Our BOM and various supporting codes are found in here.

Bill of Materials:

• ½” Hex Shaft (x2)
• ½” Hex Bushings (x4, 3D Printed)
• Pinion Gear (x1, 3D Printed)
• 4:1 Step Gears (x2, 3D Printed)
• 5:1 Step Gears (x2, 3D Printed)
• 100 RPM Greartisan DC motor (x1)
• 8-32 bolts and locknuts (x14 of each)
• Chassis Panels (laser-cut)
• Fourbar Linkages (x12 total, laser-cut)
• Acrylic Spacers (x12)

Code

Main Code

l = [4, 1, 4.2, 1.5];

theta_2 = -1:1:360;

omega_2 = 100;

% gear ratio

omega_output = omega_2/20;

len = length(theta_2);

% position analysis matrices

xRockerPos = zeros(1,len);

yRockerPos = zeros(1,len);

xArmPos = zeros(1,len);

yArmPos = zeros(1,len);

xHookPos = zeros(1,len);

yHookPos = zeros(1,len);

% mechanical advantage matrix

MA = zeros(1,len);

% velocity analysis matrices

RockerVelo = zeros(1,len);

HookVelo = zeros(1,len);

for i = 1:1:len

%     disp(i);

   [theta_3,theta_4] = fourbarpos(l,0,theta_2(i),-1);

%     disp(theta_3);

%     disp(theta_4);

   xRockerPos(i) = l(4)*sind(theta_4-90);

   yRockerPos(i) = l(4)*cosd(theta_4-90);

   xArmPos(i) = (l(2)*cosd(theta_2(i)))+(l(3)+3.08)*cosd(theta_3);

   yArmPos(i) = (l(2)*sind(theta_2(i)))+(l(3)+3.08)*sind(theta_3);

   xHookPos(i) = (l(2)*cosd(theta_2(i)))+(l(3)+3.08)*cosd(theta_3)+((3.688)*cosd(theta_3-90));

   yHookPos(i) = (l(2)*sind(theta_2(i)))+(l(3)+3.08)*sind(theta_3)+((3.688)*sind(theta_3-90));

   MA(i) = FinalProject_MA_Function(l,0,theta_2(i));

   [omega_3,omega_4] = fourbarvelo(l,0,theta_2(i), theta_3, theta_4, omega_output);

   RockerVelo(i) = omega_4*l(4);

   HookVelo(i) = omega_3*sqrt((xHookPos(i)^2)+(yHookPos(i)^2));

end

% figure(1)

% plot3(xRockerPos,yRockerPos,theta_2);

% title('Rocker Motion');

% xlabel('X-Position of Rocker (in)');

% ylabel('Y-Position of Rocker (in)');

% zlabel('Theta_2');

% grid on

% figure(2)

% plot3(xArmPos,yArmPos,theta_2);

% title('Arm Tip Motion');

% xlabel('X-Position of Arm End (in)');

% ylabel('Y-Position of Arm End (in)');

% zlabel('Theta_2');

% grid on

figure(3)

plot3(xHookPos,yHookPos,theta_2);

title('Hook Tip Motion');

xlabel('X-Position of Hook Tip (in)');

ylabel('Y-Position of Hook Tip (in)');

zlabel('Theta_2');

grid on

% view(0,90)  % XY

% pause

% view(0,0)   % XZ

% pause

% view(90,0)  % YZ

figure(4)

plot(theta_2,MA)

title('Mechanical Advantage vs. Theta_2');

xlabel('Theta_2');

ylabel('Mechanical Advantage');

grid on

% figure(5)

% plot(theta_2,RockerVelo);

% title('Rocker Velocity vs. Theta_2');

% xlabel('Theta_2');

% ylabel('Rocker Velocity (in/s)');

% grid on

figure(6)

plot(theta_2,HookVelo);

title('Hook Velocity vs. Theta_2');

xlabel('Theta_2');

ylabel('Hook Velocity (in/s)');

grid on

“fourbarpos” Function

function [theta_3, theta_4] = fourbarpos(l,theta_1,theta_2,delta)

% define bar lengths

a = l(2);

b = l(3);

c = l(4);

d = l(1);

% theta_1_r = deg2rad(theta_1);

% theta_2_r = deg2rad(theta_2);

% define K values

K1 = d/a;

K2 = d/c;

K3 = ((a^2)-(b^2)+(c^2)+(d^2))/(2*a*c);

% calculate A B C

A = cosd(theta_2) - K1 - (K2*cosd(theta_2)) + K3;

B = (-2)*sind(theta_2);

C = K1 - ((K2+1)*cosd(theta_2)) + K3;

% calculate theta_4

theta_4 = 2*atand((-B+(delta*sqrt((B^2)-(4*A*C))))/(2*A));

% calculate theta_3

theta_3 = asind(((c*sind(theta_4))-(a*sind(theta_2)))/b);

% display angle values

% fprintf("Angle 3 = %.3f\n", theta_3);

% fprintf("Angle 4 = %.3f\n", theta_4);

“fourbarvelo” Function

function [omega_3, omega_4] = fourbarvelo(l,theta_1,theta_2, theta_3, theta_4, omega_2)

a = l(1);

b = l(2);

c = l(3);

d = l(4);

omega_3 = omega_2*(a/b)*((sind(theta_4-theta_2))/(sind(theta_3-theta_4)));

omega_4 = omega_2*(a/c)*((sind(theta_2-theta_3))/(sind(theta_4-theta_3)));

% fprintf("Omega 3 = %.3f\n", omega_3);

% fprintf("Omega 4 = %.3f\n", omega_4);

“FinalProject_MA_Function” Function

function [MA] = FinalProject_MA_Function(l,theta_1,theta_2)

% define bar lengths

a = l(1);

b = l(2);

c = l(3);

d = l(4);

% find MA for each angle step

L_BD = sqrt((b^2) + (a^2) - (2*b*a*cosd(theta_2)));

gamma = acosd(-((L_BD^2) - (c^2) - (d^2))/(2*c*d));

beta_1 = acosd(-((a^2) - (b^2) - (L_BD^2))/(2*b*L_BD));

beta_2 = acosd(-((d^2) - (c^2) - (L_BD^2))/(2*c*L_BD));

beta = beta_1 + beta_2;

MA = (d*sind(gamma))/(b*sind(beta));