Automatic control has become one of the standard engineering fields and is inherently part of electrical engineering. Industrial controllers in any form are only a part of the hardware necessary for the control of industrial processes in, e.g., the process industry or manufacturing. The design of an industrial control system is greatly facilitated by an auto-tuning system, if it is available as part of the controller. Since the majority of control hardware for industry is of the proportional-integral-derivative (PID) type, most of the patents relating to auto-tuning are also about this type of control, though other patented methods and systems for control are available. In this paper, a survey of patents for autotuning methods and systems for industrial control is given. The patents are grouped into methods and systems based on model-based tuning with non-parametric and parametric models, relay tuning, multiple controllers for nonlinear processes, and other approaches. More stress is put on recent patents, but a wider survey of auto-tuning patents published in the past two decades is also given in the paper. The methods being patented are becoming more sophisticated and more universal and consequently they provide better assistance to the work of control-design engineers.
Keywords: Auto-tuning system, industrial controllers, process control, PID control, controller tuning
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