Week 2- 2R Robotic Arm Challenge

%A program of forward kinematics of a 2R Robotic Arm

%Input

%length

L1= 1.5;

L2= 0.7;

%Angle

theta1 = [linspace(0,90,40)];

theta2 = [linspace(0,90,50)];

% initiate the counter value

ct=1;

for

i=1:length(theta1)

THETA1 =theta1(i);

for

j=1:length (theta2)

THETA2 = theta2(j);

%Coordinates

x0 = 0;

y0 = 0;

x1 = L1*cosd(THETA1);

y1 = L1*sind(THETA1);

x2 = x1+L2*cosd(THETA2);

y2 = y1+L2*sind(THETA2);

%plotting

plot([x0,x1],[y0,y1],[x1,x2],[y1,y2],'linewidth',3)

axis([-0.1,2.5,0,2.5])

pause(0.01)

M(ct) = getframe(gcf);

ct=ct+1;

end

end

movie(M)

videoFile=VideoWriter('Forward Kinemetics .avi','Uncompressed AVI');

open(videoFile)

writeVideo(videoFile,M)

close(videoFile)

Code Explanation:-

Before writing the code, it's important to start with clear all, close all and clc commands since

Clear all - removes data from the workspace, freeing up system memory

Close all- deletes the current figure or the specified figure

clc - clears all input and output from the Command Window display, giving you a "clean screen

Next step for the code is to define the inputs and its values. Length of arm 1 and arm 2 were both defined. both theta 1 and theta 2 were defined by using the 'linspace' command. The function of the linspace generates linearly spaced vectors. So in the case of theta 1 and theta 2, linspace(0,90,10) means that Matlab will generate a row vector 90 of 10 points linearly spaced between and including 0 and 90.

The next step is to set up a counter. A counter is a variable that counts an event in a loop. A for loop was used for this project, a for loop is a repetition control structure that allows you to efficiently write a loop that needs to execute a specific number of times.

Since theta 1 and theta 2 will contain multiple values of the angle within the x-axis, a new variable is needed inside the for loop for both x and y coordinates. THETA 1 and THETA 2 are added to the code, for THETA 2 the variable j was added instead of i as this will give THETA 2 its own respective angle. The formula for calculating x1, y1, x2 and y2 are shown in figure 2.

The next step is to plot the graph for all the x and y coordinates with axis shown above in figure 3. A pause command was used for pausing the command for a certain time, for this project a pause of 0.03 s was used. The M command was used to capture the current frame every time the for loop runs. The final step of the loop is to add a +1 to the ct variable; this will increment the frame every time the for loop run. End command was used for the plot and for the for loop to stop both from running.

The final step of the code is to create a movie of the animation of the robotic arm, so the movie command was used. The VideoWriter command was used to assign the video format, for this project .avi was used as the format. The open command was used to open the video. writevideo command was used to write the video with plot frames. Finally, the close command was used to close the video file.

Errors faced while programming:-

Error in alternateGetframe

Error in getframe (line 71)
x = alternateGetframe(parentFig, offsetRect, scaledOffsetRect, includeDecorations, true, h, offsetRectSpecified);

Error in Roboticarm (line 38)
M(ct) = getframe(gcf);

USE OF THE FOLLOWING FUNCTIONS USED WHILE PROGRAMMING

FOR LOOP- For loop is used here for the iteration of the theta values from 0 to 90 degrees I is used as the outer loop and J is used as the inner loop ,i is used for the movement of the link 1 and J is used for the movement of link 2.

COSD and SIND are used to covert the Radians into Degrees,because MATLAB by default takes angles in radians.

PAUSE - We have paused the code so that the process can be visualised more clearly .

Ct-Ct is used for saving the frames in order to create a movie of the frames

Getframe-Similarly getframe is used to capture the frame and then by fast movement of those frames it can be converted into a movie

Movie -Movie command is used to create a movie of the frames captured .

VideoWriter -It is to create a Video file of the movie created and save in the pc hard disc.

Plot - The plot command is used to plot the graphs of the coordinates provided.

Axis- The axis command is used to create the axis upon which we are going to plot the coordinates.

Linspace-The linspace command is useful in creating an array of values specified by the user.

RESULT:- https://youtu.be/MOjMGgy2Vxc