Design of low sensitivity controllers: Frequency domain technique

Design of low sensitivity controllers: Preregulator approach

“…Since the trajectory sensitivity can not be modelled accurately in a closed-loop formulation, the linear preregulator design techniques are investigated to approximate the sensitivity information. Two methods leading to transfer-function matrix form are developed, and the four design methods, designated as Methods I and II in (9) and Methods A and B in this paper, as well as the simple system (without sensitivity constraint) are compared. Figure 1 obviously shows the effect of these methods.…”

“…Figures 5 and 6 show the correctness of these results. Table 1 shows that Method B gives the least sensitive results, that the second is Method II (9), that the third is Method I (9), that the fourth is Method A, and that the simple system is the most sensitive one. Since there are some advantages in Methods II (9) and B as discussed above, the approach suggested in method B is recommended.…”

“…In this method, we will not encounter the trouble arised in (9). We will minimize the trajectory sensitivity and the total cost.…”

“…In order to overcome this difficulty, an estimation scheme that the part of variations of control due to parameter changes in the sensitivity vector can be approached as a constant under the low sensitivity design was proposed (9). In this paper, a preregulator scheme is proposed, i. e., the information of du/da t is initially approximated by treating the system without sensitivity constraints and is then applied to the sensitivity constrainted problem.…”

“…2-3. Deviations of step response at weighting matrix S, = l, and variable parameter a=0.Method II in(9) …”