Forward kinematics model using DH parameters in MATLAB

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SUMMARY

The discussion focuses on implementing a forward kinematics model using Denavit-Hartenberg (DH) parameters in MATLAB. The user is seeking guidance on how to input the DH parameters—theta, d, a, and alpha—into the transformation matrix to calculate the end-effector position. The provided MATLAB code includes a function to generate the transformation matrix and another to compute the forward kinematics using specific theta values. The user has defined the necessary DH parameters and is looking for clarification on their application within the transformation matrix.

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  • Understanding of Denavit-Hartenberg (DH) parameters
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Homework Statement
Derive the forward kinematics model in MATLAB using the DH parameters provided.
Relevant Equations
The homogeneous transformation matrix has the form shown in the attached image.
5 links (thus 6 frames) and corresponding theta, alpha, d and a values are all given.
However, I'm not sure how to start coding the DH parameters to derive a forward kinematics model.

I know that I'll have to use matrix operators, but do I just put in the values of the 4 factors mentioned above in the transformation matrix in the attached image and then calculate the transformation matrix from the origin to the end-effector?
Please help. Thanks.
 

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Below is my code. I have all the DH parameters that will allow me to calculate the end effector position.
I'm not sure where to input the values of thetas 1 ~5 shown at the bottom. Please help.

function [T] = getTransformMatrix(theta, d, a, alpha)
T = [cosd(theta) -sind(theta) * cosd(alpha) sind(theta) * sind(alpha) a * cosd(theta);...
sind(theta) cosd(theta) * cosd(alpha) -cosd(theta) * sind(alpha) a * sind(theta);...
0,sind(alpha),cosd(alpha),d;...
0,0,0,1];
end

function [T00,T01,T12,T23,T34,T45,EndEffector] = forwardKinematics(theta1, theta2, theta3, theta4, theta5)T00 = [1 0 0 0; 0 1 0 0; 0 0 1 0; 0 0 0 1];
T01 = getTransformMatrix(theta1,10.25,0,90);
T12 = getTransformMatrix(theta2,0,9,0);
T23 = getTransformMatrix(theta3,0,9,0);
T34 = getTransformMatrix(theta4,0,0,90);
T45 = getTransformMatrix(theta5,6.25,0,0);
EndEffector = T00 * T01 * T12 * T23 * T34 * T45;

end

theta1 = 30;
theta2 = 45;
theta3 = -90;
theta4 = 45;
theta5 = 60;
 
Last edited:

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