This app allows straightforward design of PID-Type controllers based on the results from a relay tuning experiment and Ziegler-Nichols tuning rules.

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When put under closed loop control with a relay, i.e., an on/off controller, a process is put into sustained oscillations. From the amplitude of input and output the ultimate process gain can be computed. The period of oscillation is the ultimate process period. These two parameters are traditionally obtained from open loop experiments which can be time consuming and unsafe because the process can become unstable. Using a relay controller these values can be obtained quickly and safely.

A convenient input form allows entry of experiment parameters and results. Quickly select controller type (P, PI, PID) and mode (slow, normal, fast) to determine tuning parameters.

Keywords: PID, Control, Tuning, Ziegler Nichols, Relay, Åström, Hägglund