# Robotic arm control

1. Nov 26, 2012

### ffp

βHi, i'm working in a project with an arduino mega 2560 controling a robotic arm with 2 DOF moved by servo motors.

I want to make the arm lift vertically about 20 cm as if it would carry a transformer to a pole. I was thinking in inverse kinetics (don't know if that's the name in english) to make it.

This means:

dθ= J^-1 * dh

Where dθ is the matrix of the angle vriations, J is the jacobian matrix and dh is the variation of height.

I'll try to ilustrate the problem:

... ______(l2)_____
....\.......................|
......\ ....................| h
.(l1)..\...................|
..........\.................|
--------------------------------
..................d

l1 is the first apendice with 9.2cm and the angle between it and the horizontal line is α, which starts as 30°.
l2 is the second apendice with 9.7cm and the angle between it and the horizontal line is β which starts as 0º.
h is the height of the tip of the arm and starts as 6cm and goes until 15cm.
d is the distance between the robot base and it's tip and is constant at 5cm.

Correct me if i'm wrong but wouldn't the jacobian matrix J be:

l1*cos(α) l2*cos(β)

l2*sin(α) -l1*sin(β) ?