Unwanted line in graph

I am doing a mobile robot simulation by solving the differential equation using ode solver and an animated line to show the movement of the robot (robot path)

%Simulation Experiment (kinematics input speed)***************
function mydglcallw6(WR,WL,n)
clf;
tspan = [0 2];initials = zeros(n,3); %start at origin 
p = par();
%**************************************************************
%Creating robot path according to input speed****************** 
for i = 1:n   
p.WL = WL(i) ;p.WR = WR(i);  
sol(i)= ode23(@mydglw5, tspan, initials(i,:),[],p);
[t,s] = ode23(@mydglw5, tspan, initials(i,:),[],p);
initials(i+1,:) = deval(sol(i),2);
curve = animatedline(0,0,'Color','r','linewidth',2);
axis([-1.5 1.5 -1.5 1.5]);
xlabel('x-position [m]');ylabel('y-position [m]');
title('robot path');
grid on 
for j = 1:length(s(:,1))
  addpoints(curve,s(j,1),s(j,2))
  drawnow 
  pause(0.02)
end
end
end
%*************************************************************
%Model Parameters*********************************************  
function p = par();
p.L = 0.12;                        %length [m]
p.r = 0.1;                         %radius of wheel [m]
%p.WL = 2;p.WR = 2.5;              %wheel velocities [th/s]
end
%*************************************************************
%Differential Equations*************************************** 
function dt = mydglw5(t,c,p)
x = c(1);y = c(2);th = c(3);
dx = (((p.r*p.WL)+(p.r*p.WR))/2) * cos(th);
dy = (((p.r*p.WL)+(p.r*p.WR))/2) * sin(th);
dth= ((p.r*p.WL)-(p.r*p.WR))/p.L;
dt = [dx;dy;dth];
in = [x(end);y(end);th(end)];     %compare last value with deval 
end

when i use this code, i always get an unwanted line in the graph ?? how can i remove it ?

Answer 1

[Steven Lord]

Is that unwanted line between the point (0, 0) and the first point in the solution? [I would run the code to see, but you didn't tell us what WR, WL, or n are.] If so try creating the animatedline starting with the point (NaN, NaN). Like most if not all of the plotting functions in MATLAB, points with one or both of the coordinates NaN are not displayed by an animatedline.

h = animatedline(NaN, NaN, 'Color', 'r');
axis([-10 370 -1 1]);
for k = 0:360
  addpoints(h, k, cosd(k))
  pause(0.01)
end

Compare that with:

figure
h = animatedline(0, 0, 'Color', 'r');
axis([-10 370 -1 1]);
for k = 0:360
  addpoints(h, k, cosd(k))
  pause(0.01)
end

If that's not the unwanted line you're seeing, please describe in more detail where the unwanted line is located (and/or give us a small sample of data for WR, WL, and n so we can run your example) and we may be able to offer other suggestions.

[Moustafa Aboubakr]

Thanks Steven for your answer, i removed the (0,0) and it worked :) curve = animatedline('Color','r','linewidth',2); WR & WL are the input velocities of the wheels and n is the number of times the differential equation is solved ex: mydglcallw6([1.5 2 2.5 3.5],[2 2.5 3 3.5],4) Thanks again :)

Answer 2

[Moustafa Aboubakr]

I removed the (0,0) and it worked :) curve = animatedline('Color','r','linewidth',2); WR & WL are the input velocities of the wheels and n is the number of times the differential equation is solved ex: mydglcallw6([1.5 2 2.5 3.5],[2 2.5 3 3.5],4)