[ODE] adhesive strength of Hingejoint

[Peter Kyme]

The approach of setting the desired velocity to zero and and infinite 
maximum force will not produce a perfectly stiff joint because of 
inherent limitations (the joint will always slip when under constant force).

The solution I ended up utilising (for a ball joint with attached motor) 
was to wrap the joint with logic such that it would flip between being a 
fixed joint and ball + motor joint depending on the forces it was 
experiencing.

- Pete

Patrick Oppermann wrote:
> 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
> Patrick
> 
> --------------------------------------------------------------------
> 
> Hi Patrick,
> 
> Setting dParamFMax to a high value and dParamVel to 0 would hold the  
> joint.
> 
> cheers
> 
> Hampa
> Toribash.com
> 
> ---------------------------------------------------------------------
> 26 feb 2006 kl. 21.20 skrev Patrick Oppermann at gmx.de:
> 
> Hi!
> I am  working on a virtual assembly arm (with the jMonkeyEngine and
> jmePhysics), which basically consists of boxes connected by
> JointHinge objects.
> 
> 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
> torque.
> 
> 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?
> 
> greetings
> Patrick
> _______________________________________________
> ODE mailing list
> ODE at q12.org
> http://q12.org/mailman/listinfo/ode
> 
> 
> _______________________________________________
> ODE mailing list
> ODE at q12.org
> http://q12.org/mailman/listinfo/ode
>