Coefficient Diagram Method (CDM) is the one of the most effective control design methods in literature. It gives control systems that are very stable and robust, system responses without overshoot and very small settling time. The CDM, resolve the classical control problem after selecting a few meaningful design parameters and by automatically determining a target characteristic polynomial for the closedloop system. The classical CDM design was originally only performed in s-domain. But since, all industrial controllers are digital controllers, it is necessary to improve a digital controller based on CDM. In this paper, the Digitalized Coefficient Diagram method is introduced (D-CDM) and this new digital controller design method applied to different control systems. The very satisfactory results obtained by the new design method are discussed in details.

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The coefficient diagram method (CDM) is one of the most effective control design methods. It creates control systems that are very stable and robust with responses without the overshoot and small settling time. Furthermore, all control parameters of the control systems are changed by varying some adjustment parameters in CDM depending on the demands. The model reference adaptive systems (MRAS) are the systems that follow and change the control parameters according to a given model reference system. There are several methods to combine the CDM with MRAS. One of these is to use the MRAS parameters as a gain of the CDM parameters. Another is to directly use the CDM parameters as the MRAS parameters. In the industrial applications, the system parameters can be changed frequently, but if the controller, by self-tuning, recalculates and develops its own parameters continuously, the system becomes more robust. Also, if the poles of the controlled systems approach the jw axis, the response of the closed-loop MRAS becomes more and more insufficient. In order to obtain better results, CDM is combined with a self-tuning model reference adaptive system. Systems controlled by a model reference adaptive controller give responses with small or without overshoot, have small settling times, and are more robust. Thus, in this paper, a hybrid combination of MRAS and CDM is developed and two different control structures of the control signal are investigated. The two methods are compared with MRAS and applied to real-time process control systems.