Week 3.2 - 2R Robotic Arm Challenge

% Forward Kinematic of a 2R Robotic Arm

clear
close
clc

l1 = 1;                 % Length of link-1
l2 = 0.75;              % Length of link-2   
theta1 = 0:5:90;        % Angle of link-1 to X-axis
theta2 = 0:5:90;        % Angle of link-2 to X-axis
                 
% x0,y0 are coordinates of start point of link-1
% x1,y1 are coordinates of end point of link-1
% coordinates of start point of link-2 will be the end point of link-1
% x2,y2 are coordinates of end point of link-1
x0 = 0;                                    
y0 = 0;

count = 1;
for i=1:length(theta1)
    x1 = l1*cosd(theta1(i));          
    y1 = l1*sind(theta1(i));     
    for j=1:length(theta2) 
        x2 = x1+l2*cosd(theta2(j));     
        y2 = y1+l2*sind(theta2(j));

        figure(1)                                        % Plotting
        plot([x0 x1],[y0 y1],'linewidth',3,'color','r')
        hold on
        plot([x1 x2],[y1 y2],'linewidth',3,'color','g')
        hold off
        axis ([-0.1 2 0 2])

        M(count) = getframe(gcf);           % Saving each frame to create a movie
        count = count+1;
    end
end

movie(M)                                     % Creating the Video file
videofile = VideoWriter('Forward Kinematic of a 2R Robotic Arm.avi','Uncompressed AVI');
open(videofile)
writeVideo(videofile,M)
close(videofile)

REPORT

 

Aim : To simulate the forward kinematics of a 2R Robotic Arm using MATLAB and create an animation file of the plot.

Theory :

A robotic arm is programmable with similar functions to a human arm, it can even perform more complex movements that a human arm may not be able to do. A 2R robotic arm is a two-segment robotic arm with two revolute joints, allowing rotational motion around specific axes.  It is fixed onto a base surface and the contact point acts as the origin through which the axis for the whole arm passes.

 

L1 = Length of link-1

L2 = Length of link-2

(x₀,y₀) = coordinates of start point of link-1 which is the origin = (0,0)

(x₁,y₁) = coordinates of end point of link-1 and the  start point of link-2

(x₂,y₂) = coordinates of end point of link-1

Θ₁ = angle of link-1 to X-axis  = values assigned from 0°-90°

Θ₂ = angle of link-2 to X-axis = values assigned from 0°-90°

Use for-loop top calculate value of (x₁,y₁) and calculate (x₂,y₂)for each value of (x₁,y₁)using a nested for-loop.

Errors that can be found :

1. Without figure(1) command on the first execution creates a new figure window then keeps it activated in every loop. Without it the plot will only show the final output at the end of the nested for-loop.

 

2. Without ‘hold on’ command the window will refresh every time and the red link will not be visible.

 

3. ‘hold off’ command the clear window after execution otherwise all previous plots will be visible.

 

4. The axis([-0.1 2 0 2]) command fixes the origin to a location and restricts window size to the parameter.

 

Code:

 

Output :

https://drive.google.com/file/d/1L4Vhvs12vFLBjew8cI5c8A57QDX8DEpZ/view?usp=drive_link