Generate repeated sequence block uisng matlab code

Hello, please I want to generate repeated sequence plot using MATLAB codes but not simulink. I have written the code and the interpolation. However, I think my 'for loop' to pick all the points in the sequence is not capturing all. I have given the scripts below and I have attached one of the similar plots I have genrated using SIMULINK's repeating sequence block.

   dt=1e-4;
    T = 200;
    n0=1;
    time=0:dt:T;
    nt=length(time);
    ref=zeros(nt,1);



    %time_point=[0	100	700	1000	1300	1600	1780	2080	2260	2560	2680	2980	3040	3340	3400	3700]
    %pow_point=[1	1	0.9	0.9	0.8	0.8	0.65	0.65	0.95	0.95	0.55	0.55	0.15	0.15	0.95	0.95]

    %time_point=[0 20 30 50 60 80 90 110 130 150];%work with only this time
    %time_point=[0 10 40 70 80 100 110 130 140 150];
    %time_point=[0 30 40 50 60 70 90 100 140 150];
    time_point=[0 20 30 50 60 80 90 110 130 200];
    %pow_point=[0.8 0.8 0.4 0.4 0.8 0.8 0.4 0.4 0.8 0.8];power Transient
    %pow_point=[1 1 0.4 0.4 1 1 0.4 0.4 1 1];
    %pow_point=[1 1 0.4 0.4 0.6 0.6 0.8 0.8 1 1];
    %pow_point=[0.9 0.9 0.3 0.3 0.9 0.9 0.3 0.3 0.9 0.9];
    pow_point=[0.7 0.7 0.4 0.4 0.4 0.4 0.6 0.6 0.7 0.7];
    %pow_point=[0.5 0.5 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1];

ref_old=pow_point(1);
for it=1:nt %to vectorize nt or make each point of nt
    if(it>1)
        time(it)=time(it-1)+dt;%to be able to make equal time step of the time
        ref_old=ref(it-1); %for each time slot 
    end
    ref(it)=ref_old;
    i1=1;
    i2=1;
    for ii=1:length(time_point)-1
        if(time_point(ii)<=time(it) && time(it)<=time_point(ii+1))
            i1=ii;
            i2=ii+1;
            frac1=(time_point(ii+1)-time(it))/(time_point(ii+1)-time_point(ii));
            frac2=1.0-frac1;
            ref(it)=frac1*pow_point(i1)+frac2*pow_point(i2);
            break
        end
    end

end
ref(:)=ref(:);
yref=(ref.*n0);
for s =1:nt
    setpoint=yref(s);
end

Answer 1

[Yash]

Hi Kamal,

There are a few issues and improvements in your code to generate repeated sequence block's functionality:

• The line "time(it)=time(it-1)+dt;" inside the loop is unnecessary because you've already defined your "time" array using "time=0:dt:T;".
• The line "ref_old=pow_point(1);" and the subsequent use of "ref_old" inside the loop are unnecessary since you're already handling the assignment of "ref(it)" within the loop.
• When two consecutive "pow_point" values are the same, there's no need for interpolation, and we can assign the value directly to the entire interval between the two consecutive "time_point" corresponding to the same "power_point".
• The final loop that sets "setpoint=yref(s);" doesn't seem to serve a purpose in the context of generating the "ref" sequence, as "setpoint" is overwritten at every iteration and not used elsewhere.

Given these observations, here is a simplified version of the original code that should accomplish the objective:

dt = 1e-4;
T = 200;
n0 = 1;
time = 0:dt:T;
nt = length(time);
ref = zeros(nt, 1);

% Define the time points and corresponding power values
time_point = [0 10 40 70 80 100 110 130 140 150];
pow_point = [0.9 0.9 0.3 0.3 0.9 0.9 0.3 0.3 0.9 0.9];

for i = 1:(length(time_point) - 1)
    % Find the indices in 'time' that correspond to the current and next time points
    startIndex = find(time >= time_point(i), 1, 'first');
    endIndex = find(time < time_point(i + 1), 1, 'last');
    
    % Check if interpolation is necessary
    if pow_point(i) == pow_point(i + 1)
        % Direct assignment if the power values are the same
        ref(startIndex:endIndex) = pow_point(i);
    else
        % Linear interpolation when the power values differ
        for it = startIndex:endIndex
            frac = (time(it) - time_point(i)) / (time_point(i + 1) - time_point(i));
            ref(it) = pow_point(i) * (1 - frac) + pow_point(i + 1) * frac;
        end
    end
end

% Handle the case for the last interval if needed
if time_point(end) <= T
    lastIndex = find(time >= time_point(end), 1, 'first');
    ref(lastIndex:end) = pow_point(end);
end

yref = ref.*n0; % Apply scaling

% Plot the result
figure;
plot(time, yref);
xlabel('Time');
ylabel('Power');

[Kamal]

@Yash Thank you so much fo this insight. This is cool.