Self-tuning controller

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.

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.