Index exceeds the number of array elements (0).

I keep getting the error mentioned above. Index exceeds the number of array elements (0). Error (line 46) T4=RobotConv (0,L(k),0,0);

I have been trying to fix this but cannot get it to work. Does anyone have any tips on this?

clc;

clear all;

display('Joint 1');

display('=======================');

angle1=input('Please key in theta_1 (degree):');

d1=input('Please key in distance_1 (d):');

al1=input('Please key in alpha_1 (degree):');

display('Joint 2');

display('=======================');

angle2=input('Please key in theta_2 (degree):');

d2=input('Please key in distance_2 (d):');

al2=input('Please key in alpha_2 (degree):');

display('Joint 3');

display('=======================');

angle3=input('Please key in theta_3 (degree):');

d3=input('Please key in the minimum distance_3 (d):');

d4=input('Please key in the maximum distance_3 (d):');

al3=input('Please key in alpha_3 (degree):');

display('Joint 4');

display('=======================');

angle4=input('Please key in theta_4 (degree):');

d4=input('Please key in distance_4 (d):');

al4=input('Please key in alpha_4 (degree):');

L1=min(d3);

L2=max(d4);

L3=d4;

theta1=0:angle1/100:angle1;

theta2=0:angle2/100:angle2;

theta3=0:angle3/100:angle3;

L=L2:(L3-L2)/100:L3;

framemax=100;

M=moviein(framemax);

set(gcf,'Position',[100 100 640 480]);

for k=1:framemax

T1=RobotConv(theta1(k), d1, 0, al1);

T2=RobotConv(theta2(k), d2, 0, al2);

T3=RobotConv(theta3(k), d3, 0, al3);

T4=RobotConv(0, L(k), 0, 0);

p0=[0 0 0];

p1=RobotPosition(T1);

p2=RobotPosition(T1*T2);

p3=RobotPosition(T1*T2*T3);

p4=RobotPosition(T1*T2*T3*T4);

figure(1)

X=[p0(1) p1(1) p2(1) p3(1)];

Y=[p0(2) p1(2) p2(2) p3(2)];

Z=[p0(3) p1(3) p2(3) p3(3)];

subplot(221),plot3(X,Y,Z,'o-')

axis([-10 10 -10 10 0 10]);

grid

subplot(222),plot(X,Y,'o-')

axis([-10 10 -10 10]);

title('X-Y')

grid

subplot(223),plot(X,Z,'o-')

axis([-10 10 0 10]);

title('X-Z')

grid

subplot(224),plot(Y,Z,'o-')

axis([-10 10 0 10]);

title('Y-Z')

grid

M(k)=getframe(gcf);

end

function P = RobotPosition(T)

x = T(1,4);

y = T(2,4);

z = T(3,4);

P = [x y z];

end

function T = RobotConv(theta,d,a,alpha)

rad = pi/180;

M_theta = [cos(theta*rad) -sin(theta*rad) 0 0;sin(theta*rad) cos(theta*rad) 0 0;0 0 1 0;0 0 0 1];

M_d = [1 0 0 0;0 1 0 0;0 0 1 d;0 0 0 1];

M_a = [1 0 0 a;0 1 0 0;0 0 1 0;0 0 0 1];

M_alpha = [1 0 0 0;0 cos(alpha*rad) -sin(alpha*rad) 0;0 sin(alpha*rad) cos(alpha*rad) 0; 0 0 0 1];

T=M_theta*M_d*M_a*M_alpha;

end

Answer 1

[Rushil]

Hi Preston

Since the error occurs in the following line (in Line 46), it may be due to accessing the “k” th index of “L”:

T4=RobotConv(0, L(k), 0, 0);

The array “L” is initialized using “L2” and ”L3” (in Line 37) as follows:

L=L2:(L3-L2)/100:L3;

The error probably occurs due to “L” being an empty array. Perhaps you can investigate the size of “L”, and further, the values of “L2” and “L3”.

Moreover, a problem very similar to this has been discussed at the following link:

https://mathworks.com/matlabcentral/answers/509616-index-exceeds-the-number-of-array-elements-0

I hope you are able to resolve the problem and proceed.

larush