[ODE] adhesive strength of Hingejoint

Erin Catto erincatto at sbcglobal.net
Mon Feb 27 23:55:00 MST 2006

You can apply positional feedback error:

motor_vel = desired_vel + beta / dt * (desired_pos - actual_pos)

beta approx [0.1, 0.3]

If you care about the dynamics, I suggest using a max motor torque close to
real specs.


-----Original Message-----
From: ode-bounces at q12.org [mailto:ode-bounces at q12.org] On Behalf Of Patrick
Sent: Monday, February 27, 2006 8:36 AM
To: ode at q12.org
Subject: [ODE] adhesive strength of Hingejoint

Hm, I tried a value of 1.000.000 and it had no effect at all (the arm
segments have a mass of 100 and 50). dParamFMax specifies the maximum amount
of force that the hinge can apply to its two Bodies. But I need to control
the "stiffness" of the hinge so it doesn't sink down when its velocity is 0.

See the screenshot at http://www.totalhavoc.de/dev/robotArm.JPG


Hi Patrick,

Setting dParamFMax to a high value and dParamVel to 0 would hold the joint.



26 feb 2006 kl. 21.20 skrev Patrick Oppermann at gmx.de:

I am  working on a virtual assembly arm (with the jMonkeyEngine and
jmePhysics), which basically consists of boxes connected by JointHinge

The Problem is that the arm is always sagging down because of its own weight
as soon as it is stopped by setting the hinge's velocity to 0.
Neither reducing the mass solves the problem, nor does increasing the

Is there a way to stabilize the arm when it is not moving? Is there a
specific ode parameter that controls the ,grip', the adhesive strength of
the Joint? I couldn't find any yet.

I tried to stabilize it by setting the Hinge's minAngle and maxAngle stops
to its current rotation angle (plus/minus a little tolerance) when it is
stopped. Unluckily the Joint seems to be reset completely by
dJointSetHingeParam() with the parameter dParamVel. Is that so?

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