www.gusucode.com > robust 案例源码程序 matlab代码 > robust/FeedbackAroundAnUncertainPlantExample.m
%% Feedback Around an Uncertain Plant % It is possible to form interconnections of |uss| objects. A common % example is to form the feedback interconnection of a given controller % with an uncertain plant. %% % First create the uncertain plant. Start with two uncertain real parameters. % Copyright 2015 The MathWorks, Inc. gamma = ureal('gamma',4); tau = ureal('tau',.5,'Percentage',30); %% % Next, create an unmodeled dynamics element, |delta|, and a first-order % weighting function, whose DC value is 0.2, high-frequency gain is 10, and % whose crossover frequency is 8 rad/sec. delta = ultidyn('delta',[1 1],'SampleStateDimension',5); W = makeweight(0.2,6,6); %% % Finally, create the uncertain plant consisting of the uncertain % parameters and the unmodeled dynamics. P = tf(gamma,[tau 1])*(1+W*delta); %% % You can create an integral controller based on nominal plant parameters. % Nominally the closed-loop system will have damping ratio of 0.707 and % time constant of |2*tau|. KI = 1/(2*tau.Nominal*gamma.Nominal); C = tf(KI,[1 0]); %% % Create the uncertain closed-loop system using the |feedback| command. CLP = feedback(P*C,1); %% % Plot samples of the open-loop and closed-loop step responses. As expected % the integral controller reduces the variability in the low frequency % response. subplot(2,1,1); stepplot(P,5) subplot(2,1,2); stepplot(CLP,5)