Comments on “A Modification and the Tustin Approximation ” with a Concluding Proposition

It is noticed that the justification of the “modification of the Tustin approximation" proposed in [1] by means of the three examples is not convincing, because the choice of the examples is questionable and some calculations are not sufficiently accurate. It is shown that some good properties of the proposed modification can be justified by using the Tustin approximation of a continuous-time (CT) model for the discrete-time (DT) system. It is stressed that the proposed modification has only a limited value, since from application point of view the use of CT models is more reasonable. As the conclusion the DT controller design procedure by using CT methods is proposed.