Tore Hägglund

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This paper presents an analysis of the Ziegler-Nichols frequency response method for tuning PI controllers, showing that this method has severe limitations. The limitations can be overcome by a simple modification for processes where the time delay is not too short. By a major modification it is possible to obtain new tuning rules that also cover processes(More)
This paper presents a fast, interactive and easily modifiable software tool for robust PID design. The Matlab based program is supposed to give people with moderate knowledge on PID control a possibility to learn more and also be a future part of an autotuner. The PID design is made by minimizing the integrated absolute error value during a load disturbance(More)
Large control signal derivatives or inter-sample differences may harm actuators. An optimization constraint limiting such variations, related to measurement noise, is derived. Using the constraint, optimal PI, PID and measurement filters with different orders are designed for several processes and compared to the optimal linear controller of high order(More)