| 1. |
- Berner, Josefin, et al.
(författare)
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An experimental comparison of PID autotuners
- 2018
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Ingår i: Control Engineering Practice. - : Elsevier BV. - 0967-0661. ; 73, s. 124-133
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Tidskriftsartikel (refereegranskat)abstract
- In this paper two novel autotuners are compared with two industrially available ones. The aim is to see if the research frontline can improve the industry standard of today. Experiments are made on three laboratory processes with different characteristics. Two lag-dominated processes of which one is a level control problem with fast dynamics, and one a temperature control problem with slow dynamics, as well as one delay-dominated level control process. Both the experiments and the obtained controller performances are evaluated and discussed. The results show that the performance of the stateof-the-art industrial autotuners can be significantly improved.
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| 2. |
- Berner, Josefin, et al.
(författare)
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Asymmetric relay autotuning - Practical features for industrial use
- 2016
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Ingår i: Control Engineering Practice. - : Elsevier BV. - 0967-0661. ; 54, s. 231-245
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Tidskriftsartikel (refereegranskat)abstract
- The relay autotuner provides a simple way of finding PID controller parameters. Even though relay autotuning is much investigated in the literature, the practical aspects are not that well-documented. In this paper an asymmetric relay autotuner with features such as a startup procedure and adaptive relay amplitudes is proposed. Parameter choices and handling of noise, disturbances, start in non-steady state and other possible error sources are discussed. The autotuner is implemented and tested in an industrial air handling unit to show its use in practice. The experiments show good results, and prove that the proposed simple autotuner is well-suited for industrial use. But the experiments also enlighten possible error sources and remaining problems.
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| 3. |
- Berner, Josefin, et al.
(författare)
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Autotuner identification of TITO systems using a single relay feedback experiment
- 2017
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Ingår i: IFAC-PapersOnLine. - : Elsevier BV. - 2405-8963. ; 50:1, s. 6619-6623
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Tidskriftsartikel (refereegranskat)abstract
- Relay autotuning has proven very successful for single-input single-output systems. This paper proposes an identification method for relay autotuning of systems with two inputs and two outputs (TITO systems). The combination of asymmetric relay feedback and output error identification admits short tuning time, without the need for limit cycle convergence. The method is successfully demonstrated on relevant system models, including the Wood-Berry distillation column.
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| 4. |
- Berner, Josefin, et al.
(författare)
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Improved Relay Autotuning using Normalized Time Delay
- 2016
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Ingår i: American Control Conference (ACC), 2016.
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Konferensbidrag (refereegranskat)abstract
- The relay autotuner provides a simple way offinding PID controllers of sufficient performance. By usingan asymmetric relay function the excitation of the process isimproved. This gives better models, and hence a better tuning,without increasing the time consumption or complexity of theexperiment. Some processes demand more accurate modelingand tuning to obtain controllers of sufficient performance.These processes can be singled out by their normalized timedelays and be subject to further modeling efforts. The autotunerproposed in this paper provides a simple way of findingthe normalized time delay from the experiment, and uses itfor model and controller selection. The autotuner has beenimplemented and evaluated both in a simulation environmentand by industrial experiments.
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| 5. |
- Berner, Josefin, et al.
(författare)
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Practical Evaluation of a Novel Multivariable Relay Autotuner with Short and Efficient Excitation
- 2017
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Ingår i: IEEE Conference on Control Technology and Applications, CCTA 2017. ; , s. 1505-1510
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Konferensbidrag (refereegranskat)abstract
- In this paper we propose an autotuning method that combines a setup for decentralized relay autotuning of two-input two-output systems with an identification method that uses short experiments to estimate up to second-ordertime-delayed systems. A small modification of the experiment gives better low-frequency excitation and improved models. The method is successfully demonstrated in simulations and on a quadruple tank process.
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| 6. |
- Berner, Josefin, et al.
(författare)
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Towards a New Generation of Relay Autotuners
- 2014
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Ingår i: 19th IFAC World Congress, 2014.
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Konferensbidrag (refereegranskat)abstract
- The relay autotuner for PID control is based on the simple idea of investigating process dynamics by the oscillation obtained when the PID controller is replaced by a relay unction. In this paper an asymmetric relay function is used, which provides an equation for the static gain of the process. A method to find the normalized time delay is proposed and the benefits of this is discussed. Ways to find low-order models from the experiment are described. Considerations of how to choose the relay parameters are made and some examples are given.
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| 7. |
- Garpinger, Olof, et al.
(författare)
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Criteria and Trade-offs in PID Design
- 2012
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Ingår i: 2nd IFAC Conference on Advances in PID Control 2012. - 9783902823182 ; , s. 47-52
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Konferensbidrag (refereegranskat)abstract
- Control design is a rich problem which requires that many issues such as load disturbances and set-point responses, model uncertainty, and measurement noise are taken into account. These issues are discussed for design of PI and PID controllers. The purpose is to give insight into the different criteria and their trade-offs, not to give specific tuning methods.
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| 8. |
- Garpinger, Olof, et al.
(författare)
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Performance and robustness trade-offs in PID control
- 2014
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Ingår i: Journal of Process Control. - : Elsevier BV. - 1873-2771 .- 0959-1524. ; 24:5, s. 568-577
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Tidskriftsartikel (refereegranskat)abstract
- Control design is a rich problem which requires consideration of many issues such as load disturbance attenuation, set-point tracking, robustness with respect to process variations and model uncertainty, and effects of measurement noise. The purpose of this paper is to provide insight into the trade-offs between performance and robustness explicitly. This is accomplished by introducing plots that show the trade-offs for PI and PID control. These also provide valuable understanding of design compromises used for common PI design methods.
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| 9. |
- Guzmán, José Luis, et al.
(författare)
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Feedforward Control Concepts through Interactive Tools
- 2011
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Ingår i: 18th IFAC World Congress, 2011.
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Konferensbidrag (refereegranskat)abstract
- This paper presents an interactive software tool for basic and advanced concepts of feedforward control. The ideal compensator is analyzed to show how the effects of the load disturbances are eliminated from the process output. Furthermore, it is also shown that the ideal compensator is seldom realizable, since the compensator may be non-causal, it may be unstable, it may have infinite high-frequency gain because of derivative action, and it may require a more complicated structure than what is available. The drawback of not taking the feedback controller into account during the typical open-loop feedforward design is also studied. The proposed software tool helps to evaluate all these situations in an interactive way, enabling users to find possible design solutions to these problems.
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| 10. |
- Guzmán, José Luis, et al.
(författare)
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Interactive Learning Module: Basic Modelling and Identification Concepts
- 2008
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Ingår i: 17th IFAC World Congress, 2008.
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Konferensbidrag (refereegranskat)abstract
- This paper describes an interactive tool focused on teaching and learning basic concepts about modelling and identification. Modelling and identification play fundamental roles in the field of automatic control, since it is not possible to perform a control system design without having a model describing the dynamics of the process to be controlled. The tool presented in this work is dedicated to describe the most important aspects of basic modelling centralized on first and second order systems with dead-time and zero effects.
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