System and method for controlling processes
First Claim
1. A controller to control the operation of a system, said system having at least one controllable input and at least one measurable variable, said system including a first signal conditioner to convert a control signal from said controller to an input form required by said system for said controllable input and, a second signal conditioner to detect and convert said measurable variable to a data signal having a format compatible with said controller, said controller comprising:
- a processor having two input terminals and an output terminal, one of said input terminals disposed to be coupled to said second signal conditioner of said system to receive said data signal, the second of said input terminals disposed to receive a signal representative of a user selected set point for the operation of said system, and said output terminal disposed to be coupled to said first signal conditioner to provide said control signal for conversion to said at least one controllable input of said system, said processor to control the operation of said controller and to sequentially calculate and develop said control signal to control the operation of said system; and
a memory coupled to said processor and said second signal conditioner to store previous data signals, and intermediate results and values from said processor;
wherein said processor sequentially approximates a present error as the difference between a present set point and a present value of said measurable variable, and calculates a present slope in error of said system;
wherein said processor sequentially sets a present control signal from said controller proportional to a sum of a previous control signal, the present error, and the present slope in error.
1 Assignment
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Accused Products
Abstract
A multi-purpose controller for analog variables of one dimension which closely controls such variables to set point by making sequential corrections to the level of input to the system of the variable based on: system response time, relationship of controller output to the variable, deviation of the variable from set point, and change in system load as determined by combining change in error with change in system input. The controller has a self tuning capability and can provide generation of the set point according to a set of variable parameters. It can be configured as a stand alone controller, as an intelligent Input/Output device for another intelligent device, or be resident in another intelligent device such as a programmable controller, computer or other microprocessor based device.
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Citations
51 Claims
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1. A controller to control the operation of a system, said system having at least one controllable input and at least one measurable variable, said system including a first signal conditioner to convert a control signal from said controller to an input form required by said system for said controllable input and, a second signal conditioner to detect and convert said measurable variable to a data signal having a format compatible with said controller, said controller comprising:
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a processor having two input terminals and an output terminal, one of said input terminals disposed to be coupled to said second signal conditioner of said system to receive said data signal, the second of said input terminals disposed to receive a signal representative of a user selected set point for the operation of said system, and said output terminal disposed to be coupled to said first signal conditioner to provide said control signal for conversion to said at least one controllable input of said system, said processor to control the operation of said controller and to sequentially calculate and develop said control signal to control the operation of said system; and a memory coupled to said processor and said second signal conditioner to store previous data signals, and intermediate results and values from said processor; wherein said processor sequentially approximates a present error as the difference between a present set point and a present value of said measurable variable, and calculates a present slope in error of said system; wherein said processor sequentially sets a present control signal from said controller proportional to a sum of a previous control signal, the present error, and the present slope in error. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A controller to control the operation of a system, said system having at least one controllable input and at least one measurable variable, said system including a first signal conditioner to convert a control signal from said controller to an input form required by said system for said controllable input and, a second signal conditioner to detect and convert said measurable variable to a data signal having a format compatible with said controller, said controller comprising:
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a processor having two input terminals and an output terminal, one of said input terminals disposed to be coupled to said second signal conditioner of said system to receive said data signal, the second of said input terminals disposed to receive a signal representative of a user selected set point for the operation of said system, and said output terminal disposed to be coupled to said first signal conditioner to provide said control signal for conversion to said at least one controllable input of said system, said processor to control the operation of said controller and to sequentially calculate and develop said control signal to control the operation of said system; a memory coupled to said processor and said second signal conditioner to store previous data signals, and intermediate results and values from said processor; and a time generator coupled to said processor to generate a base cycle time of said processor; wherein said processor approximates a system response time for said system as the total time of the difference in time between when a difference in said control signal is applied to a first coupling unit and when a difference is noted in said data signal representative of a change in measurable variable by said controller; wherein said processor determines a system characteristic that is proportional to the ratio of a change in said control signal to a resultant change in said measurable variable;
a present error between actual measurable variable and the set point for the measurable variable; and
a present slope in error of said measurable variable;wherein a cycle time of said processor is the time necessary to make measurements and perform calculations; and wherein said processor sequentially sets a present control signal proportional to the sum of a previous control signal, said present error multiplied by said system characteristic and said cycle time divided by said system response time, and a present change in load that is arrived at by doubling said present slope in error multiplied by said system characteristic.
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17. A controller to control the operation of a system, said system having at least one controllable input and at least one measurable variable, said system including a first signal conditioner to convert a control signal from said controller to an input form required by said system for said controllable input and, a second signal conditioner to detect and convert said measurable variable to a data signal having a format compatible with said controller, said controller comprising:
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a processor having two input terminals and an output terminal, one of said input terminals disposed to be coupled to said second signal conditioner of said system to receive said data signal, the second of said input terminals disposed to receive a signal representative of a user selected set point for the operation of said system, and said output terminal disposed to be coupled to said first signal conditioner to provide said control signal for conversion to said at least one controllable input of said system, said processor to control the operation of said controller and to sequentially calculate and develop said control signal to control the operation of said system; a memory coupled to said processor and said second signal conditioner to store previous data signals, and intermediate results and values from said processor; and a time generator coupled to said processor to generate a base cycle time of said processor; wherein said controller controls the rate at which the operation of said system is changed over a period of time to achieve operation at a selected set point by making adjustments to a present set point at selected intervals, initially several parameter and variable values are preset or initialized and stored in said memory including final set point, previous set point, previous rate of change of set point, maximum rate of change of set point and acceleration of set point, and the value of said output of said second signal conditioner corresponding to said measurable value is stored in said memory; and wherein said processor during each cycle time compares said present set point with said final set point to determine if a change in said present set point is necessary, if said previous set point equals said final set point, said present rate of change of set point and acceleration of set point are each set to zero, resulting in said set point remaining unchanged and the present set point being set equal said previous set point, and if said previous set point is less than or greater than said final set point, the values of said present rate of change of set point and acceleration of set point may be adjusted to cause said present set point to change to achieve said final set point. - View Dependent Claims (18, 19, 20, 21)
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22. A method for controlling the operation of a system by developing a control signal, said system having at least one controllable input and at least one measurable variable, said system including a first signal conditioner to convert said control signal from a controller to an input form required by said system for said controllable input and, a second signal conditioner to detect and convert said measurable variable to a data signal having a format compatible with said controller, said controller disposed to receive a signal representative of a user selected set point for the operation of said system, said method of developing said control signal comprising the steps of:
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a. sequentially approximating a present error as the difference between a present set point and a present value of said measurable variable; and
calculate a present slope in error of said system;b. sequentially setting said present control signal proportional to a sum of a previous control signal, the present error, and the present slope in error; and c. approximating a response time for said system as the total time of the difference in time between when a difference in said control signal is applied to said first coupling unit and when a difference is noted in said data signal that is representative of a chance in said measurable variable. - View Dependent Claims (23, 24, 25, 26, 27)
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28. A method for controlling the operation of a system by developing a control signal, said system having at least one controllable input and at least one measurable variable, said system including a first signal conditioner to convert said control signal from a controller to an input form required by said system for said controllable input and, a second signal conditioner to detect and convert said measurable variable to a data signal having a format compatible with said controller, said controller disposed to receive a signal representative of a user selected set point for the operation of said system, wherein cycle time is the time necessary to make measurements and perform calculations, said method of developing said control signal comprising the steps of:
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a. generating a base cycle time; b. approximating a system response time for said system as the total time of the difference in time between when a difference in said control signal is applied to said first coupling unit and when a difference is noted in said data signal that is representative of a change in said measurable variable; c. sequentially approximating a present error as the difference between a present set point and a present value of said measurable variable; d. calculating a present slope in error of said system; e. approximating a system characteristic that is proportional to a change in said control signal to a resultant change in said data signal that is representative of a change in said measurable variable; f. approximating a present change in load by doubling said present slope in error multiplied by said system characteristic; and g. sequentially setting a present control signal proportional to the sum of a previous control signal, said present error multiplied by said system characteristic and said cycle time divided by said system response time, and said present change in load.
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29. A method for controlling the operation of a system by developing a control signal, said system having at least one controllable input and at least one measurable variable, said system including a first signal conditioner to convert said control signal from a controller to an input form required by said system for said controllable input and, a second signal conditioner to detect and convert said measurable variable to a data signal having a format compatible with said controller, said controller disposed to receive a signal representative of a user selected set point for the operation of said system, said method of developing said control signal comprising the steps of:
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a. generating a base cycle time; b. presetting or initializing final set point, previous set point, previous rate of change of set point, maximum rate of change of set point and acceleration of set point, and the value of said data signal corresponding to said measurable value; c. comparing, during each cycle time, a present set point with said final set point to determine if a change in said present set point is necessary; d. if as a result of step c. said previous set point equals said final set point, said present rate of change of set point and acceleration of set point are each set to zero, resulting in said set point remaining unchanged and the present set point being set equal said previous set point; and e. if as a result of step d. said previous set point is less than or greater than said final set point, the values of said present rate of change of set point and acceleration of set point may be adjusted to cause said present set point to change to achieve said final set point. - View Dependent Claims (30, 31, 32, 33)
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34. A computer-implemented method for controlling the operation of a system by developing a control value, said system having at least one controllable input and at least one measurable variable, said computer-implemented method comprising the steps of:
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a. entering a user selected set point for the operation of said system; b. sequentially approximating a present error as the difference between a present set point and a present value of said measurable variable; and
calculating a present slope in error of said system;c. sequentially setting a present control value proportional to a sum of a previous control signal, the present error, and the present slope in error; and d. approximating a response time for said system as the total time of the difference in time between when a difference in said control value is applied to said system and when a difference is noted in said measurable variable. - View Dependent Claims (35, 36, 37, 38, 39)
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40. A computer-implemented method for controlling the operation of a system by developing a control value, said system having at least one controllable input and at least one measurable variable, wherein cycle time is the time necessary to make measurements and preform calculations, said method of developing said control value comprising the steps of:
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a. entering a user selected set point for the operation of said system; b. generating a base cycle time; c. approximating a system response time for said system as the total time of the difference in time between when a difference in said control value is applied to said controllable input of said system and when a difference is noted in said measurable variable; d. sequentially approximating a present error as the difference between a present set point and a present value of said measurable variable; e. calculating a present slope in error of said system; f. approximating a system characteristic that is proportional to a change in said control signal to a resultant change in said data signal that is representative of a change in said measurable variable; g. approximating a present change in load by doubling said present slope in error multiplied by said system characteristic; and h. sequentially setting a present control value proportional to the sum of a previous control value, said present error multiplied by said system characteristic and said cycle time divided by said system response time, and said present change in load.
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41. A computer-implemented method for controlling the operation of a system by developing a control value, said system having at least one controllable input and at least one measurable variable, said method of developing said control value comprising the steps of:
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a. entering a user selected set point for the operation of said system; b. generating a base cycle time; c. presetting or initializing final set point, previous set point;
previous rate of change of set point, maximum rate of change of set point and acceleration of set point, and said measurable value;d. comparing, during each cycle time, a present set point with said final set point to determine if a change in said present set point is necessary; e. if as a result of step d. said previous set point equals said final set point, said present rate of change of set point and acceleration of set point are each set to zero, resulting in said set point remaining unchanged and the present set point being set equal said previous set point; and f. if as a result of step e. said previous set point is less than or greater than said final set point, the values of said present rate of change of set point and acceleration of set point may be adjusted to cause said present set point to change to achieve said final set point. - View Dependent Claims (42, 43, 44, 45)
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46. A method for controlling the operation of a system by developing a control signal, said system having at least one controllable input and at least one measurable variable, said system including a first signal conditioner to convert said control signal from a controller to an input form required by said system for said controllable input and, a second signal conditioner to detect and convert said measurable variable to a data signal having a format compatible with said controller, said controller disposed to receive a signal representative of a user selected set point for the operation of said system, said method of developing said control signal comprising the steps of:
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a. sequentially approximating a present error as the difference between a present set point and a present value of said measurable variable; and
calculating a present slope in error of said system;b. sequentially setting said present control signal proportional to a sum of a previous control signal, the present error, and the present slope in error; and c. approximating a system characteristic that is proportional to a change in said control signal to a resultant change in said data signal that is representative of a change in said measurable variable. - View Dependent Claims (47, 48)
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49. A computer-implemented method for controlling the operation of a system by developing a control value, said system having at least one controllable input and at least one measurable variable, said computer-implemented method comprising the steps of:
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a. entering a user selected set point for the operation of said system; b. sequentially approximating a present error as the difference between a present set point and a present value of said measurable variable; and
calculating a present slope in error of said system;c. sequentially setting said present control value proportional to a sum of a previous control signal, the present error, and the present slope in error; and d. approximating a system characteristic that is proportional to a change in-said control value to a resultant change in said measurable variable. - View Dependent Claims (50, 51)
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Specification