[ODE] ODE & Motion Sensors & Haptics??

api2551 at cacs.louisiana.edu api2551 at cacs.louisiana.edu
Sun Nov 23 12:01:41 MST 2003

Hi Manohar,
       I am working on a similar thing using a 6 Dof Haptic glove. Any way
coming to your spring damper system, i feel there is a mistake in the way
you are applying the damping force. Try this one out
          F_Drag = K_Spring * (Cursor_Pos - Body_Pos)-K_Damp * BodyVel;
          and then calculate BodyVel for the next time step
           BodyVel += (F_Drag/m)*timestep;
          timestep is the update time you are using
I hope that solves the problem. 


Original Message:
From: Manohar B.S sciphilog at yahoo.com
Date: Sun, 23 Nov 2003 03:18:26 -0800 (PST)
To: ode at q12.org
Subject: [ODE] ODE & Motion Sensors & Haptics??

    Thanks To Nate W & Arun for the reply. (others
refer to ealier mails)

I am doing exactly that way. I am not getting huge
vibrations though, but when the position of the body
being dragged and the cursor point comes very close
then I have the problem high freqency & low amplitude

Ok, I'll reveal more on what I am doing: I am having a
3DoF force feed back device and 1Dof force feedback
device which I myself fabricated (working fine).

as discussed ealier

 F_Drag = K_Spring * (Cursor_Pos - Body_Pos);
 F_Drag += K_Damp * (Cursor_Vel - BodyVel);

 Body_Force = F_Drag;

 Setting drag force on the body using spring damper is
ok, cool. The computed force, say F_Drag, is then
applied to the force feedback device like this

F_ForceFeedback_To_ExternaDevice = -F_Drag;
 Note that when this force is applied to the force
feedback device the Cursor_pos changes because they
are rigidly coupled. Hence, this forms a close loop
system, and unstability is NEVER accepted.

 Due to the spring & mass system, I feel damping when
I change the cursor position with my hand, which is
also not accepted.

Thanks & Regards,
Manohar B.S
Centre For AI & Robotics
Bangalore, INDIA.

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