Week 2- 2R Robotic Arm Challenge

% Forward kinematics of a robotic arm
clear all
close all
clc

% Inputs
% length of first link(m)
l1=1;
% length of second link(m)
l2=0.5;
%origin is fixed to the base of the first link coordinate will be (0,0)

% angle of first link
theta1= linspace(0,90,15);
% angle of second link
theta2=linspace(0,90,15);

% initiate the counter value
ct=1;
%using for loop to calculate each position of theta1
for i=1:length(theta1)
    THETA1=theta1(i);
%using for loop to calculate for each position of theta2 for one position
%of theta1

    for j=1:length(theta2)
        THETA2=theta2(j);
%Starting point coordinates of first link
        x0=0;
        y0=0;
    
%End point coordinates of first link and starting point coordinates of second link       
x1= l1*cosd(THETA1);
y1= l1*sind(THETA1);

%End point coordinates of second link
x2= x1+l2*cosd(THETA2);
y2=y1+l2*sind(THETA2);

% Plotting
plot([x0 x1], [y0 y1], [x1 x2], [y1 y2],'linewidth',3)
axis([-0.1 1.5 0 1.5])
pause(0.03)
M(ct)= getframe(gcf);
ct=ct+1;

    end

end

movie(M)
videofile= VideoWriter('forward_kinematics.avi', 'Uncompressed Avi');
open(videofile)
writeVideo(videofile,M)
close(videofile)

Explanation of code:

• Program starts with usual matlab commands clear all close all clc
• Two links are attached by certain angle their inputs are assigned.Length of both the links are entered manually.
• Angles theta 1 & theta 2 are entered with the help of linspace command which takes 10 values between 0 and 90 with common difference of 10.
• Now counter 'ct' value is initiated.It helps in proper indexing in which the captured frames will be indexed sequentially which follows the proper order when comes to movie creation.
• Now nested for loop is used because in robotic arm simulation for a single movement of link-1, we are computing all possible moves of link 2.

1. The value of 'i' is going to change from 1 to length of theta1 and value of 'j' is going to change from 1 to length of theta2.
2. As the values of 'i' & 'j' changes theta1 and theta2 are taken from original arrays and are assigned to variables 'THETA1' and 'THETA2' which contains only one value and not an array.
3. Loop counter variables are used to access particular value.For each position of theta1 means each position of link 1 , link 2 can take multiple positions depens on theta2.

• Enter the values of coordinates ([X0 X1], [Y0 Y1], [X1 X2], [Y1 Y2]).
• Then plot the values of the above coordinates with linewidth 3.
• Now axis command is used for fixing axes- changing x limits and y limits.
• Pause command is used to slow down the output.
• Getframe capture the figures as a frame we use to get individual frame and stored in variable M.
• Then incrementing the counter value by 1.
• End command is used to end for loop, this terminates the set of instructions.
• Movie command helps to play the movie frames in array 'M' once.
• Using the different individual frames a new uncompressed avi file is created using videofile command.
• Then we are opening the videofile using the open command and closing thevideofile using the close command.

Plot: The combination of both links is shown below-

ANIMATION:The link for animation of 2R robotic arm is below:

https://drive.google.com/file/d/1lcg00bNlHISBup4lxIWt6LCWH_R6tDrW/view?usp=sharing

Errors faced while programming:

• The above error was observed because one of the loop was not ended as it's syntax, so an 'end' was put at the end of the for loop.

• Matlab is case sensitive while creating the video use 'VideoWriter' not 'videowriter' or 'Videowriter' or 'videoWriter'.

CONCLUSION:

We can conclude that the area covered by robotic arm is the space of robort that much area can be used for working.

These robots have various industrial application-

• Welding in automobile industry.
• Material handling.
• Assembly operations.
• Machine loading and unloading.
• Spray painting of automobile bodies.