The AddFixed method creates a work plane at the specified position in space, but it is not grounded. Placing a constraint on the work plane could cause it to move depending on what it is being constrained to and the behavior of the solver. The fact that it is not grounded and still have six degrees of freedom available allows the solver to reposition it as needed.
As a workaround, please set oAssyPlane.Grounded = True before AddMateConstraint and set Grounded back to its original value.
The code below assumes two occurrences in one assembly. The coordinate system of the second occurrence is not aligned with the assembly’s.
Public Sub MateConstraintOfWorkPlanes()
' get the active component definition
Dim oAsmCompDef As AssemblyComponentDefinition
oAsmCompDef = m_inventorApplication. _
ActiveDocument.ComponentDefinition
' get the workplane
Dim oAssyPlane As WorkPlane
Dim OPt As Point = Nothing
Dim XV As UnitVector = Nothing
Dim YV As UnitVector = Nothing
oAsmCompDef.WorkPlanes(2). _
GetPosition(OPt, XV, YV)
' and add fixed
oAssyPlane = oAsmCompDef. _
WorkPlanes.AddFixed(OPt, XV, YV)
' create geometry proxy
Dim oOcc1 As ComponentOccurrence
oOcc1 = oAsmCompDef.Occurrences(2)
Dim oPartPlaneXZ As WorkPlane
oPartPlaneXZ = oOcc1.Definition.WorkPlanes(2)
Dim oPartPlane1 As WorkPlaneProxy = Nothing
oOcc1.CreateGeometryProxy( _
oPartPlaneXZ, oPartPlane1)
' and finally add the constraint
Dim oldV As Boolean
oldV = oAssyPlane.Grounded
oAssyPlane.Grounded = True
oAsmCompDef.Constraints.AddMateConstraint( _
oPartPlane1, oAssyPlane, 0)
oAssyPlane.Grounded = oldV
End Sub
