Messuring absolute speed of CS in SimMechanics

Hi,

What I'm trying to do: I have build an robotic arm in SimMechanics. The joint where my arm is connected is moving around randomly. Now I want to messure the speed of the tip of the arm (the hand). With this data, i want to move the arm joints, so that the speed of the hand always stays near zero.

How I'm trying to do it: I'am using a Body Sensor that is connected to the "hand"-body of the robotic arm. With this Body Sensor I try to messure the velocity [m/s] and my respect CS is "Absolute (World)". But when i connect a Scope, it only shows 0. Although the connected CS to the Body Sensor is moving around.

What am I doing wrong? How else could I messure the speed of the "hand"? I'm using R2009a.

Thanks in advance, Alex

Answer 1

[Alexander]

Ok, I think I have solved my problem. I messure the absolute position of the hand, then i use the derivative block. With the signals i get, i use the pythagorean theorem.

Answer 2

[Ehsan Asadi]

I am experiencing the same problem, The position curve is not zero but all the velocity and angular velocities are zero!!!! and I do not know why!