使用 System Identification Toolbox 估计含噪频率响应模型
打开 Simulink® 模型,并指定要线性化的模型部分:
load_system('magball'); io(1) = linio('magball/Desired Height',1); io(2) = linio('magball/Magnetic Ball Plant',1,'output');
计算稳态工作点,并线性化模型:
op = findop('magball',operspec('magball'),... findopOptions('DisplayReport','off')); sys = linearize('magball',io,op);
创建一个啁啾信号,并使用它来估计频率响应:
in = frest.Chirp('FreqRange',[1 1000],... 'Ts',0.001,... 'NumSamples',1e4); [~,simout] = frestimate('magball',io,op,in);
使用 System Identification Toolbox™ 软件估计一个五阶状态空间模型。比较解析线性化和状态空间模型的结果:
input = generateTimeseries(in); output = simout{1}.Data; data = iddata(output,input.Data(:),in.Ts); sys_id = n4sid(detrend(data),5,'cov','none'); bodemag(sys,ss(sys_id('measured')),'r') legend('Linear model obtained using LINEARIZE',... 'State-space model using System Identification Toolbox',... 'Location','SouthWest')