PID Control
Researchers: Karl Johan Åström, Josefin Berner, Tore Hägglund, and Kristian Soltesz.
This project has been in progress since the beginning of the eighties and resulted in industrial products as well as several PhD theses. Three monographs on PID control that are based on experiences obtained in the project have also been published. The last is "Advanced PID Control", published in 2005. It is also translated to Spanish 2009: "Control PID avanzado". The research is currently focused on the following topics:
Automatic Tuning of PID Controllers
The PID controller is used almost everywhere in industry, but a lot of PID controllers work poorly due to bad tuning. To be able to automatically tune PID controllers is a useful feature that has been around since the beginning of the 80's. A lot has happened since then both regarding PID knowledge, but mainly in available computing power, and we are now developing new autotuners that can take advantage of that. More information about our current autotuner research is found on the page for Automatic Tuning.
Optimal Robust PID design
A Matlab-based software tool for optimal PID design has been developed at the department. The software finds the PI or PID controller that minimizes the Integrated Absolute Error (IAE) value during a step load disturbance on the process input, with respect to robustness constraints on the sensitivity and complementary sensitivity functions. This PID design method is called SoftWare-based Optimal Robust Design (SWORD).
Varying the time constant of the low-pass filter, it is possible to find optimal or near-optimal solutions to an optimization problem extended with a noise sensitivity constraint. As the time constant of the low-pass filter increases, the PID controller will gradually transform into a PI controller and then finally an I controller. This gives a natural set of I, PI and PID controllers to choose from. The final controller can be selected based on visual feedback of the control signal activity due to measurement noise.
Download the latest SWORD PID Design Tool version for Matlab
Download the previous PID Design Tool version for Matlab
PID design by convex optimization
Convex optimization has grown to become a mature and powerful tool in a vast number of research fields. Design of PID controllers subject to robustness constraint is not a convex optimization problem, however, it fits well into the framework of the convex-concave procedure. Using that procedure, tuning algorithms for both SISO and MIMO PID controllers have been developed. Although globally optimal controllers cannot be guaranteed, the method produces robust controllers with good performance. The work is done in collaboration with Stephen Boyd, Stanford University.
Optimization-Based Robust PID Design in Matlab
Compact and relatively efficient implementations of software for solving the PID design problems introduced above under Optimal Robust PID Design and PID design by convex optimization are available through the Matlab code PIDopt. The software also allows for co-design of PID controllers and measurement filters.
Download latest version of PIDopt for Matlab
Or clone directly from git@gitlab.control.lth.se:kristian/PIDopt.git.
Interactive learning modules for PID control
We are also developing interactive learning modules for PID control. The modules are designed to speed up learning and to enhance understanding of the behavior of loops with PID controllers. The modules are implemented in SysQuake, and the work is done in collaboration with professor Sebastián Dormido at UNED, Madrid, and José Luis Guzmán at Universidad de Almería.
The tools can be downloaded from Universidad de Almería.
Publications
J. L. Guzmán, T. Hägglund: "Tuning rules for feedforward control from measurable disturbances combined with PID control : a review". International Journal of Control, 97:1, pp. 2–15, 2024.
Francisco García-Mañas, Tore Hägglund, Josè Luis Guzman, Francisco Rodríguez, Manuel Berenguel: "Multivariable control of nighttime temperature and humidity in greenhouses combining heating and dehumidification". IFAC-PapersOnLine, 56:2, pp. 9900–9905, 2023.
Josè Luis Guzman, Tore Hägglund: "Selecting control schemes and tuning rules in feedforward control". IFAC-PapersOnLine, 56:2, pp. 3253–3258, 2023.
Tore Hägglund: Process Control in Practice. De Gruyter, 2023.
Tore Hägglund, Sumit Shinde, Alfred Theorin, Ulf Thomsen: "An industrial control loop decoupler for process control applications". Control Engineering Practice, 123:June, pp. –, 2022.
Jonas Hansson, Magnus Svensson, Alfred Theorin, Emma Tegling, Kristian Soltesz, Tore Hägglund, Karl Johan Åström: "Next generation relay autotuners—analysis and implementation". In IEEE Conference on Control Technologies and Applications, San Diego, United States, August 2021.
Magnus Lundh, Alfred Theorin, Tore Hägglund, Jonas Hansson, Magnus Svensson, Karl Johan Åström, Kristian Soltesz: "Model optimization for autotuners in industrial control systems". In 26th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA), Västerås, Sweden, September 2021.
T. Hägglund: "A feedforward approach to mid-ranging control". Control Engineering Practice, 108:March, pp. 1–10, 2021.
Antonio Visioli, Tore Hägglund: "Inversion-based feedforward actions in a ratio control system". In American Control Conference 2019, Philadelphia, United States, July 2019.
Tore Hägglund: Praktisk processreglering (4 uppl.). Studentlitteratur AB, 2019.
Tore Hägglund: "The one-third rule for PI controller tuning". Computers and Chemical Engineering, 127, pp. 25–30, 2019.
Ángeles Hoyo, José Carlos Moreno, José Luis Guzmán, Tore Hägglund: "Robust QFT-based PID controller for a feedforward control scheme". IFAC-PapersOnLine, pp. 262–267, 2018.
Tore Hägglund, José Luis Guzmán: "Development of basic process control structures". IFAC-PapersOnLine, 51:4, pp. 775–780, 2018.
Kristian Soltesz, Anton Cervin: "When is PID a good choice?". IFAC-PapersOnLine, 51:4, pp. 250–255, 2018.
Josefin Berner, Kristian Soltesz, Tore Hägglund, Karl Johan Åström: "An experimental comparison of PID autotuners". Control Engineering Practice, 73, pp. 124–133, 2018.
Max Veronesi, Josè Luis Guzman, Antonio Visioli, Tore Hägglund: "Closed-loop tuning rules for feedforward compensator gains". IFAC-PapersOnLine, 50:1, pp. 7523–7528, 2017.
Tore Hägglund: "The Tracking Ratio Station". Control Engineering Practice, 69, pp. 122–130, 2017.
Josefin Berner: Automatic Controller Tuning using Relay-based Model Identification. PhD Thesis Department of Automatic Control, Lund University, Sweden, October 2017.
Pedro Mercader, Kristian Soltesz, Alfonso Baños: "Robust PID Design by Chance-Constrained Optimization". Journal of the Franklin Institute, 354:18, pp. 8217–8231, 2017.
Josefin Berner, Kristian Soltesz: "Short and Robust Experiments in Relay Autotuners". In 22nd IEEE International Conference on Emerging Technologies and Factory Automation; ETFA2017, Limassol, Cyprus, September 2017.
Josefin Berner, Kristian Soltesz, Karl Johan Åström, Tore Hägglund: "Practical Evaluation of a Novel Multivariable Relay Autotuner with Short and Efficient Excitation". In IEEE Conference on Control Technology and Applications, CCTA 2017, Kohala Coast, United States, August 2017.
Josefin Berner, Kristian Soltesz, Tore Hägglund, Karl Johan Åström: "Autotuner identification of TITO systems using a single relay feedback experiment". IFAC-PapersOnLine, 50:1, pp. 6619–6623, 2017.
Kristian Soltesz, Pedro Mercader, Alfonso Baños: "An automatic tuner with short experiment and probabilistic plant parameterization". International Journal of Robust and Nonlinear Control, 27:11, pp. 1857–1873, 2017.
Kristian Soltesz, Chriss Grimholt, Sigurd Skogestad: "Simultaneous design of proportional–integral–derivative controller and measurement filter by optimisation". IET Control Theory and Applications, 11:3, pp. 341–348, 2016.
Pedro Mercader, Kristian Soltesz, Alfonso Baños: "Autotuning of an In-Line pH Control System". In 21st IEEE International Conference on Emerging Technologies and Factory Automation, ETFA 2016, Berlin, Germany, September 2016.
Josefin Berner, Tore Hägglund, Karl Johan Åström: "Asymmetric relay autotuning - Practical features for industrial use". Control Engineering Practice, 54, pp. 231–245, 2016.
Josefin Berner, Tore Hägglund, Karl Johan Åström: "Improved Relay Autotuning using Normalized Time Delay". In American Control Conference, 2016, Boston, United States, July 2016.
Alfred Theorin, Josefin Berner: "Implementation of an Asymmetric Relay Autotuner in a Sequential Control Language". In IEEE International Conference on Automation Science and Engineering (IEEE CASE 2015), August 2015.
Stephen Boyd, Martin Hast, Karl Johan Åström: "MIMO PID Tuning via Iterated LMI Restriction". International Journal of Robust and Nonlinear Control, 26:8, pp. 1718–1731, 2015.
Tore Hägglund: "Autotuning". In: Encyclopedia of Systems and Control, Springer, 2015.
Josefin Berner: "Automatic Tuning of PID Controllers Based on Asymmetric Relay Feedback". Licentiate Thesis Department of Automatic Control, Lund University, Sweden, April 2015.
Olof Garpinger: "Optimal PI and PID Parameters for a Batch of Benchmark Process Models Representative for the Process Industry". Technical Report Department of Automatic Control, Lund University, Sweden, April 2015.
Martin Hast, Tore Hägglund: "Optimal proportional–integral–derivative set-point weighting and tuning rules for proportional set-point weights". IET Control Theory and Applications, 9:15, pp. 2266–2272, 2015.
Alfred Theorin, Tore Hägglund: "Derivative backoff: The other saturation problem for PID controllers". Journal of Process Control, 33, pp. 155–160, 2015.
José Luis Guzmán, Tore Hägglund, Max Veronesi, Antonio Visioli: "Performance indices for feedforward control". Journal of Process Control, 26, pp. 26–34, 2015.
José Luis Guzmán, Tore Hägglund, Karl Johan Åström, Sebastián Dormido, Manolo Berenguel, Yves Piquet: "Understanding PID design through interactive tools". In 19th IFAC World Congress, 2014, Cape Town, South Africa, August 2014.
Vanessa Romero Segovia, Tore Hägglund, Karl Johan Åström: "Design of measurement noise filters for PID control". In 19th IFAC World Congress, 2014, Cape Town, South Africa, August 2014.
Josefin Berner, Karl Johan Åström, Tore Hägglund: "Towards a New Generation of Relay Autotuners". In 19th IFAC World Congress, 2014, Cape Town, South Africa, August 2014.
Olof Garpinger, Tore Hägglund, Karl Johan Åström: "Performance and robustness trade-offs in PID control". Journal of Process Control, 24:5, pp. 568–577, 2014.
Vanessa Romero Segovia, Tore Hägglund, Karl Johan Åström: "Measurement noise filtering for PID controllers". Journal of Process Control, 24:4, pp. 299–313, 2014.
Carlos Rodríguez, José Luis Guzmán, Manuel Berenguel, Tore Hägglund: "Optimal feedforward compensators for systems with right-half plane zeros". Journal of Process Control, 24:4, pp. 368–374, 2014.
Vanessa Romero Segovia, Tore Hägglund, Karl Johan Åström: "Measurement noise filtering for common PID tuning rules". Control Engineering Practice, 32, pp. 43–63, 2014.
C. Rodríguez, José Luis Guzmán, Manuel Berenguel, Tore Hägglund, J. E. Normey-Rico: "Diseño de controladores por Adelanto para Inversión de Retardo no realizable". In XXXIV Jornadas de Automática, Terrassa, Spain, September 2013.
Martin Hast, Karl Johan Åström, Bo Bernhardsson, Stephen P. Boyd: "PID Design by Convex-Concave Optimization". In European Control Conference, 2013, Zurich, Switzerland, July 2013.
C. Rodríguez, Josè Luis Guzman, Manuel Berenguel, Tore Hägglund: "Generalized feedforward tuning rules for non-realizable delay inversion". Journal of Process Control, 23:9, pp. 1241–1250, 2013.
Tore Hägglund: "A Unified Discussion on Signal Filtering in PID Control". Control Engineering Practice, 21:8, pp. 994–1006, 2013.
Martin Hast, Tore Hägglund: "Design of Optimal Low-Order Feedforward Controllers for Disturbance Rejection". In 17th Nordic Process Control Workshop, 2012, Kgs Lyngby, Denmark, January 2012.
Per-Ola Larsson, Tore Hägglund: "Comparison Between Robust PID and Predictive PI Controllers with Constrained Control Signal Noise Sensitivity". In IFAC Conference on Advances in PID Control, Brescia, Italy, March 2012.
Martin Hast, Tore Hägglund: "Design of Optimal Low-Order Feedforward Controllers". In IFAC Conference on Advances in PID Control, Brescia, Italy, March 2012.
Olof Garpinger, Tore Hägglund, Lars Cederqvist: "Software for PID design: benefits and pitfalls". In IFAC Conference on Advances in PID Control, Brescia, Italy, March 2012.
2018-02-05