Self-tuning controller

Claim 2

Process control apparatus for attaining a control system that has a selected closed-loop autonomous behavior, said control apparatus having signal monitoring means for monitoring a response signal being representative of the closed-loop autonomous behavior of the control system, controller means for generating a process control signal to affect a process so that a measured variable signal is directed toward a preselected value, said controller means including means for storing one or more control parameters, and means for generating said control signal as a function of said one or more control parameters and of said response signal, and adapter means for automatically adjusting at least one of said control parameters within said controller means, said control apparatus having the improvement in which said adapter means comprises measurement means for measuring at least two pattern features of said response signal, and for generating as a function of said pattern features a signal being representative of a complex root of the closed-loop autonomous behavior of the control system, and means for automatically modifying at least one of said control parameters as a function of said complex root signal, to adjust the closed-loop autonomous behavior of the control system.

Claim 3

Process control apparatus according to claim 1 wherein said measurement means further comprises selection means for selecting portions of said response signal, said selection means including means for measuring amplitude values of said response signal, means for storing one or more signal characteristics that are defined as functions of signal amplitude values and are determinative of one or more preselected signal patterns, and, means for determining said one or more signal characteristics of said response signal to select a series of amplitude values, wherein said series of amplitude values has said two pattern features and is representative of one of said preselected signal patterns.

Claim 4

Process control apparatus according to claim 2 wherein said selection means has means for storing signal characteristics representative of signal overshoot, of signal decay and of the half-period of a signal.

Claim 5

Process control apparatus according to claim 2, wherein said means for storing signal characteristics has means for storing signal characteristics representative of signal attenuation determinative of a damped signal.

Claim 6

Process control apparatus according to claim 2 wherein said means for determining signal characteristics includes means for selecting a series of amplitude values substantially representative of a damped sinusoid.

Claim 7

Process control apparatus according to claim 1 wherein said measurement means includes means for measuring amplitude values representative of the local extrema of said response signal, and means for measuring time intervals representative of the period of said response signal.

Claim 8

Apparatus according to claim 1 wherein said controller means further includes initiation means for selecting an initial set of said one or more control parameters for being modified by said adapter means, said initiation means having storage means for storing one or more sets of said control parameters, and selection means for selecting one of said stored sets of control parameters as a function of the magnitude of said response signal relative to a preselected threshold magnitude.

Claim 9

Apparatus according to claim 7 wherein said selection means further includes means for selecting said set of control parameters as a function of the magnitude of said response signal relative to the preselected threshold magnitude and as a function of a user-selected variable.

Claim 10

Process control apparatus for attaining a selected closed-loop autonomous behavior of a control system, said control apparatus having signal monitoring means for monitoring a response signal being representative of said closed-loop autonomous behavior of the control system, controller means for generating a process control signal to affect a process so that a measured variable signal is directed toward a preselected value, said controller means including means for storing one or more control parameters, and means for generating said control signal as a function of said one or more control parameters and of said response signal, and adapter means for automatically adjusting at least one of said control parameters within said controller means, said control apparatus having the improvement in which said adapter means comprises measurement means for measuring amplitude values of said response signal to characterize a first pattern feature representative of the attenuation of said response signal, and to characterize a second pattern feature representative of the time period of said response signal, said attenuation and said period of said response signal being substantially representative of a complex root of the closed-loop system, and, tuning means for automatically modifying at least one of said control parameters and including means for identifying a process model having one or more parameters that are a function of said attenuation and said time period, and further including means for selecting one or more controller parameters that have a known relation to said process model and said preselected closed-loop autonomous behavior of the control system.

Claim 11

Process control apparatus for attaining a selected closed-loop autonomous behavior of a control system, said control apparatus having signal monitoring means for monitoring a response signal being representative of said closed-loop autonomous behavior of the control system, controller means for generating a process control signal to affect a process so that a measured variable signal is directed toward a preselected value, said controller means including means for storing one or more control parameters, and means for generating said control signal as a function of said one or more control parameters and of said response signal, and adapter means for automatically adjusting at least one of said control parameters within said controller means, said control apparatus having the improvement in which said adapter means comprises measurement means for measuring amplitude values of said response signal to characterize a first pattern feature representative of the attenuation of said response signal, and to characterize a second pattern feature representative of the time period of said response signal, said attenuation and said period of said response signal being substantially representative of a complex root of the closed-loop system, and, tuning means for automatically modifying at least one of said control parameters and including means for identifying a process model having one or more parameters that are a function of said attenuation and said time period, and further including means for selecting one or more controller parameters that have a known relation to said process model and said preselected closed-loop autonomous behavior of the control system.

Claim 12

Process control apparatus according to claim 9, wherein said measurement means has means for storing four successive amplitude values, and means for determining said attenuation and said period of said response signal as a function of said stored amplitude values.

Claim 13

Process control apparatus according to claim 9 wherein said measurement means has means for storing three successive amplitude values, and means for determining said attenuation and said period of said response signal as a function of said stored amplitude values.

Claim 14

Process control apparatus according to claim 9 wherein said measurement means has means for storing two successive amplitude values and has means for determining said attenuation and said period of said response signal as a function of said amplitude values.

Claim 15

Process control apparatus according to claim 9 wherein said tuning means further comprises means for identifying a process model including means for storing at least two model processes wherein each of said model processes has two or more variable parameters, means for selecting, according to a predetermined criterion, one of said stored model processes for determining, according to a function of said measured attenuation and said period, said model parameters, and, means for selecting as a function of said model parameters and of said preselected criteria, a process model representative of the process connected within the control system.

Claim 16

Process control apparatus according to claim 13, wherein said measurement means further comprises means for sampling said response signal at a known interval and for generating a digital representation of said response signal.

Claim 17

Process control apparatus according to claim 14, wherein said tuning means further comprises means for selecting said process model being representative of said process connected within the control system as a function of said model parameters, said measured period and said digital sampling interval.

Claim 18

Process control apparatus according to claim 9 wherein said means for identifying a process model includes means for selecting between a gain-delay model or an integral-delay model.

Claim 19

Process control apparatus according to claim 9 wherein said tuning means further includes means for storing a table of predetermined controller parameters indexed relative to said selected process model.

Claim 20

Process control apparatus according to claim 9, wherein said tuning means has means for storing a process type variable and means for determining said one or more model parameters as a function of said process type variable, of said attenuation and of said period.

Claim 21

Control apparatus for generating a process model of a process connected within a closed-loop control system, said control apparatus comprising controller means for generating a process control signal to affect the operation of the process, said controller means including storage means for storing one or more control parameters, signal means for generating said process control signal as a function of said one or more control parameters, and signal monitoring means, coupled to the process, for measuring amplitude values and time values of a response signal representative of the closed-loop autonomous behavior of the control system and representative of an oscillatory signal behavior, root identification means for computing as a function of said amplitude and time values a signal substantially representative of the attenuation of said response signal and a signal substantially representative of the period of said response signal, and for generating as a function of said attenuation and said period, a signal substantially representative of a complex root of said closed-loop system, and process identification means, for generating as a function of said complex root signal and said control parameters, a model of said process.

Claim 22

Control apparatus for generating a process model of a process connected within a closed-loop control system, said control apparatus comprising controller means for generating a process control signal to affect the operation of the process, said controller means including storage means for storing one or more control parameters, signal means for generating said process control signal as a function of said one or more control parameters, and signal monitoring means, coupled to the process, for measuring amplitude values and time values of a response signal representative of the closed-loop autonomous behavior of the control system and representative of an oscillatory signal behavior, root identification means for computing as a function of said amplitude and time values a signal substantially representative of the attenuation of said response signal and a signal substantially representative of the period of said response signal, and for generating as a function of said attenuation and said period, a signal substantially representative of a complex root of said closed-loop system, and process identification means, for generating as a function of said complex root signal and said control parameters, a model of said process.

Claim 23

Apparatus according to claim 19 wherein said process identification means includes means for generating, as a function of said complex root signal and said control parameters, a gain signal substantially representative of a gain of said controller means, and a phase signal substantially representative of a phase angle of said controller means.

Claim 24

Apparatus according to claim 19 wherein said process identification means includes means for generating, as a function of said complex root signal and said control parameters, a gain signal substantially representative of a gain of the process, and a phase signal substantially representative of a phase angle of the process.

Claim 25

Apparatus according to claim 21 wherein said process identification means includes means for storing a process model having one or more variable parameters, and means for selecting values for said one or more variable parameters as a function of said phase signal and said gain signal.