Abstract: A method is described for acquiring data for relay-based controller tuning of a controller controlling a system. The method includes determining, based on controller output constraint, a relay amplitude representing an amplitude of a relay signal to be added to steady state controller output to obtain a sum signal to be fed to the system as system input during the acquiring data for relay-based controller tuning; and starting acquiring controller output data and system output data when detecting a steady state of system output while controller output is fed to the system as system input.

Abstract: A method is described for acquiring data for relay-based controller tuning of a controller controlling a system. The method includes determining, based on controller output constraint, a relay amplitude representing an amplitude of a relay signal to be added to steady state controller output to obtain a sum signal to be fed to the system as system input during the acquiring data for relay-based controller tuning; and starting acquiring controller output data and system output data when detecting a steady state of system output while controller output is fed to the system as system input.

Abstract: A method for detecting a steady-state in a process plant, the method includes: receiving a process value of the process plant, determining a recursive mean of the process value, calculating an arithmetic mean of the process value within a pre-determined window, determining a standard deviation of the process value within the pre-determined window and based on the calculated arithmetic mean, determining an upper limit and a lower limit of the process value based on the recursive mean of the process value and on the determined standard deviation, determining whether the calculated arithmetic mean is between the determined upper limit and the determined lower limit, and if the calculated arithmetic mean is between the determined upper limit and the determined lower limit, generating a first index indicating that the calculated arithmetic mean is between the determined upper limit and the determined lower limit.

Abstract: A performance measure of a second controller adapted to control a system is determined. First system input data and first system output data are obtained, while a first controller receives the first system output data and supplies first controller output to the system as the first system input data. A system delay is estimated between the first system input data and the first system output data using a Hilbert transform relations method. Second system output data is obtained, while the second controller receives a difference between second system output data and reference data and supplies second controller output to the system as second system input data. A minimum system output variance is estimated based on the estimated system delay and an impulse response of the system. The performance measure is estimated based on the estimated minimum system output variance and a variance of the second system output data.