Control of the IPDT plants: Part I: Internal feedback as a difference

There exists a plethora of publications about the controller design and synthesis. Only a few attempts to reduce the number of existing methods appeared. We tried to find a similarity and uniformity between them. We divided the controller design methods into the two different groups. Their classifying is based on the method used for the calculation of the internal (stabilizing) feedback. It can be either in a form of a difference or in the form of a ratio. This paper covers the first group of methods where the internal feedback is created as a difference. We will show that several such methods of controller synthesis are in fact identical and we also accompany the theory with a few examples.