Abstract
The main purpose of using feedback is to compensate for external disturbances and for model uncertainties. Actually, when a sufficiently accurate model of the integral process is available (and the process dynamics does not change significantly during the process operations), control performance can be improved in general by conveniently employing an additional feedforward (open-loop) control law, thus employing a two-degree-of-freedom control. After having presented the standard two-degree-of-freedom control scheme, this chapter focuses on different methodologies for the design and the implementation of a feedforward control law, to be adopted in conjunction with the feedback action provided by a PID controller. It is shown that the problem can be approached from different points of view. In particular, regarding the set-point following task, two kinds of approaches are presented: the design of a causal feedforward action and of a noncausal feedforward action. In the first case a (nonlinear) two-state control law is described. In the second case, to be employed when desired process output transitions are known in advance, strategies based on input–output inversion are explained both in the continuous-time and discrete-time frameworks.
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References
Åström, K.J., Wittenmark, B.: Computer-Controlled Systems—Theory and Design. Prentice Hall, Upper Saddle River (1997)
Åström, K.J., Hägglund, T., Hang, C.C., Ho, W.K.: Automatic tuning and adaptation for PID controllers—a survey. Control Eng. Pract. 1, 699–714 (1993)
Beschi, M., Piazzi, A., Visioli, A.: On the practical implementation of a noncausal feedforward technique for PID control. In: Proceedings European Control Conference, pp. 1806–1811, Budapest, HU, 2009
Devasia, S., Chen, D., Paden, B.: Nonlinear inversion-based output tracking. IEEE Trans. Autom. Control 41, 930–943 (1996)
Hägglund, T., Åström, K.J.: Supervision of adaptive control algorithms. Automatica 36(2), 1171–1180 (2000)
Hunt, L.R., Meyer, G.: Stable inversion for nonlinear systems. Automatica 33(8), 1549–1554 (1997)
Hunt, L.R., Meyer, G., Su, R.: Noncausal inverses for linear systems. IEEE Trans. Autom. Control 41, 608–611 (1996)
Kristiansson, B., Lennartson, B.: Robust and optimal tuning of PI and PID controllers. IEE Proc., Control Theory Appl. 149(1), 17–25 (2001)
Leva, A., Cox, C., Ruano, A.: Hands-on PID autotuning: a guide to better utilisation. Technical report, IFAC Technical Brief (2001), available at www.ifac-control.org
Lewis, F.L.: Optimal control. In: Levine, W.S. (ed.) The Control Handbook, pp. 759–778. CRC Press, Boca Raton (1996)
Morari, M., Zafiriou, E.: Robust Process Control. Prentice-Hall, Inc., Englewood Cliffs (1989)
Perez, H., Devasia, S.: Optimal output transitions for linear systems. Automatica 39, 181–192 (2003)
Piazzi, A., Visioli, A.: Minimum-time system-inversion-based motion planning for residual vibration reduction. IEEE/ASME Trans. Mechatron. 5(1), 12–22 (2000)
Piazzi, A., Visioli, A.: Optimal inversion-based control for the set-point regulation of nonminimum-phase uncertain scalar systems. IEEE Trans. Autom. Control 46, 1654–1659 (2001)
Piazzi, A., Visioli, A.: Optimal noncausal set-point regulation of scalar systems. Automatica 37(1), 121–127 (2001)
Piazzi, A., Visioli, A.: Robust set-point constrained regulation via dynamic inversion. Int. J. Robust Nonlinear Control 11, 1–22 (2001)
Piazzi, A., Visioli, A.: Using stable input-output inversion for minimum-time feedforward constrained regulation of scalar systems. Automatica 41(2), 305–313 (2005)
Piazzi, A., Visioli, A.: A noncausal approach for PID control. J. Process Control 16, 831–843 (2006)
Press, W.H., Teukolsky, S.A., Vetterling, W.T., Flannery, B.P.: Numerical Recipes: The Art of Scientific Computing. Cambridge University Press, Cambridge (1995)
Sung, S.W., Lee, I.-B., Lee, B.-K.: On-line process identification and automatic tuning method for PID controllers. Chem. Eng. Sci. 53, 1847–1859 (1998)
Veronesi, M., Visioli, A.: A technique for abrupt load disturbance detection in process control systems. In: Proceedings 17th IFAC World Congress on Automatic Control, pp. 14900–14905, Seoul, ROK, 2008
Visioli, A.: Optimal tuning of PID controllers for integral and unstable processes. IEE Proc., Control Theory Appl. 148(2), 180–184 (2001)
Visioli, A.: A new design for a PID plus feedforward controller. J. Process Control 14, 455–461 (2004)
Visioli, A., Piazzi, A.: Improving set-point following performance of industrial controllers with a fast dynamic inversion algorithm. Ind. Eng. Chem. Res. 42, 1357–1362 (2003)
Wallen, A.: Tools for autonomous process control. PhD thesis, Lund Institute of Technology, Lund (2000)
Wallen, A., Åström, K.J.: Pulse-step control. In: Proceedings 15th IFAC World Congress on Automatic Control, Barcelona, E, 2002
Zou, Q., Devasia, S.: Preview-based stable-inversion for output tracking of linear systems. ASME J. Dyn. Syst. Meas. Control 121, 625–630 (1999)
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Visioli, A., Zhong, QC. (2011). Feedforward Control. In: Control of Integral Processes with Dead Time. Advances in Industrial Control. Springer, London. https://doi.org/10.1007/978-0-85729-070-0_6
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DOI: https://doi.org/10.1007/978-0-85729-070-0_6
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