dwyer
Conference papers
The identification of the frequency response and process model parameters of systems with time delay using frequency domain techniques is evaluated in this paper. The performance of both Fourier Transform and Power Spectral Density techniques is considered. The benefits of employing modern model based design and delay compensation techniques, based on the identified process data, are assessed.
Performance And Robustness Issues In The Compensation Of Folpd Processes With Pi And Pid Controllers, Aidan O'Dwyer
Performance And Robustness Issues In The Compensation Of Folpd Processes With Pi And Pid Controllers, Aidan O'Dwyer
Conference papers
This paper will discuss the compensation of first order lag plus time delay (FOLPD) processes using PI and PID controllers whose parameters are specified using appropriate tuning rules. The gain margin, phase margin and maximum sensitivity of the compensated system as the ratio of time delay to time constant of the process varies, are used as ways of judging the performance and robustness of the system.
The Gain Scheduled Piece-Wise Adaptive Digital Control Of A Ph Process, Eugene O'Shaughnessy, Aidan O'Dwyer
The Gain Scheduled Piece-Wise Adaptive Digital Control Of A Ph Process, Eugene O'Shaughnessy, Aidan O'Dwyer
Conference papers
The compensation of a pH process is complicated by the non-linear nature of the process titration curve and the significant time delays that typically exist in such processes. This paper will propose the use of a gain scheduled piecewise adaptive PI controller to compensate the process. A pilot plant is controlled, with the control algorithm implemented on a programmable controller. SCADA software displays and trends the plant and controller signals.
Closed Loop Time Domain Gradient Methods For Parameter And Time Delay Estimation, M, Behan, M Cahill, M. Carry, G Clausen, V. Dooley, N. English, W. Grainger, D. O'Connor, Aidan O'Dwyer, John Ringwood
Closed Loop Time Domain Gradient Methods For Parameter And Time Delay Estimation, M, Behan, M Cahill, M. Carry, G Clausen, V. Dooley, N. English, W. Grainger, D. O'Connor, Aidan O'Dwyer, John Ringwood
Conference papers
This paper discusses the estimation of process parameters and time delay, in a Smith predictor structure, using gradient algorithms in the time domain. A number of estimation algorithms are outlined and applied in simulation to the estimation of the parameters of an appropriate process model. An analytical exploration of the technique is also provided.
The Control Of A Process With Time Delay By Using A Modified Smith Predictor Compensator, Aidan O'Dwyer, John Ringwood
The Control Of A Process With Time Delay By Using A Modified Smith Predictor Compensator, Aidan O'Dwyer, John Ringwood
Conference papers
A modification is proposed to the Smith predictor compensator structure for the control of a process with time delay. The modification facilitates the achievement of an improved closed loop system regulator response, with little degradation in the corresponding servo response. The compensator design procedure is discussed, and simulation results are provided to demonstrate the applicability of the method.
Model Parameter And Time Delay Estimation In The Frequency Domain, Aidan O'Dwyer, John Ringwood
Model Parameter And Time Delay Estimation In The Frequency Domain, Aidan O'Dwyer, John Ringwood
Conference papers
This paper discusses the estimation of the parameters (including the time delay) of single input, single output (SISO) process models from an appropriate number of arbitrarily specified points on the process frequency response. The method involves combining an analytical approach with a least squares approach using a gradient algorithm, to provide accurate and robust estimates of the parameters.