Index exceeds the number of array elements (1) error

greetings.

I have asked another question about that topic a time ago but I have the same issue again and I can't find the solution no matter how deep I look at into the program.

I am trying to analyze velocities, accelerations and positions of each link in a mechanism by using Newton Raphson method. I have no issue until the analysis of acceleration matrix and I have the issue stated above in line 65. How can I reconstruct that line for solution?

Thank you for your time.

clc, clear;

%constants
a2=29;a3=15;a4=29;a5=27;a6=25;

%max iteration nr
Nmax=100;

%input:initial guess values th3,th5,th6,to
x=[12*pi/180,61*pi/180,323*pi/180,31];

%Error tolerance
xe=0.001*abs(x);

%System inputs
dth=5*pi/180;
th2=290*pi/180:dth:368*pi/180;
w2=-5*ones(1,length(th2));
al2=0*ones(1,length(th2));

xe=transpose(abs(xe));
kerr=1;
for k=1:1:length(th2)
    for n=1:Nmax
        th3(k)=x(1);th5(k)=x(2);
        th6(k)=x(3);to(k)=x(4);
        
        %Jacobian Matrix
        J=zeros(4,4);
        J(1,1)=-a3*sin(th3(k));J(1,2)=-a4*sin(th5(k)+210*pi/180);
        J(2,1)=a3*cos(th3(k));J(2,2)=a4*cos(th5(k)+210*pi/180);
        J(3,2)=-a5*sin(th5(k));J(3,3)=-a6*sin(th6(k));J(3,4)=-1;
        J(4,2)=a5*cos(th5(k));J(4,3)=a6*cos(th6(k))
        
        %position matrix
       f=zeros(4,1);
       f(1,1)=-(a2*cos(th2(k))+a3*cos(th3(k))+a4*cos(th5(k)+210*pi/180)-43);
       f(2,1)=-(a2*sin(th2(k))+a3*sin(th3(k))+a5*sin(th5(k)+210*pi/180)+33);
       f(3,1)=-(a5*cos(th5(k))+a6*cos(th6(k))-to(k));
       f(4,1)=-(a5*sin(th5(k))+a6*sin(th6(k))-10);
       
       eps=inv(J)*f;
       x=x+transpose(eps);
       
       if abs(eps)<xe
           kerr=0;break
       end
       if kerr==1
           'Error nr'
       end
       th3(k)=x(1);th5(k)=x(2);th6(k)=x(3);to(k)=x(4);
       
       %velocity analysis
       fv=zeros(4,1);
       fv(1,1)=w2(k)*a2.*sin(th2(k));
       fv(2,1)=-w2(k)*a2*cos(th2(k));
       vel=inv(J)*fv;
       w3(k)=vel(1);w5(k)=vel(2);w6=vel(3);vt(k)=vel(4);
       
       %acceleration analysis
       fa=zeros(4,1);
       fa(1,1)=al2(k)*a2*sin(th2(k))-w2(k)^2*a2*cos(th2(k))-w3(k)^2*a3*cos(th3(k))-w5(k)^2*a4*cos(th5(k)+210*pi/180);
       fa(2,1)=-al2(k)*a2*cos(th2(k))+w2(k)^2*a2*sin(th2(k))+w3(k)^2*a3*sin(th3(k))+w5(k)^2*a4*sin(th5(k)+210*pi/180);
       fa(3,1)=w5(k)^2*a5*cos(th5(k))+w6(k)^2*a6*cos(th6(k)); %LINE 65
       fa(4,1)=w5(k)^2*a5*sin(th5(k))+w6(k)^2*a6*sin(th6(k));
       
       acc=inv(J)*fa;
       al3(k)=acc(1);al5(k)=acc(2);
       al6(k)=acc(3);at(k)=acc(4);
       
    end
end
th2d=th2*180/pi;
th3d=th3*180/pi;
th5d=th5*180/pi;
th6d=th6*180/pi;

%--------Plots---------------
figure(1),
subplot(4,3,1),plot(th2d,th4d,'r','linewidth',2),xlabel('\theta_2 (^o)'),ylabel('\theta_3 (^o)'),xlim([300 368])
subplot(4,3,2),plot(th2d,w4,'r','linewidth',2),xlabel('\theta_2 (^o)'),ylabel('\omega_3 (r/s)'),xlim([300 368])
subplot(4,3,3),plot(th2d,al4,'r','linewidth',2),xlabel('\theta_2 (^o)'),ylabel('\alpha_3 (r/s^2)'),xlim([300 368])

subplot(4,3,4),plot(th2d,th5d,'r','linewidth',2),xlabel('\theta_2 (^o)'),ylabel('\theta_5 (^o)'),xlim([300 368])
subplot(4,3,5),plot(th2d,w5,'r','linewidth',2),xlabel('\theta_2 (^o)'),ylabel('\omega_5 (r/s)'),xlim([300 368])
subplot(4,3,6),plot(th2d,al5,'r','linewidth',2),xlabel('\theta_2 (^o)'),ylabel('\alpha_5 (r/s^2)'),xlim([300 368])

subplot(4,3,7),plot(th2d,s,'r','linewidth',2),xlabel('\theta_2 (^o)'),ylabel('\theta_6 (cm)'),xlim([300 368])
subplot(4,3,8),plot(th2d,Vs,'r','linewidth',2),xlabel('\theta_2 (^o)'),ylabel('\omega_6 (cm/s)'),xlim([300 368])
subplot(4,3,9),plot(th2d,as,'r','linewidth',2),xlabel('\theta_2 (^o)'),ylabel('\alpha_6 (cm/s^2)'),xlim([300 368])

subplot(4,3,10),plot(th2d,to,'r','linewidth',2),xlabel('\theta_2 (^o)'),ylabel('t (cm)'),xlim([300 368])
subplot(4,3,11),plot(th2d,Vt,'r','linewidth',2),xlabel('\theta_2 (^o)'),ylabel('V_t (cm/s)'),xlim([300 368])
subplot(4,3,12),plot(th2d,at,'r','linewidth',2),xlabel('\theta_2 (^o)'),ylabel('a_t (cm/s^2)'),xlim([300 368])

Answer 1

[Aoi Midori]

I assumed that you wanted to write in LINE 59 as:

w3(k)=vel(1);w5(k)=vel(2);w6(k)=vel(3);vt(k)=vel(4);

where it's not w6=vel(3) but w6(k)=vel(3), otherwise w6 would be just a scalar and you wouldn't be able to access to w6(k) as you wrote in LINE 65.