% frequency response experiment % plant input: T_M % plant output: omega_M % format of datafile % 1st column ... frequency (Hz) % 2nd column ... gain from T_M to omega_M % 3rd column ... phase from T_M to omega_M % 4th column ... gain from T_M to omega_L % 5th column ... phase from T_M to omega_L frdata = load('ex1204_2.dat'); f = frdata(:,1); % frequency w = 2*pi*f; % angular frequency P_jw = frdata(:,2) .*exp(1i*pi/180.0*frdata(:,3)); P_g = frd(P_jw, w); J_M = 1.7E-05; % assumed to fit experimental result f_r = 58.9; % from experiment f_a = 15.8; % from experiment K_S = (2*pi)^2*J_M*(f_r^2 - f_a^2); J_L = K_S / (2*pi*f_a)^2; C_S = 2.0E-04; % assumed to fit experimental result C_L = 0.5e-3; % assumed to fit experimental result J = J_M + J_L; P_a = [0, 1, -1; -K_S/J_M, -C_S/J_M, C_S/J_M; K_S/J_L, C_S/J_L, -(C_S+C_L)/J_L]; P_b = [0; 1/J_M; 0]; P_c = [0, 1, 0]; P_d = 0; P0 = ss(P_a, P_b, P_c, P_d); P0_g = frd(P0, w); bode(P_g, '.b', P0_g, 'r');