Simple 3-DOF Planar Parallel Robot in Simulink environment

Kaixian QU

- Model display

This robot is made of 2-DOF Planar Parallel Robot with 1-DOF pencil on the vertical plane. The goal is to control 2 motors to drive the pencil go along a straight line, and another motor to make pencil up and down. My Simulink model consists of 6 modules(see picture below). - Trajectory display

The pencil goes along a straight line from (0, 0.3, 0.05) to (0.3, 0.5, -0.05) in 5 seconds

I also tested its straightness via Curve Fitting Tool. As you can see, the R-square is 1, which means that the trajectory is perfectly straight. - Function solving inverse kinematics
len1 = .35; len2 = .35; len3 = .35; len4 = .35; l = .6; syms x y theta1 theta2 theta4 theta5 eqyl = (len1 * sin(theta1) + len2 * sin(theta1 + theta2) == y); eqyr = (len3 * sin(theta4 + theta5) + len4 * sin(theta5) == y); eqxl = (len1 * cos(theta1) + len2 * cos(theta1 + theta2) == x); eqxr = (len3 * cos(theta4 + theta5) + len4 * cos(theta5) == l - x); [theta1, theta2, theta4, theta5] = solve(eqxl, eqyl, eqxr, eqyr, theta1, theta2, theta4, theta5); theta1 theta5

Given the expected values of X, Y coordinates, this function outputs the required value of 2 motor angles.

function [theta5,theta1] = fcn(x, y) theta1 = 2*atan((7*y + (x^2*(-(x^2 + y^2)*(100*x^2 + 100*y^2 - 49))^(1/2)) ... /(x^2 + y^2) + (y^2*(-(x^2 + y^2)*(100*x^2 + 100*y^2 - 49))^(1/2))... /(x^2 + y^2))/(10*x^2 + 7*x + 10*y^2)); theta5 = 2*atan((35*y + ((25*x^2 - 30*x + 25*y^2 + 9)*... (- 100*x^2 + 120*x - 100*y^2 + 13))^(1/2))/(50*x^2 - 95*x + 50*y^2 + 39)); end

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I cannot imagine how proud I would be in the future introducing my robotics project to others, especially my beloved one.

I wil have all my working stuff organized in a perfect way that others may never understand, whereas I shall always be proud of this personality.

I can machine anything I need in that lab, with no need to ask others for helping me produce some workpiece.

Comparing to other major, I know robotics is not a fully developed area, which means that we shall work really hard to make little progress. However, that is the reason why so many others are so obsessed with it, because we are trying to push the boundaries of robotics, thus improving lives of human beings and shaping our future.

I want to be a roboticist, to be one of the best, and to create the best robots for me, for my university, and most importantly, for our world!

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