In this demo, we demonstrate our control selection and tuning procedure (in part) on a canal with just one reach. 

Our procedure consists of two steps: (1) determination of canal dynamic properties (delay time, surface area and Bode parameters), and (2) tuning, based on these parameters. 

In the first step, the canal dynamic parameters are derived from the physical parameters of the reach. They vary with flow rate, and therefore, they are identified for both minimal and maximal flow (to provide extreme values). Normally, we use a hydrodynamic model to identify these, but for this demo we estimate them from formulas as given in the theoretical back ground, references [1] and [2]. Interestingly, our formulas are usually rather close to the values obtained from the hydrodynamic model, and therefore, we use these to initiate identification. 

In the second step, a PI controller is tuned using formulas as described in [1] and [2]. These formulas provide a phase margin of at least 45 degrees, and a loop gain of 0.5 maximally. The result is a closed loop system that is tuned tightly, i.e. increasing the gain with a factor of about 2 leads to instability. Depending on the reach's properties, performance may or may not be good. If the perfomance is unsatifactory our tuning procedure involves a next step, where the controller's constants are optimized using multiple model optimisation. This step is not included in this demo.

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