459085 Error-Triggered on-Line Model Identification for Model-Based Feedback Control
In this work, we propose a prediction error metric that can be used to trigger on-line model identification to update a linear empirical model for use in model-based control. A moving horizon error detector is developed based on the total relative error between the measured states and the states predicted using the current linear empirical model throughout the time period corresponding to the length of the moving horizon. Once a threshold value of the relative error metric is exceeded, model re-identification is triggered using the most recent input/output data, and the model-based controller is updated to include the new model. This prevents constant updating of the model and the controller, but allows for updates when the model no longer captures the nonlinear dynamics of the process. The method is demonstrated using Lyapunov-based economic model predictive control  and shown to improve the profit and to reduce plant-model mismatch compared to using one linear empirical model for the entire period of operation both for the case of plant variations (modeled through catalyst deactivation) and an expansion of the region of process operation.
 Alanqar A, Ellis M, Christofides PD. Economic model predictive control of nonlinear process systems using empirical models. AIChE Journal. 2015;61:816-830.
 Qin SJ, Badgwell TA. A survey of industrial model predictive control technology. Control Engineering Practice. 2003;11:733-764.
 Larimore WE. Canonical variate analysis in identification, filtering, and adaptive control. In: Proceedings of the 29th IEEE Conference on Decision and Control. Honolulu, HI, 1990;596-604.
 Verhaegen M, Dewilde P. Subspace model identification Part 1. The output-error state-space model identification class of algorithms. International Journal of Control. 1992;56:1187-1210.
 Heidarinejad M, Liu J, Christofides PD. Economic model predictive control of nonlinear process systems using Lyapunov techniques. AIChE Journal. 2012;58:855-870.