JointSpringForceField Problems

Hi there,

I have recently been using the jointspringforcefield to represent a ball-joint style constraint with rigid bodies, that has angular stiffness and damping. I would like minimal translation movement between joined points (if possible none). An example is where I have set KS_T (translational stiffness) to 1e+10, and KS_R (rotational stiffness) to 5000, I find that with increased value of KS_T that the overall system appears damped, almost as if the translational stiffness is interfering with the rotation stiffness and damping. If the provided scene file has the values of KS_T varied the change in behavior is apparent.
Am I mistaken on how to model this, or is there a different approach?
Also I see the documentation states that KD is damping coefficient, is this for rotational or translational? As no more detail is provided.

Thank you for your help!

<?xml version="1.0" ?>
<Node name="root" gravity="0 -9.81 0" dt="0.01" time="0">
    <RequiredPlugin name="SofaOpenglVisual"/>
    <RequiredPlugin name="SofaPython" pluginName="SofaPython" />
    <Gravity name="G" gravity="0.1 0 0" />       
    <VisualStyle displayFlags="showBehaviorModels showCollisionModels showForceFields" />
    <VisualStyle displayFlags="hideVisual showBehaviorModels showForceFields showCollisionModels showMechanicalMappings" />
    <BruteForceDetection name="default40" />
    <DefaultContactManager name="default41" response="default" />
    <DefaultPipeline name="default42" />
    <MinProximityIntersection name="default43" alarmDistance="1" contactDistance="0.5"/>
    <EulerImplicitSolver name="cg_odesolver" printLog="0"  rayleighStiffness="0.1" rayleighMass="0.1" />
    <CGLinearSolver template="GraphScattered" name="linear solver" iterations="25" tolerance="1e-009" threshold="1e-009" />
    <Node name="default44" gravity="0 -9.81 0">
	<PythonScriptController filename="keyboardControl.py" classname="KeyboardControl"/>        
        <MechanicalObject template="Rigid3d" name="DOFs" position="0 0 0 0 0 0 1 1 0 0 0 0 0 1 3 0 0 0 0 0 1 5 0 0 0 0 0 1 7 0 0 0 0 0 1" velocity="0 0 0 0 0 0" force="0 0 0 0 0 0" externalForce="0 0 0 0 0 0" derivX="0 0 0 0 0 0" restScale="1" />
	<FixedConstraint template="Rigid3d" name="fixOrigin" indices="0" />
        <UniformMass template="Rigid3d" name="mass" totalMass="1" />
        <Node name="default45" gravity="0 -9.81 0">
            <MechanicalObject template="Rigid3d" name="attaches" position="0 0 0 0.707914 0 0 0.707914 -1 0 0 0.707914 0 0 0.707914 1 0 0 0.707914 0 0 0.707914 -1 0 0 0.707914 0 0 0.707914 1 0 0 0.707914 0 0 0.707914 -1 0 0 0.707914 0 0 0.707914 1 0 0 0.707914 0 0 0.707914 -1 0 0 0.707914 0 0 0.707914 1 0 0 0.707914 0 0 0.707914" velocity="0 0 0 0 0 0" force="0 0 0 0 0 0" externalForce="0 0 0 0 0 0" derivX="0 0 0 0 0 0" restScale="1" />
	    <FixedConstraint template="Rigid3d" name="fixOrigin" indices="0" />
            <RigidRigidMapping template="Rigid,Rigid" name="default46" input="@.." output="@." repartition="1 2 2 2 2" />
          

	    <JointSpringForceField template="Rigid3d" name="joint springs" spring="BEGIN_SPRING  0 1  FREE_AXIS 0 0 0 1 1 1  KS_T 1e+3 1e+3  KS_R 500 500  KD 50  R_LIM_X -0.8 0.8  R_LIM_Y -1.57 1.57  R_LIM_Z -2 2  END_SPRING
 BEGIN_SPRING  2 3  FREE_AXIS 0 0 0 1 1 1  KS_T 1e+3 1e+3  KS_R 500 500  KD 50  R_LIM_X -0.8 0.8  R_LIM_Y -1.57 1.57  R_LIM_Z -2 2  END_SPRING
 BEGIN_SPRING  4 5  FREE_AXIS 0 0 0 1 1 1  KS_T 1e+3 1e+3  KS_R 500 500  KD 50  R_LIM_X -0.8 0.8  R_LIM_Y -1.57 1.57  R_LIM_Z -2 2  END_SPRING
 BEGIN_SPRING  6 7  FREE_AXIS 0 0 0 1 1 1  KS_T 1e+3 1e+3  KS_R 500 500  KD 50  R_LIM_X -0.8 0.8  R_LIM_Y -1.57 1.57  R_LIM_Z -2 2  END_SPRING
" />
        </Node>

	<SphereCollisionModel template="Rigid3d" name="Cubes For Collision Cube1" radius="0.2" />
        
    </Node>
</Node>