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AssigneeHitachi, Ltd.
InventorsYoshio Sato, Nobuo Kurihara, Masahide Nomura, Shigeyoshi Kawano, Tadayoshi Saito
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A system and method for the adaptive control of a process in which a feed forward control signal corresponding to a process demand is calculated according to a predetermined algebraic function, while a feedback correction signal is calculated on the basis of an error of a process feedback signal indicative of an error of a controlled variable from a predetermined setting, and the controlled variable of the process is controlled on the basis of the sum of these two signals. The adaptive control is such that, when a set point of the function deviates from the actual process demand, a value corresponding to the error appears in the feedback correction signal, and this value is used for automatically modifying the function itself to ensure the adaptive control of the process. A determination is made whether or not the process is in the steady state and when steady state operation is determined, the function of the feed forward control signal is modified.
A method for the adaptive control of a process comprising the steps of generating in accordance with a predetermined function a feed forward control signal for controlling a process variable on the basis of a process demand, generating an output representing a measured value of the process variable, generating an output representative of a predetermined value of the process variable, generating a feedback correction signal in accordance with a difference between the outputs of the measured and predetermined values of the process variable, controlling the process variable in accordance with the feed forward control signal and the feedback correcting signal, determining whether the process is in a steady state or not, and modifying the predetermined function utilized for generating the feed forward control signal when it is determined that the process is in the steady state, the modifying of the predetermined function utilized for generating the feed forward control signal being effected so as to reduce the amount of the feedback correction signal, and further comprising the step of modifying the feedback correction signal in accordance with the amount of modification of the predetermined function utilized in generating the feed forward control signal when the process is determined to be in the steady state.
An adaptive control system for controlling a process comprising function generator means for generating in accordance with a predetermined function a feed forward control signal for controlling a process variable on the basis of a process demand, means for generating an output representing a measured value of the process variable, means for generating an output representative of a predetermined value of the process variable, feedback correction signal means responsive to the outputs of the measured and predetermined values of the process variable for generating a feedback correction signal in accordance with a difference between the outputs, control means responsive to the feed forward control signal and feedback correcting signal for controlling the process variable in accordance therewith, judging means for determining whether the process is in a steady state or not, and modifying means responsive to the judging means determining that the process is in the steady state for modifying the predetermined function of the function generator means, the modifying means being responsive to the judging means determining that the process is in the steady state for modifying the predetermined function of the function generator means so as to reduce the amount of the feedback correction signal, and the modifying means being responsive to the judging means determining that the process is in the steady state for modifying the feedback correction signal means so as to modify the feedback correction signal in accordance with the amount of modification of the predetermined function of the function generator means.
Dependencies are inferred from the claim text.