# RV-M1 inverse kinematics

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Jose Maria Braga on 21 Oct 2019
Commented: Jose Maria Braga on 22 Apr 2021
Hi! I am trying to instruct RV-M1, a 5-DOF manipulator, to write the letters EEE on a paper. First, I explicitly defined the points of all vertices of EEE, including the intermediate points when traversing the spaces between each E. Next, I defined the cost function with inputs joint angles and defined points, cost(joint_angles,defined_points). The cost function is defined as the square of the difference between computed points and the explicitly defined points. That is, cost = (computed - defined)^2. The computed points are computed using the forward kinematic equations. I now feed the defined points to fmincon. The parameters of fmincon are:
Aeq = [0 1 1 1];
beq = 0
lower and upper bounds of the four joint angles, the last angle is always zero
lb = [-145; -25; -105; -85]
ub= [145; 95; 0; 85]
initial_angles = [0 0 0 0]
fmincon(@(joint_angles) cost(joint_angles, defined points), initial_angles,[],[],Aeq,beq,lb,ub)
However, the joint space I'm getting does not correspond to my explicitly defined points. Where am I wrong? I am happy to send my code if someone can help me.

Dario Andres Gomez Campos on 19 Apr 2021
Hello, I do not know if you are still interested, but you can check my work in we solve this robot with inverse and direct kinematics.
Greetings,
Jose Maria Braga on 22 Apr 2021
Thank you! This is great! Coming from the Philippines, I can understand some Spanish words but, do you, by any chance, have an English version of the manuscript? This is an interesting reading :)