plot data into a while lopp without storing the data

Hello,

I have a while loop that iterates 2500 times and in each loop I get 3 arrays of 6x1. I dont want to store the data for each iteration, only plot the actual data and keep updating the same plot... is that possible??

Thanks in advance

[Ankit]

yes it is possible.. how your code looks like?

[mikel lasa]

%% INIT
clear all;
close all;
clc;
%% loop img
img = imread('bucle_PD.PNG');
imshow(img)
%% Load paths and regressor functions
% load paths from .MAT file
paths=load('robot_path.mat','pos','vel','acc'); % 
n=6;
for i=1:n
    pos(i)=paths.pos(1,i);
    vel(i)=paths.vel(1,i);
    acc(i)=paths.acc(1,i);
end
% load regressor functions
fregs=load('fregs.mat','fregFric','fregG','fregCentrCorG','fregCentrCor','fregM');
fregFric=fregs.fregFric;
fregG=fregs.fregG;
fregCentrCorG=fregs.fregCentrCorG;
fregCentrCor=fregs.fregCentrCor;
fregM=fregs.fregM;
%% set boundaries
%T0=0;
Hzloop = rateControl(200);
%tloop=0.005; %loop time rate
Hztdynamics = rateControl(50);
%tdynamics= 0.02; %dynamic parameters refresh rate
Kp=1;
Kv=1;
deltaT=0.004;
%% Loop computation
E1=[];
Efeedback=[0;0;0;0;0;0];
E2=[0,0,0,0,0,0];
k=0;
qs=[];
while k <= 10
    k= k+1;
    for i=1:length(acc{1})
        % comienza desde estado 0 de robot (q=0, qd= 0, qdd=0)
        % E2 corresponde al calculo de la salida del robot*dinamica
        E2=fregCentrCorG(vel{1}(1,i),vel{2}(1,i),vel{3}(1,i),vel{4}(1,i),vel{5}(1,i),vel{6}(1,i),pos{2}(1,i),pos{3}(1,i),pos{4}(1,i),pos{5}(1,i),pos{6}(1,i))+fregG(pos{2}(1,i),pos{3}(1,i),pos{4}(1,i),pos{5}(1,i),pos{6}(1,i))+fregFric(vel{1}(1,i),vel{2}(1,i),vel{3}(1,i),vel{4}(1,i),vel{5}(1,i),vel{6}(1,i));
        %calculo de E1
        for j=1:n
            %Efeed es la primera resta que viene del feedback
            Efeedback(j,1)=(pos{j}(1,i)-Efeedback(j,1));
            E1(j,1)=acc{j}(1,i)+(vel{j}(1,i)-Efeedback(j,1))*Kv+Efeedback(j,1)*Kp;
        end
        %calculo de la matriz M
        EM= fregM(E1(2,1),E1(3,1),E1(4,1),E1(5,1),E1(6,1));
        % calcular los torques
        torque=EM*E2;
        %con el torque calculado, calcular la thetadd de salida

   qdd= inv(EM)*(torque-E2);
        %calcular thetad siguiente
        for indx=1:n
            qds=vel{indx}(1,i)+deltaT*qdd;
            % calcular thetas
            qs(indx,1)=pos{indx}(1,i)+deltaT*vel{indx}(1,i);
        end
        %cerrar el bucle
        
    end
end

I want to plot just the las 3 variables:

qdd

qds

qs

Answer 1

[Voss]

If you want each new iteration to replace previously plotted results:

i = 0
while i < 2500
    % do stuff
    
    hold off
    plot(x)
    hold on
    plot(y)
    plot(z)
    drawnow()
    
    i = i+1;
end

If you want each new iteration to add to the previously plotted results:

hold on

i = 0
while i < 2500
    % do stuff
    
    plot(x)
    plot(y)
    plot(z)
    drawnow()
    
    i = i+1;
end

[mikel lasa]

I have taken the 2 script and even if I see the plot updating for each loop with good values in the axis, the plot is empty.

 %% Loop computation
 E1=[];
 Efeedback=[0;0;0;0;0;0];
 E2=[0,0,0,0,0,0];
 k=0;
 qs=[];

 t=linspace(0,10,2500);
figure()
hold on
while k <= 10
    
    for i=1:length(zacc{1})
        % comienza desde estado 0 de robot (q=0, qd= 0, qdd=0)
        % E2 corresponde al calculo de la salida del robot*dinamica
        E2=fregCentrCorG(zvel{1}(1,i),zvel{2}(1,i),zvel{3}(1,i),zvel{4}(1,i),zvel{5}(1,i),zvel{6}(1,i),zpos{2}(1,i),zpos{3}(1,i),zpos{4}(1,i),zpos{5}(1,i),zpos{6}(1,i))+fregG(zpos{2}(1,i),zpos{3}(1,i),zpos{4}(1,i),zpos{5}(1,i),zpos{6}(1,i))+fregFric(zvel{1}(1,i),zvel{2}(1,i),zvel{3}(1,i),zvel{4}(1,i),zvel{5}(1,i),zvel{6}(1,i));

        %calculo de E1
        for j=1:n
            %Efeed es la primera resta que viene del feedback
            Efeedback(j,1)=(zpos{j}(1,i)-Efeedback(j,1));
            E1(j,1)=zacc{j}(1,i)+(zvel{j}(1,i)-Efeedback(j,1))*Kv+Efeedback(j,1)*Kp;
        end
        %calculo de la matriz M
        EM= fregM(E1(2,1),E1(3,1),E1(4,1),E1(5,1),E1(6,1));
        % calcular los torques
        torque=EM*E2;

        %con el torque calculado, calcular la thetadd de salida
        qdd= inv(EM)*(torque-E2);

        %calcular thetad siguiente
        for indx=1:n
            qds=zvel{indx}(1,i)+deltaT*qdd;

            % calcular thetas
            qs(indx,1)=zpos{indx}(1,i)+deltaT*zvel{indx}(1,i);
            
        end
        %cerrar el bucle
            plot(i,qs(1,1))
            hold on
            drawnow
            k= k+1;
    end
end

[Voss]

The line:

plot(i,qs(1,1))

plots one point. What happens if you replace that with this:

plot(qs(:,1))

or perhaps this:

plot(i*ones(n,1),qs(:,1))

Try those and see if it's more like what you want.

(And if you attach the necessary mat files, I'll be able to run the code and provide more useful help.)

[mikel lasa]

Hello,

sorry for the late asnwer, I was out for a couple of days.

I've tried to apply your plot lines but no success. I've attached my mat files to help you.

EDIT: using plot(i*ones(n,1),qs(:,1)) works, dont know why but using the default settigns it doesnt plot anything.

I tried to add 'o' to the plot (i*ones(n,1),qs(:,1),'o') and works now

Thanks!