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US 4,250,543 AGranted
Method of controlling production processes and apparatus therefor
AssigneeScans Associates, Inc.
InventorsRichard L. Smith, Kent Van Allen
Life of this patent
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AssigneeScans Associates, Inc.
InventorsRichard L. Smith, Kent Van Allen
Estimating the term…
The specification discloses a novel method for controlling production processes of a pneumatic, electrical or hydraulic nature and apparatus therefor. The method, and therefore the apparatus for performing said method, counteracts any process change by utilizing the error difference and the rate of change of the error difference between a feedback signal related to a current condition of the process and a desired value related to the desired condition of the process. The error difference and rate of change and then utilized to produce a correction signal which is adapted to remain unchanged as long as the process being controlled, and the desired value signal, both remain in static condition, but which also has a unique look ahead feature such that said correction signal attempts to become saturated as soon as a new desired value is supplied, or a process change occurs. The correction signal, if saturated, is brought out of saturation much faster by using both the rate of change of the actual error difference between said desired value and said feedback signals and the actual error difference between said signals in a manner which is much faster than if only the error difference was used. If said correction signal never does reach a saturation point, or if it is saturated, upon becoming unsaturated, the correction signal is then changed much faster than previously possible by using the rate of change of the error difference, rather than the error difference only.
A method of controllinga process using a process controller including the steps of providing a desired value signal to said process controller related to the condition to which it is desired to set said process, providing a feedback signal to said process controller from the process being controlled indicating the current state of the process, producing a correction signal from said signals which will look ahead and attempt to become saturated as soon as a new desired value is supplied or a process change occurs by utilizing the rate of change of said signals and the error difference between said signals, which will remain unchanged as long as the process being controlled, and the desired value signal both remain unchanged and in a static condition, which will, if saturated, be brought out of saturation by utilizing said error difference and said rate of change in a manner to change said correction signal in value much faster than if said error difference only were used, and which will, if said process is in a dynamic condition, be changed in a series of occurrences to a value smaller in magnitude, but of either polarity, until it arrives at a value related to said condition it is desired to set said process to, and utilizing said correction signal to cause said process to arrive at said desired condition.
A process controller including means to accept a desired value signal related to a condition to which it is desired to set a process, means to accept a feedback signal related to the current state of the process, means to produce a correction signal from said signals which will look ahead and attempt to become saturated as soon as a new desired value is supplied or a process change occurs by utilizing the rate of change of said signals and the error difference between said signals, which will remain unchanged as long as the process being controlled, and the desired value signal both remain unchanged and in a static condition, which will, if saturated, be brought out of saturation by utilizing said error difference and said rate of change in a manner to change said correction signal in value much faster than if said error difference only were used, and which will, if said process is in a dynamic condition, be changed in a series of occurrences to a value smaller in magnitude, but of either polarity, until it arrives at a value related to said condition it is desired to set said process to, and utilizing said correction signal to cause said process to arrive at said desired condition.
Dependencies are inferred from the claim text.