Feedback control method and system having variable deadband
First Claim
1. A feedback automatic control apparatus for performing feedback control such that a control amount with which an object being controlled may correspond with a target value, comprising:
- first dead zone setting means for setting a first dead zone including said target value and having a first width,second dead zone setting means for setting a second, non-zero dead zone including said target value and having a width narrower than that of said first dead zone and being entirely within the first dead band,means for measuring time elapsed from a start of control toward the target value, andcontrol means for controlling said object being controlled such that the control amount of said object being controlled falls within the range of said first dead zone as derived from said first dead zone setting means at the start of control and for controlling said object being controlled such that said control amount of said object being controlled falls within the range of the second dead zone as derived from said second dead zone setting means after the lapse of a predetermined time period after said start of control measured by said elapsed time measuring means, said control means comprising means responsive to (a) said target value, (b) the first dead zone as derived from said first dead zone setting means and (c) a current control amount for gradually decreasing as a function of time the width of said first dead zone set in said first dead zone setting means to the width of said second dead zone set in said second dead zone setting means.
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Abstract
An automatic feedback controller for maintaining water level in a dam initially compares target and sensed water levels to derive a deviation value. Simultaneously, a first dead zone having a relatively wide width contiguous to the target level is set. The first set dead zone is compared with the deviation value to open and close a dam gate such that the deviation value becomes smaller than the first dead zone width. When a predetermined time has elapsed, a second dead zone having a width narrower than that of the first dead zone is set. The second dead zone is then compared with the deviation value to open or close the gate such that the deviation value becomes smaller than the second dead zone width.
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Citations
20 Claims
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1. A feedback automatic control apparatus for performing feedback control such that a control amount with which an object being controlled may correspond with a target value, comprising:
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first dead zone setting means for setting a first dead zone including said target value and having a first width, second dead zone setting means for setting a second, non-zero dead zone including said target value and having a width narrower than that of said first dead zone and being entirely within the first dead band, means for measuring time elapsed from a start of control toward the target value, and control means for controlling said object being controlled such that the control amount of said object being controlled falls within the range of said first dead zone as derived from said first dead zone setting means at the start of control and for controlling said object being controlled such that said control amount of said object being controlled falls within the range of the second dead zone as derived from said second dead zone setting means after the lapse of a predetermined time period after said start of control measured by said elapsed time measuring means, said control means comprising means responsive to (a) said target value, (b) the first dead zone as derived from said first dead zone setting means and (c) a current control amount for gradually decreasing as a function of time the width of said first dead zone set in said first dead zone setting means to the width of said second dead zone set in said second dead zone setting means. - View Dependent Claims (2)
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3. A feedback control method for controlling a variable parameter to obtain a target value, comprising the steps of:
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presetting a first dead zone having a first width and including the target value of said parameter; measuring elapsed time following a start of control toward the target value; controlling, with the first dead zone, the parameter to approach said target value so the parameter is within the first dead zone; and after a predetermined time period after said start of control, controlling, with a second, non-zero dead zone having a width wholly within and narrower than that of the first dead zone and including said target value, the parameter to approach said target value so the parameter is within the second dead zone, said second dead zone being obtained by gradually decreasing as a function of time the width of said first dead zone after said predetermined time period.
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4. A feedback control apparatus for energizing an actuator so a variable controlled by the actuator approaches a set point value comprising means responsive to a signal having a magnitude indicative of a monitored value of the variable and the set point value for deriving an error signal having a magnitude indicative of the deviation of the set point and monitored values, means responsive to the error signal for controlling the actuator to cause the variable to approach the set point value, said controlling means including:
- means for establishing a series of N successive time dependent dead band values for the error signal, where N is an integer greater than 1, the dead band values decreasing only monotonically as the successive time dead band values are derived during a particular series, the actuator being energized only while the error signal magnitude is greater than each of the successive time dependent dead band values.
- View Dependent Claims (5, 6, 7, 8)
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9. A feedback control method for energizing an actuator so a variable controlled by the actuator approaches a set point value comprising monitoring the value of the variable, responding to the monitored value of the variable and the set point value to derive an error signal having a magnitude indicative of the deviation of the set point and monitored values, in response to the error signal controlling the actuator to cause the variable to approach the set point value, said controlling step including:
- establishing a series of N successive time dependent dead band values for the error signal, where N is an integer greater than 1, the dead band values decreasing only monotonically as the successive time dependent dead band values are derived during a particular series, the actuator being energized only while the error signal magnitude is greater than each of the successive time dependent dead band values.
- View Dependent Claims (10, 11, 12, 13)
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14. A method of controlling a parameter with an actuator comprising the steps of:
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(a) establishing a target value for the parameter, (b) monitoring the value of the parameter, (c) setting an initial dead band zone including the set point value for the actuator at the time the target value is established, (d) gradually reducing in only a monotonic manner the width of the dead band zone for the established target value from the intial dead band zone as control time for the parameter increases, whereby the dead band zone has a time dependent gradually decreasing monotonic variable value, (e) comparing the monitored and target values for the parameters to derive an indication of an error between them, (f) comparing the indicated error between the monitored and target values with the time dependent gradually decreasing monotonic variable value for the dead band zone, and (g) in response to comparing step (f) controlling said actuator so the parameter is varied toward the target value only when the error indication of step (e) is greater than the time dependent decreasing monotonic variable value for the dead band. - View Dependent Claims (15, 16, 17)
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18. Apparatus for controlling a parameter with an actuator in response to an indication of a value of the parameter comprising:
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(a) means for establishing a target value for the parameter, (b) means for setting an initial dead band zone including the set point value for the actuator at the time the target value is established, (c) means for gradually reducing in only a monotonic manner the width of the dead band zone for the established target value from the initial dead band zone as control time for the parameter increases, whereby the dead band zone has a time dependent gradually decreasing monotonic variable value, (d) means for comparing the monitored and target values for the parameters to derive an indication of an error between them, (e) means for comparing the indicated error between the monitored and target values with the time dependent gradually decreasing monotonic variable value for the dead band zone, and (f) means responsive to comparing means (e) for controlling said actuator so the parameter is varied toward the target value only when the error indication derived by comparing means (d) is greater than the time dependent gradually decreasing monotonic variable for the dead band. - View Dependent Claims (19, 20)
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Specification