Abstract: A predictive and self-tuning PI controller includes an apparatus for variably assigning gains thereto in accordance with specified time functions following a change in set-point. The control gains are computed in accordance with a plurality of input parameters and subsequently continuously adjusted to set-point errors based on a GPC approach thereby to optimize performance indices derived from simple and classical user specifications. Variation and tuning of control gains in accordance with set-point errors permits the PI controller to be useful in the general area of process control and applicable to a wider range of processes compared to traditional PI control, including time-delay processes, unstable processes and processes with time-varying dynamics.

Abstract: This invention provides a novel process identification and control package for high performance. For process identification, a simple yet effective and robust identification method is presented using process step responses to give a continuous transfer function with time-delay without iteration. A new relay, called cascade relay, is devised to get more accurate and reliable points on the process frequency response. For controller tuning, the internal model principle is employed to design single-loop controller PID or high-order types with best achievable control performance. The process identification and control design parts can be easily integrated into control system auto-tuning package. Further, a general control scheme for disturbance rejection is given which can significantly improve disturbance rejection performance over conventional feedback systems with time delays. Practical issues such as noises, real-time implementation and tuning guidelines are also provided.

Abstract: Briefly, a preferred embodiment of the present invention includes an apparatus for tuning a regulator in a process controller. The digitized output from a standard relay and a parasitic relay are fed through digital to analog converter providing signals at 0.5&ohgr;c, &ohgr;c and 1.5&ohgr;c to the process, where &ohgr;c is the process critical frequency. The apparatus records the digitized relay output u′ and the digitized process output y′ until stationary oscillations are reached. The outputs u′ and y′ are then used to calculate the process frequency response at 0.50&ohgr;c, &ohgr;c and 1.5&ohgr;c. This data is then used to design the regulator, the output of which is converted to analog form and inputted to control the process.

Abstract: A simple yet effective and robust identification method is presented using process step responses for process identification that can provide a continuous transfer function with time-delay without iteration. A cascade relay provides accurate and reliable more points on the process frequency response. The internal model principle is employed to design single-loop controller of PID or high-order types with best achievable control performance for controller tuning, e.g. both single and multivariable cases are covered. The process identification and control design portions can be easily integrated into a control system auto-tuning package. Further, a general control scheme for disturbance rejection is given which can significantly improve disturbance rejection performance over conventional feedback systems with time delays. Practical issues such as noises, real-time implementation and tuning guidelines are also provided.

Abstract: A frequency domain auto-tuning and continually adapting control regulating apparatus is applied to a linear stable process. A FFT based identification is applied to non-transformable samples of transient signals to obtain simultaneous and accurate multiple-point estimates of a frequency domain approximation of the process transfer function as an estimate of a frequency response. A linear least squares multiple-point-fitting process provides regulator design parameters. A multiple-point-fitting transfer function modeling process is disclosed, and an adaptive regulator design process is applied to compensate for changes in the process set-point or for load disturbances. In addition, techniques are provided for auto-tuning of multivariable regulators.