How to smooth the plot graph?

Hello everyone,

i need help on how to smoothen the ouput graph

here is the code :

i=0;
thetaf = -0.005054045; % final angle
for t = 0:0.01:0.1  % 1 phase
 tf=0.1; % final time
theta0 = 0.00885953175658278; %initial angle 
a0 = theta0;
  i = i+1;
a1 = 0; % velocity value
a2 = (3/tf^2)*(thetaf-theta0); % cubic coefficient
a3 = (-2/tf^3)*(thetaf-theta0); %cubic coefficient
time(i,1) = t;
theta(i,1) = a0 + a1*t + a2*t^2 + a3*t^3; %position
% thetadot(i,1) = a1 + 2*a2*t + 3*a3*t^2;   % velocity
% thetaddot(i,1) = 2*a2 + 6*a3*t;           % acceleration
end

for t = 0.2:0.01:0.3 % 2 phase
 tf=0.3;
theta0 = 0.105469202; %initial angle 
a4 = theta0;
a5 = 0.966096702; %velocity
a6 = (3/tf^2)*(thetaf-theta0);
a7 = (-2/tf^3)*(thetaf-theta0);
  i = i+1;
time(i,1) = t;
 theta(i,1) = a4 + a5*t + a6*t^2 + a7*t^3; %position
% thetadot(i,1) = a5 + 2*a6*t + 3*a7*t^2;   % velocity
% thetaddot(i,1) = 2*a6 + 6*a7*t;    % acceleration
 end
 
  for t = 0.4:0.01:0.5 % 3 phase
 tf=0.5;
 theta0 = 0.079567522; %initial angle 
a8 = theta0;
a9 = -0.1295084;
a10 = (3/tf^2)*(thetaf-theta0);
a11 = (-2/tf^3)*(thetaf-theta0);
  i = i+1;
time(i,1) = t;
theta(i,1) = a8 + a9*t + a10*t^2 + a11*t^3; %position
% thetadot(i,1) = a9 + 2*a10*t + 3*a11*t^2;   % velocity
% thetaddot(i,1) = 2*a10 + 6*a11*t;      % acceleration
  end
 
 for t = 0.6:0.01:0.65 % 4 phase
 tf=0.6;
 theta0 = 0.040306469; %initial angle 
a12 = theta0;
a13 = -0.196305266; % velocity value
a14 = (3/tf^2)*(thetaf-theta0);
a15 = (-2/tf^3)*(thetaf-theta0);
  i = i+1;
time(i,1) = t;
 theta(i,1) = a12 + a13*t + a14*t^2 + a15*t^3; %position
% thetadot(i,1) = a13 + 2*a14*t + 3*a15*t^2;   % velocity
% thetaddot(i,1) = 2*a14 + 6*a15*t;       % acceleration
 end
 
 for t = 0.70:0.01:0.73 % 5 phase
tf=0.73;
theta0 = -0.074996897; %initial angle 
a16 = theta0;
a17 = -1.153033654; % velocity value
a18 = (3/tf^2)*(thetaf-theta0);
a19 = (-2/tf^3)*(thetaf-theta0);
  i = i+1;
time(i,1) = t;
 theta(i,1) = a16 + a17*t + a18*t^2 + a19*t^3; %position
% thetadot(i,1) = a17 + 2*a18*t + 3*a19*t^2;   % velocity
% thetaddot(i,1) = 2*a18 + 6*a19*t;      % acceleration
 end
 
 for t = 0.80:0.01:0.87 % 6 phase
tf=0.87;
theta0 = -0.043367639; %initial angle 
a20 = theta0;
a21 = 0.24330198; % velocity value
a22 = (3/tf^2)*(thetaf-theta0);
a23 = (-2/tf^3)*(thetaf-theta0);
  i = i+1;
time(i,1) = t;
 theta(i,1) = a20 + a21*t + a22*t^2 + a23*t^3; %position
% thetadot(i,1) = a21 + 2*a22*t + 3*a23*t^2;   % velocity
% thetaddot(i,1) = 2*a22 + 6*a23*t;      % acceleration
 end
 
for t = 0.9:0.01:1 % 7 phase
tf=1;
theta0 = 0.002141521; %initial angle 
a24 = theta0;
a25 =  0.325065431; % velocity value
a26 = (3/tf^2)*(thetaf-theta0);
a27 = (-2/tf^3)*(thetaf-theta0);
  i = i+1;
time(i,1) = t;
theta(i,1) = a24 + a25*t + a26*t^2 + a27*t^3; %position
% thetadot(i,1) = a25 + 2*a26*t + 3*a27*t^2;   % velocity
% thetaddot(i,1) = 2*a26 + 6*a27*t;       % acceleration
end

figure(1)
plot(time,theta)
xlabel('Time(t,sec)','FontSize',14)
ylabel('Angle(degrees)','FontSize',14)
title('\it{Position Profile for Hip}','FontSize',16)

Answer 1

[Erivelton Gualter]

After you plot the position profile add the following code:

for i=5:30;
    p = polyfit(time, theta,i);
    y1 = polyval(p,time);
    cla;
    plot(time,theta, time, y1)
    pause;
end

This is basic a polynomial fit data function.

So for each iteration it will fit a polynomial of degree i. (You need to press enter to continue). Then you can select the best polynomial order.

For example, if you chose 30th, you can add the following code:

p = polyfit(time, theta,30);
y1 = polyval(p,time);
figure;
plot(time,theta, time, y1)