Simtrans error

test.urdf

<?xml version="1.0" ?>
<robot name="test">
  <link name="base_link" />

  <link name="test_start">
  </link>

  <joint name="test_start" type="fixed">
    <parent link="base_link" />
    <child link="test_start" />
    <origin rpy="0.0 0.0 0.0" xyz="-0.625 0.0 0.0" />
  </joint>

  <link name="test_goal">
  </link>

  <joint name="test_goal" type="fixed">
    <parent link="base_link" />
    <child link="test_goal" />
    <origin rpy="0.0 0.0 0.0" xyz="0.6000000238418579 0.0 0.25" />
  </joint>

  <link name="test_ramp">
  </link>

  <joint name="test_ramp" type="fixed">
    <parent link="base_link" />
    <child link="test_ramp" />
    <origin rpy="0.0 -0.26 0.0" xyz="0.02 0.0 0.045" />
  </joint>

</robot>

test.wrl

#VRML V2.0 utf8

PROTO Joint [
  exposedField     SFVec3f      center              0 0 0
  exposedField     MFNode       children            []
  exposedField     MFFloat      llimit              []
  exposedField     MFFloat      lvlimit             []
  exposedField     SFRotation   limitOrientation    0 0 1 0
  exposedField     SFString     name                ""
  exposedField     SFRotation   rotation            0 0 1 0
  exposedField     SFVec3f      scale               1 1 1
  exposedField     SFRotation   scaleOrientation    0 0 1 0
  exposedField     MFFloat      stiffness           [ 0 0 0 ]
  exposedField     SFVec3f      translation         0 0 0
  exposedField     MFFloat      ulimit              []
  exposedField     MFFloat      uvlimit             []
  exposedField     SFString     jointType           ""
  exposedField     SFInt32      jointId             -1
  exposedField     SFVec3f      jointAxis           0 0 1

  exposedField     SFFloat      gearRatio           1
  exposedField     SFFloat      rotorInertia        0
  exposedField     SFFloat      rotorResistor       0
  exposedField     SFFloat      torqueConst         1
  exposedField     SFFloat      encoderPulse        1
]
{
  Transform {
    center           IS center
    children         IS children
    rotation         IS rotation
    scale            IS scale
    scaleOrientation IS scaleOrientation
    translation      IS translation
  }
}

PROTO Segment [
  field           SFVec3f     bboxCenter        0 0 0
  field           SFVec3f     bboxSize          -1 -1 -1
  exposedField    SFVec3f     centerOfMass      0 0 0
  exposedField    MFNode      children          [ ]
  exposedField    SFNode      coord             NULL
  exposedField    MFNode      displacers        [ ]
  exposedField    SFFloat     mass              0
  exposedField    MFFloat     momentsOfInertia  [ 0 0 0 0 0 0 0 0 0 ]
  exposedField    SFString    name              ""
  eventIn         MFNode      addChildren
  eventIn         MFNode      removeChildren
]
{
  Group {
    addChildren    IS addChildren
    bboxCenter     IS bboxCenter
    bboxSize       IS bboxSize
    children       IS children
    removeChildren IS removeChildren
  }
}

PROTO Surface [
 field   SFVec3f bboxCenter 0 0 0
 field   SFVec3f bboxSize   -1 -1 -1
 field   MFNode  visual     [ ]
 field   MFNode  collision  [ ]
 eventIn MFNode  addChildren
 eventIn MFNode  removeChildren
]
{
  Group {
    addChildren    IS addChildren
    bboxCenter     IS bboxCenter
    bboxSize       IS bboxSize
    children       IS visual
    removeChildren IS removeChildren
  }
}

PROTO Humanoid [
  field           SFVec3f    bboxCenter            0 0 0
  field           SFVec3f    bboxSize              -1 -1 -1
  exposedField    SFVec3f    center                0 0 0
  exposedField    MFNode     humanoidBody          [ ]
  exposedField    MFString   info                  [ ]
  exposedField    MFNode     joints                [ ]
  exposedField    SFString   name                  ""
  exposedField    SFRotation rotation              0 0 1 0
  exposedField    SFVec3f    scale                 1 1 1
  exposedField    SFRotation scaleOrientation      0 0 1 0
  exposedField    MFNode     segments              [ ]
  exposedField    MFNode     sites                 [ ]
  exposedField    SFVec3f    translation           0 0 0
  exposedField    SFString   version               "1.1"
  exposedField    MFNode     viewpoints            [ ]
]
{
  Transform {
    bboxCenter       IS bboxCenter
    bboxSize         IS bboxSize
    center           IS center
    rotation         IS rotation
    scale            IS scale
    scaleOrientation IS scaleOrientation
    translation      IS translation
    children [
      Group {
        children IS viewpoints
      }
    ]
  }
}

PROTO ExtraJoint [
  exposedField SFString link1Name ""
  exposedField SFString link2Name ""
  exposedField SFVec3f  link1LocalPos 0 0 0
  exposedField SFVec3f  link2LocalPos 0 0 0
  exposedField SFString jointType "xyz"
  exposedField SFVec3f  jointAxis 1 0 0
]
{
}



DEF base_link Humanoid {
  humanoidBody [
    DEF base_link Joint {
      jointType "free"
      translation 0.0 0.0 0.0
      rotation 0 1 0 0
      children [
        DEF base_link Segment {
          mass 0
          centerOfMass 0 0 0
          momentsOfInertia [1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0]
          children [
          ]
        }
            
        DEF test_start Joint {
          jointType "fixed"
          jointId 0
          translation 0.0 0.0 0.0
          rotation 0 1 0 0
          children [
            DEF test_start Segment {
              mass 0.001
              centerOfMass 0 0 0
              momentsOfInertia [1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0]
              children [
              ]
            }
                
          ]
        }
        DEF test_goal Joint {
          jointType "fixed"
          jointId 1
          translation 0.0 0.0 0.0
          rotation 0 1 0 0
          children [
            DEF test_goal Segment {
              mass 0.001
              centerOfMass 0 0 0
              momentsOfInertia [1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0]
              children [
              ]
            }
                
          ]
        }
        DEF test_ramp Joint {
          jointType "fixed"
          jointId 2
          translation 0.0 0.0 0.0
          rotation 0 1 0 0
          children [
            DEF test_ramp Segment {
              mass 0.001
              centerOfMass 0 0 0
              momentsOfInertia [1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0]
              children [
              ]
            }
                
          ]
        }
      ]
    }
  ]
  joints [
    USE test_start,
    USE test_goal,
    USE test_ramp
  ]
  
  name "base_link"
  version "1.0"
}