How to observe changing responses over time in simulink

Hello, i am trying to observe the change of position of a system with respect to time. The mass of the system changes at t=20s by 15%, and I can show this in Matlab, but my plot is coming from a simulink model including a PID controller and a Transfer Function. I have also been able to vary the transfer function with respect to time, which, I think should change the response of the system with respect to time, so my question is, how do I observe this change of the response with respect to time from Simulink.

clc
clear
%% Define knowns

g = 9.81; % gravity [m/s^2]
k = 1.32435*10^-4; % Magnet force constant, [N/amp]
x_0 = 0.015; % steady state position [m]
for t = 1:1:50
    if t <20
        m(t)=0.06;
     
    else
        m(t)=0.06+(0.06*0.15);
    end
end

i_0 = 1; % Steady state amps, assumed from NYU experiment [amp]

%% Define variable parameters
i = 1;
R = 10; % From NYU experiment [Ohm]
L = 0.4125; % Inductance from NYU experiment [Henry]

%% Checking Current System Stability
for t = 1:1:50
    if t < 20
        a(t) = (2*k*i_0)/(0.06*x_0^2); % num of TF
        b(t) = (2*k*i_0^2)/(0.06*x_0^3); % part of den for TF
    else
       a(t) = (2*k*i_0)/(0.069*x_0^2); % num of TF
       b(t) = (2*k*i_0^2)/(0.069*x_0^3); % part of den for TF
    end
end


        
% a(t) = (2*k*i_0)/(m(t)*x_0^2); % num of TF
% b(t) = (2*k*i_0^2)/(m(t)*x_0^3); % part of den for TF
% num = [a];
% den = [1 0 b];
% sys = tf(num,den)
% % step(sys,t)

%% Simulate Model
maglev_sim = sim('Maglev_Model.slx');

%% Plotting m = 0.06 kg response
figure(1)
plot(maglev_sim.maglev,'LineWidth',2)
title('Position Response for m = 0.06kg')
ylabel('Position (m)')
xlabel('Time (s)')

Answer 1

[Mathieu NOE]

in your simulink file, you are using the standard transfer function bloc that works only with fixed coefficients

you have to change that to time varying bloc , as example :

Model Gain-Scheduled Control Systems in Simulink - MATLAB & Simulink - MathWorks France