plot the fourbar mechanism in matlab

main.m
% Define link lengths
a = 4; b = 6; c = 8; d = 5;

% Define joint angles
theta2 = linspace(0,2*pi,100); % crank angle
theta3 = zeros(size(theta2)); % coupler angle
theta4 = zeros(size(theta2)); % rocker angle

% Perform kinematic analysis
for i = 1:length(theta2)
    % Solve for theta3 using Grashof's criterion
    A = cos(theta2(i))+d/c;
    B = -2*a*d/c*sin(theta2(i));
    C = (a^2-d^2/c^2);
    Delta = B^2-4*A*C;
    if Delta >= 0
        theta3(i,:) = 2*atan((-B-sqrt(Delta))/(2*A));
    end
    % Solve for theta4 using triangle similarity
    theta4(i,:) = atan(b*sin(theta3(i,:))/(a+b*cos(theta3(i,:)))) + theta3(i,:);
end

% Plot mechanism
x0 = 0; y0 = 0;
x1 = a*cos(theta2);
y1 = a*sin(theta2);
x2 = x1 + b*cos(theta3);
y2 = y1 + b*sin(theta3);
x3 = x0 + d*cos(theta4);
y3 = y0 + d*sin(theta4);

figure;
subplot(1,2,1);
plot([x0 x1],[y0 y1],'k','linewidth',2); hold on;
plot([x1 x2],[y1 y2],'r','linewidth',2);
plot([x2 x3],[y2 y3],'b','linewidth',2);
xlim([-10 10]); ylim([-10 10]); axis equal;

subplot(1,2,2);
plot(theta2*180/pi,theta3*180/pi,'r','linewidth',2); hold on;
plot(theta2*180/pi,theta4*180/pi,'b','linewidth',2);
legend('\theta_3','\theta_4'); xlabel('\theta_2 (deg)'); ylabel('Angle (deg)');
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