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Method and apparatus for model-based control of an open-loop process

  • US 5,010,473 A
  • Filed: 08/31/1989
  • Issued: 04/23/1991
  • Est. Priority Date: 08/31/1989
  • Status: Expired due to Term
First Claim
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1. A method for controlling a process to obtain a specified output, Os, where the process is described by a linear model that defines an output of the process as a function of a specified control signal, wherein the control signal controls an actuator that affects the process, said method comprising the steps of:

  • (a) arbitrarily selecting a first value, X1, and a second value, X2, for the control signal, and initializing a plurality of state variables in the model;

    (b) as a function of the first and second values of the control signal, which are respectively input to the model, determining corresponding first and second output values, O1 and O2, that would be obtained at the end of an interval of time, Δ

    t, were the control signal to be applied for this interval;

    (c) interpolating with respect to the first and second values of the control signal and corresponding first and second output values to determine a desired value, Xd, for the control signal that should produce the specified output, Os, at the end of the time interval, Δ

    t;

    (d) for the time interval, Δ

    t, operating the process using the desired value, Xd, determined in step (c) for the control signal;

    (e) determining a value, Xa, of the control signal actually used by the actuator during the time interval, Δ

    t;

    (f) using the model, determining a computed value for the output, Oc, as a function of the value of the control signal determined in step (e); and

    (g) reiteratively repeating steps (b) through (f), each successive iteration using values for the state variables in the model that depend on the computed value of the output determined in step (f) of the previous iteration, so that control of the process tracks changes in the specified output and the process quickly converges on the specified output.

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