Diagnostic for poorly tuned control loops
AssigneePulp and Paper Research Institute of Canada
InventorsLahoucine Ettaleb, Alain André Roche
Life of this patent
Estimating the term…
Abstract
A method and apparatus to perform an automatic diagnosis for the poor performance of a control loop, and to determine whether or not the malfunctioning is caused principally by a poor adjustment of the controller tuning parameters. The method makes use of the fact that a poorly tuned control loop amplifies disturbances in a narrow frequency range around the so-called resonant frequency. The method comprises measuring an error in a control loop over time to determine a power spectral density of the error, determining a best fit analytical function describing the power spectral density and measuring a diagnostic value from a difference between the best fit analytical function and the power spectral density of the error.
Claims13
A control loop diagnostic method comprising:
- measuring an error in a control loop over time to determine a power spectral density of said error;
- determining a best fit analytical function describing said power spectral density;
- measuring a diagnostic value from a difference between said best fit analytical function and said power spectral density of said error;
- and
- outputting said diagnostic value,
- wherein said diagnostic value provides a classification indication of one of tuning error and malfunction of said control loop.
A computer readable memory comprising a plurality of instructions which when executed perform the steps of:
- measuring an error in a control loop over time to determine a power spectral density of said error;
- determining a best fit analytical function describing said power spectral density;
- measuring a diagnostic value from a difference between said best fit analytical function and said power spectral density of said error;
- and
- outputting said diagnostic values,
- wherein said diagnostic value provides a classification indication of one of tuning error and malfunction of said control loop.
Dependencies are inferred from the claim text.