As promised, here is some of the Matlab code for the Theo Jansen Mechanism we posted a video of a little while back. We begin every Matlab program with the clear all command. Next are the lengths for all of the linkages.
clear all
%Link Lengths
L1=286;
L2=120;
L3=400;
L4=275;
L5=400;
L6=290;
L7=275;
L8=275;
L9=400;
L10=290;
L11=400;
L12=275;
L13=170;
%To get the video output:
a=1;
mov=avifile('TheoJansen.avi','COMPRESSION','None');
for theta=0:pi/20:8*pi
%Relating all values to theta2 of 4-bar mechanism O2ABO1
theta2=pi-theta;
ssquared=(L2)^2+(L1)^2-(2*L1*L2*cos(theta2));
s=sqrt(ssquared);
beta=asin((L2*sin(theta2))/s);
psi=acos(((L3^2)+(s^2)-(L4^2))/(2*L3*s));
lambda=acos((L4^2+s^2-L3^2)/(2*L4*s));
theta3=pi-psi+beta;
theta4=pi+beta+lambda;
theta5=lambda+beta;
%Finding the points relative to the motion of theta2
O1=[0,0];
O2=[-L1,0];
A=[L2*cos(theta) L2*sin(theta)];
B=[A(1)-L3*cos(psi-beta) A(2)+L3*sin(psi-beta)];
%Plotting the 4-bar mechanism
plot ([O1(1),A(1)],[O1(2),A(2)],'r','linewidth',3)
hold on
plot ([O2(1),O1(1)],[O2(2),O1(2)],'black','linewidth',3)
plot ([A(1),B(1)],[A(2),B(2)],'g','linewidth',3)
plot ([O2(1),B(1)],[O2(2),B(2)],'r','linewidth',3)
%Bottom triangle DEF
F=[E(1)-L12*cos(lambda+beta) E(2)-L12*sin(lambda+beta)];
plot([D(1),F(1)],[D(2),F(2)],'linewidth',3)
plot([E(1),F(1)],[E(2),F(2)],'linewidth',3)
%Link FG
G=[F(1)-L13*cos(lambda+beta) F(2)-L13*sin(lambda+beta)];
%Trajectory of point G
plot([F(1),G(1)],[F(2),G(2)],'linewidth',3)
Gx(a)=G(1);
Gy(a)=G(2);
plot(Gx,Gy)
axis([-800 400 -800 400])
hold off
a=a+1;
pause(.1)
M=getframe;
mov=addframe(mov,M);
end
mov=close(mov);
I left out a portion in the middle so you'll just have to figure that out by yourself!
