[ODE] Question about joint

[GLANDIERES, Céline]

Hi,
In fact , in my case I set the body position and the anchor and the axis of
joints, then to move my bodys (for example to rotate them around the hinge
axis), I use the methods dJointSetHingeParam (hinge, dParamVel, velValue)
and  dJointSetHinge2Param (hinge, dParamFMax, ForceValue). You can also use
dBodyAddForce to move your bodys.
Indeed, If you move your body by using dBodySetRotation or bBodySetPosition,
I think (but I'm not sure) that you have to reset the new anchor and axis of
your joint. 

Céline


-----Message d'origine-----
De : Tor ... [mailto:aramboy at kittymail.com] 
Envoyé : mardi 6 mars 2007 07:51
À : ode at ode.org; cglandieres at sogitec.fr
Objet : RE: [ODE] Question about joint

Hi, 

Thanks for your help, maybe I misunderstand something because I'm confusing
about the anchor and axis of the hinge as follow :

1. If I initial object by attach 2 bodies  with hinge at (0, 0, 1), then I
set its position to new coordinate such as

(5, 5, Z) by using dBodySetPosition. Do I need to reset new anchor to the
(5, 5, 1) ? 

2. If I initial object by set the axis of hinge as
dJointSetHingeAxis(joint_hinge, 0, 1, 0) then I rotate the bodies around
Z-Axis by using dBodySetRotation. Do I need to set the new axis for hinge ?


Are there anyway to move and rotate bodies attach by joint without the need
to set new anchor and axis of hinge ?

Thanks again in advance.


PS. I donn't know how to reply thread ODE mailing list. If this message has
any mistake sorry for that.

Tor ...
> ----- Original Message -----
> From: GLANDIERES, Céline <cglandieres at sogitec.fr>
> To: "Tor ..." <aramboy at kittymail.com>, ode at ode.org
> Subject: RE: [ODE] Question about joint
> Date: Mon, 5 Mar 2007 14:26:04 +0100
> 
> 
>   Hi,
> 
> I have the same pb at the beginning, I decreased the mass body (set to 
> 0.05) to decreased the effect of inertia and now my system is stable. 
> For information, I set the others paramters to ERP = 0.1 and CFM = 
> 10-6.
> If it doesn't work you perhaps the center or the axis of your hinge 
> joint are wrong.
> 
> Céline
> 
> -----Message d'origine-----
> De : Tor ... [mailto:aramboy at kittymail.com] Envoyé : dimanche 4 mars 
> 2007 03:54 À : ode at ode.org Objet : [ODE] Question about joint
> 
> Hi, this is the first post for me. If there is any mistake, sorry for
that.
> 
> I have searched for my problem and saw that someone already post it 
> but there are no answer.
> 
> 
> I'm using ode in legged robot simulator.
> I use hinge joint to build robot's leg but I have faced these problem
> 
> 1. bodies that attached by joint are oscillate (slip) although I'm not 
> apply any force or any movement. I think it's joint error problem, so 
> I set ERP to 0.8 or 1.0 and CFM to 0.0 but it's still not stable. How 
> can I solve this problem.
> 
> 2. I construct the robot legs(which composed of many body for each) at 
> the center coordinate. How can I move them to the desired position 
> because I use the same function to construct 2 legs and have to set it 
> in different position.
> 
> Thanks in advance.
> 
> 
> --
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