Patent ID: 7937165

Claim:
A method for tuning a controller controlling a property of an industrial process having varying material flow rate, the method comprising: injecting excitation signals added to an output signal of the controller, receiving measurements of said property in response to said excitation signals, choosing a process model structure which is time continuous and comprises at least one parameter with unknown value, the parameter being independent of varying material flow rate, estimating a value of said at least one parameter, based on said measurements of said property and an output signal from the controller, calculating a model that describes dynamics from controller output to controller input based on the estimated value of said parameter, and on a basis thereof performing model based tuning of the controller, reducing a parameter update size, when an unrestricted update reaches outside an area of defined allowed parameter ranges, but making a parameter update in a same direction in a parameter space, and applying a same reduction factor to both regressors and prediction error, to be used in both parameter update and update of matrix holding information necessary in recursive estimation, thereby keeping parameter estimates within allowed ranges.