diff --git a/freecad_to_gazebo/LICENSE b/freecad_to_gazebo/LICENSE
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+++ b/freecad_to_gazebo/LICENSE
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+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
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+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.
diff --git a/freecad_to_gazebo/README.md b/freecad_to_gazebo/README.md
new file mode 100644
index 0000000..b1c4f14
--- /dev/null
+++ b/freecad_to_gazebo/README.md
@@ -0,0 +1,58 @@
+# Freecad to Gazebo exporter
+
+## Introduction
+Freecad to gazebo exporter is a tool for exporting freecad assembly project to gazebo/ros model.
+
+## Design Rules
+This project is in its early stage therefore specific design rules must be followed to work with it.
+* The assmbly file must be created with `A2Plus` (freecad's prefered assembly workspace).
+* Parts of the assembly must be in separate files.
+* Imovable parts of the main assembly must be made in separate subasssemblies.
+* Joints should be represented by AxisConsident constraints with lock rotation turned off.
+* For URDF files to work properly, tree structure must be maintained (ie. parent and childs of constraints must follow tree structure).
+
+## Requirements
+* [Freecad][freecad] with [A2Plus][a2plus] workspace installed
+
+## Usage
+
+#### To generate SDF and URDF model from freecad assembly use python call:
+```python
+freecad_exporter.export_gazebo_model(freecad_assembly_file, model_destination_folder, config)
+```
+Note: Only links and joints are generated in the SDF model. To use the model with ros, use the URDF model.
+
+## Config specification
+```json
+{
+    "name": "robot_name",
+    "joints_limits": {"upper": 90, "lower": -90, "effort": 10, "velocity": 5},
+    "transmission": {
+        "type": "transmission_interface/SimpleTransmission",
+        "hardware_interface": "hardware_interface/PositionJointInterface"
+    },
+    "joints_config": {
+        "type": "position_controllers/JointGroupPositionController",
+        "grouped": true
+    },
+    "joints_pid": {"p": 20.0, "i": 10.0, "d": 0.0, "i_clamp": 0.0},
+    "root_link": "base_link",
+    "ros_package": "humanoid_17dof_description",
+    "sdf_only": false,
+    "export": true
+}
+```
+
+**sdf_only**: Export only SDF.
+
+**export**: Export mesh files.
+
+
+## Future plans
+* Extend collada exporter to export materials from assemblies.
+* Create a FreeCAD workbench to interactively assign joints and export to gazebo.
+* Reduce set of design rules by making it more robust and general purpose.
+* Support any valid structures of assemblies.
+
+[freecad]:https://freecadweb.org
+[a2plus]:https://github.com/kbwbe/A2plus
diff --git a/freecad_to_gazebo/__init__.py b/freecad_to_gazebo/__init__.py
new file mode 100644
index 0000000..4cf8a65
--- /dev/null
+++ b/freecad_to_gazebo/__init__.py
@@ -0,0 +1,28 @@
+import os, platform
+import distro
+
+FREECAD_PATH = ''
+
+# check os types to search for freecad libraries
+if 'linux' in platform.system().lower():
+    dist = distro.linux_distribution(full_distribution_name=False)[0].lower()
+    # TODO: check freecad libs on different distros
+    if dist in ['ubuntu', 'debian', 'fedora', 'arch']:
+        FREECAD_PATH = '/usr/lib/freecad'
+    else:
+        # fallback to default path
+        FREECAD_PATH = '/usr/lib/freecad'
+    print(dist, FREECAD_PATH)
+elif 'nt' in platform.dist().lower():
+    pass
+    # TODO: Find freecad libs on windows
+else:
+    raise Exception("Platform not supported")
+
+# Extend sys.path to include freecad python libraries (including workbenches)
+os.sys.path.extend(os.path.join(FREECAD_PATH, d) for d in os.listdir(FREECAD_PATH))
+
+from freecad_to_gazebo.mesh_exporter import export
+from freecad_to_gazebo.model import *
+from freecad_to_gazebo.freecad_exporter import *
+
diff --git a/freecad_to_gazebo/conversions.py b/freecad_to_gazebo/conversions.py
new file mode 100644
index 0000000..60f151c
--- /dev/null
+++ b/freecad_to_gazebo/conversions.py
@@ -0,0 +1,11 @@
+from math import radians as _radians
+
+
+def deg2rad(d):
+    '''Converts degrees to radians'''
+    return _radians(d)
+
+def flt2str(f):
+    '''Converts floats to formatted string'''
+    return '{:.6f}'.format(f)
+
diff --git a/freecad_to_gazebo/freecad_exporter.py b/freecad_to_gazebo/freecad_exporter.py
new file mode 100644
index 0000000..74e2ab6
--- /dev/null
+++ b/freecad_to_gazebo/freecad_exporter.py
@@ -0,0 +1,200 @@
+import FreeCAD
+from xml.etree import ElementTree as ET
+from xml.dom.minidom import parseString
+import yaml
+from freecad_to_gazebo.model import *
+from freecad_to_gazebo.mesh_exporter import *
+import a2plib
+import argparse
+
+
+def export_gazebo_model(assembly_file, model_dir, configs={}):
+    doc = FreeCAD.open(assembly_file)
+
+    robot_name = configs.get('name', doc.Label)
+    scale = configs.get('scale', 0.001)
+    scale_vec = FreeCAD.Vector([scale]*3)
+    density = configs.get('density', 1000)
+
+    export_mesh = configs.get('export', True)
+
+    assembly_dir = os.path.split(doc.FileName)[0]
+
+    bounding_box = FreeCAD.BoundBox()
+    for obj in doc.findObjects('Part::Feature'):
+        bounding_box.add(obj.Shape.BoundBox)
+
+    bounding_box.scale(*scale_vec)
+
+    global_pose_base = FreeCAD.Vector(bounding_box.XLength/2,
+                                 bounding_box.YLength/2,
+                                 bounding_box.ZLength/2)
+    global_pose_base -= bounding_box.Center
+    global_pose = FreeCAD.Placement()
+    global_pose.Base = global_pose_base
+
+    model = Model(name=robot_name, pose=global_pose)
+    model.self_collide = configs.get('self_collide', False)
+    model.sdf_version = '1.5'
+
+    joint_limits = configs.get('joints_limits', {})
+    joint_dynamics = configs.get('joints_dynamics', {})
+
+    constraints = []
+    for obj in doc.Objects:
+        if a2plib.isA2pPart(obj):
+            name = obj.Label
+            shape = obj.Shape
+            mass = shape.Mass * scale**3 * density
+            com = shape.CenterOfMass * scale
+            inr = shape.MatrixOfInertia
+            inr.scale(*scale_vec*(scale**4) * density)
+            placement = shape.Placement
+            placement.Base.scale(*scale_vec)
+
+            part_file = os.path.join(assembly_dir, obj.sourceFile)
+            part_file = os.path.normpath(part_file)
+            mesh_file = os.path.join(model_dir,
+                                     'meshes',
+                                     os.path.relpath(part_file, assembly_dir))
+            mesh_file = os.path.splitext(mesh_file)[0] + '.dae'
+            mesh_dir = os.path.split(mesh_file)[0]
+
+            if export_mesh:
+                os.makedirs(mesh_dir, exist_ok=True)
+                export(doc, [obj], mesh_file, scale=scale, offset=com*-1)
+
+            pose = placement.copy()
+            pose.Base = com
+
+            pose_rpy = pose.copy()
+            pose_rpy.Base=(np.zeros(3))
+
+
+            inertia = Inertia(inertia=np.array(inr.A)[[0,1,2,5,6,10]])
+            inertial = Inertial(pose=pose_rpy,
+                                mass=mass,
+                                inertia=inertia)
+
+            package = configs.get('ros_package', robot_name)
+            mesh_uri = os.path.join(package,
+                                    os.path.relpath(mesh_file, model_dir))
+            mesh_uri = os.path.normpath(mesh_uri)
+
+            visual = Visual(name=name+'_visual',
+                            mesh=mesh_uri)
+            collision = Collision(name=name+'_collision',
+                                  mesh=mesh_uri)
+
+            link = Link(name=name,
+                        pose=pose,
+                        inertial=inertial,
+                        visual=visual,
+                        collision=collision)
+            model.links.append(link)
+
+        elif a2plib.isA2pConstraint(obj):
+            parent = doc.getObject(obj.Object1)
+            child = doc.getObject(obj.Object2)
+
+            if sorted([parent.Label, child.Label]) in constraints:
+                continue
+
+            if obj.Type == 'axial' and not obj.lockRotation:
+                pose = a2plib.getPos(parent, obj.SubElement1)
+                pose = pose - child.Shape.CenterOfMass
+                pose.scale(*scale_vec)
+
+                joint_pose = FreeCAD.Placement()
+                joint_pose.Base = pose
+                axis_pose = a2plib.getAxis(parent, obj.SubElement1)
+
+                axis = Axis(pose=axis_pose,
+                            lower_limit=joint_limits.get('lower', -90),
+                            upper_limit=joint_limits.get('upper', 90),
+                            effort_limit=joint_limits.get('effort', 10),
+                            velocity_limit=joint_limits.get('velocity', 10),
+                            friction=joint_dynamics.get('friction', 0),
+                            damping=joint_dynamics.get('damping', 0))
+
+                joint = Joint(name=parent.Label+'_'+child.Label,
+                              pose=joint_pose,
+                              parent=parent.Label,
+                              child=child.Label,
+                              type='revolute',
+                              axis=axis)
+
+                model.joints.append(joint)
+
+                constraints.append(sorted([parent.Label, child.Label]))
+
+    os.makedirs(os.path.join(model_dir, 'models'), exist_ok=True)
+
+    with open(os.path.join(model_dir, 'models', robot_name+'.sdf'), 'w') as sdf_file:
+        sdf_file.write(model.to_xml_string('sdf'))
+
+    if not configs.get('sdf_only', None):
+        with open(os.path.join(model_dir, 'models', robot_name+'.urdf'), 'w') as urdf_file:
+            urdf_file.write(model.to_xml_string('urdf'))
+
+        actuators = ET.Element('robot', name=robot_name)
+        gazebo = ET.SubElement(actuators, 'gazebo')
+        plugin = ET.SubElement(gazebo, 'plugin')
+        plugin.set('filename', 'libgazebo_ros_control.so')
+        plugin.set('name', 'gazebo_ros_control')
+        namespace = ET.SubElement(plugin, 'robotNamespace')
+        namespace.text = '/'+robot_name
+        simtype = ET.SubElement(plugin, 'robotSimType')
+        simtype.text = 'gazebo_ros_control/DefaultRobotHWSim'
+
+        tr_configs = configs.get('transmission', {})
+        jt_configs = configs.get('joints_config')
+        pid = configs.get('joints_pid')
+
+        joint_names = [joint.name for joint in model.joints]
+
+        for joint in joint_names:
+            transmission = ET.SubElement(actuators, 'transmission', name=joint)
+            tr_type = ET.SubElement(transmission, 'type')
+            tr_type.text = tr_configs.get('type', 'transmission_interface/SimpleTransmission')
+            actuator = ET.SubElement(transmission, 'actuator', name=joint)
+            hw_interface = ET.SubElement(actuator, 'hardwareInterface')
+            hw_interface.text = tr_configs.get('hardware_interface', 'hardware_interface/PositionJointInterface')
+            reduction = ET.SubElement(actuator, 'mechanicalReduction')
+            reduction.text = '1'
+
+            tr_joint = ET.SubElement(transmission, 'joint', name=joint)
+            hw_interface = ET.SubElement(tr_joint, 'hardwareInterface')
+            hw_interface.text = tr_configs.get('hardware_interface', 'hardware_interface/PositionJointInterface')
+
+        with open(os.path.join(model_dir, 'models', robot_name+'_actuators.urdf'), 'w') as actuators_file:
+            actuators_file.write(parseString(ET.tostring(actuators)).toprettyxml(indent=' '*2))
+
+        control_configs={}
+        control_configs[robot_name] = {
+            'joint_state_controller':{
+                'type': 'joint_state_controller/JointStateController',
+                'publish_rate': 50,
+            }
+        }
+
+        if jt_configs.get('groupped', False):
+            for joint in joint_names:
+                control_configs[robot_name][joint+'_controller'] = {
+                    'type': jt_configs.get('type', 'position_controllers/JointGroupPositionController'),
+                    'joint': joint,
+                    'pid': pid.copy()
+                }
+        else:
+            control_configs[robot_name]['joints_controller'] = {
+                'type': jt_configs.get('type', 'position_controllers/JointGroupPositionController'),
+                'publish_rate': 50,
+                'joints': joint_names
+            }
+            control_configs[robot_name]['gazebo_ros_control/pid_gains'] = {}
+            for joint in joint_names:
+                control_configs[robot_name]['gazebo_ros_control/pid_gains'][joint] = pid.copy()
+        os.makedirs(os.path.join(model_dir, 'config'), exist_ok=True)
+        with open(os.path.join(model_dir, 'config', robot_name+'_controll.yaml'), 'w') as control_configs_file:
+            yaml.dump_all([control_configs], control_configs_file, sort_keys=False)
+
diff --git a/freecad_to_gazebo/mesh_exporter.py b/freecad_to_gazebo/mesh_exporter.py
new file mode 100644
index 0000000..4bb6990
--- /dev/null
+++ b/freecad_to_gazebo/mesh_exporter.py
@@ -0,0 +1,90 @@
+import FreeCAD, Mesh, os, numpy as np
+import collada
+
+
+def export(doc, exportList, filename, scale=1, quality=1, offset=np.zeros(3)):
+    '''FreeCAD collada exporter
+    scale - scaling factor for the mesh
+    quality - mesh tessellation quality
+    offset - offset of the origin of the resulting mesh'''
+
+    colmesh = collada.Collada()
+    colmesh.assetInfo.upaxis = collada.asset.UP_AXIS.Z_UP
+    objind = 0
+    scenenodes = []
+
+    for obj in exportList:
+        bHandled = False
+        if obj.isDerivedFrom("Part::Feature"):
+            bHandled = True
+            m = obj.Shape.tessellate(quality)
+            vindex = []
+            nindex = []
+            findex = []
+            # vertex indices
+            for v in m[0]:
+                vindex.extend([a*scale+b for a, b in zip(v, offset)])
+            # normals
+            for f in obj.Shape.Faces:
+                n = f.normalAt(0,0)
+                for i in range(len(f.tessellate(quality)[1])):
+                    nindex.extend([n.x,n.y,n.z])
+            # face indices
+            for i in range(len(m[1])):
+                f = m[1][i]
+                findex.extend([f[0],i,f[1],i,f[2],i])
+        elif obj.isDerivedFrom("Mesh::Feature"):
+            bHandled = True
+            print("exporting mesh ",obj.Name, obj.Mesh)
+            m = obj.Mesh
+            vindex = []
+            nindex = []
+            findex = []
+            # vertex indices
+            for v in m.Topology[0]:
+                vindex.extend([a*scale+b for a, b in zip(v, offset)])
+            # normals
+            for f in m.Facets:
+                n = f.Normal
+                nindex.extend([n.x,n.y,n.z])
+            # face indices
+            for i in range(len(m.Topology[1])):
+                f = m.Topology[1][i]
+                findex.extend([f[0],i,f[1],i,f[2],i])
+
+        if bHandled:
+            vert_src = collada.source.FloatSource("cubeverts-array"+str(objind),
+                                                  np.array(vindex),
+                                                  ('X', 'Y', 'Z'))
+            normal_src = collada.source.FloatSource("cubenormals-array"+str(objind),
+                                                    np.array(nindex),
+                                                    ('X', 'Y', 'Z'))
+            geom = collada.geometry.Geometry(colmesh,
+                                             "geometry"+str(objind),
+                                             obj.Label,
+                                             [vert_src, normal_src])
+
+            input_list = collada.source.InputList()
+            input_list.addInput(0, 'VERTEX', "#cubeverts-array"+str(objind))
+            input_list.addInput(1, 'NORMAL', "#cubenormals-array"+str(objind))
+            triset = geom.createTriangleSet(np.array(findex),
+                                            input_list,
+                                            "materialref")
+            geom.primitives.append(triset)
+            colmesh.geometries.append(geom)
+
+            geomnode = collada.scene.GeometryNode(geom)
+            node = collada.scene.Node("node"+str(objind), children=[geomnode])
+
+            #TODO: Add materials handling
+            scenenodes.append(node)
+
+        objind += 1
+
+    scene = collada.scene.Scene("scene", scenenodes)
+    colmesh.scenes.append(scene)
+    colmesh.scene = scene
+
+    colmesh.write(filename)
+    print("file %s successfully created\n" % filename)
+
diff --git a/freecad_to_gazebo/model.py b/freecad_to_gazebo/model.py
new file mode 100644
index 0000000..c7072a3
--- /dev/null
+++ b/freecad_to_gazebo/model.py
@@ -0,0 +1,377 @@
+from freecad_to_gazebo.conversions import *
+import FreeCAD
+from xml.etree import ElementTree as ET
+from xml.dom.minidom import parseString
+
+
+def add_poses(p1, p2):
+    return FreeCAD.Placement(p1.toMatrix() + p2.toMatrix())
+
+def subtract_poses(p1, p2):
+    return FreeCAD.Placement(p1.toMatrix() + p2.toMatrix().inverse())
+
+def pose_to_xml(pose, fmt='sdf'):
+    '''Converts a pose/freecad placement/ to xml element
+    with tag "pose" for sdf and "origin" for urdf'''
+    xyz = pose.Base
+    rpy = pose.Rotation.toEuler()
+
+    if fmt == 'urdf':
+        args = {'xyz': ' '.join([flt2str(i) for i in xyz]),
+                'rpy': ' '.join([flt2str(deg2rad(j)) for j in rpy])}
+        return ET.Element('origin', args)
+
+    pose_elem = ET.Element('pose')
+    pose_elem.text = ' '.join([flt2str(i) for i in xyz]
+                              + [flt2str(deg2rad(j)) for j in rpy])
+
+    return pose_elem
+
+def pose_xyz(pose):
+    '''Returns the xyz/Base portion of a pose as string'''
+    xyz = pose.Base if hasattr(pose, 'Base') else pose
+    return ' '.join([flt2str(i) for i in xyz])
+
+
+class SpatialEntity(object):
+    '''A base class for sdf/urdf elements containing name, pose and urdf_pose'''
+    def __init__(self, **kwargs):
+        self.name = kwargs.get('name', '')
+        self.pose = kwargs.get('pose', FreeCAD.Placement())
+        self.global_pose = kwargs.get('global_pose', FreeCAD.Placement())
+        self.urdf_pose = kwargs.get('urdf_pose', FreeCAD.Placement())
+
+        self.formats = ['sdf', 'urdf']
+
+    def to_xml(self, fmt='sdf'):
+        '''Call this to check if a format is supported or not'''
+        if not fmt in self.formats:
+            raise Exception('Invalid export format')
+
+
+class Model(SpatialEntity):
+    '''A class representing a model/robot'''
+    def __init__(self, **kwargs):
+        super(Model, self).__init__(**kwargs)
+        self.static = kwargs.get('static', False)
+        self.self_collide = kwargs.get('self_collide', False)
+        self.sdf_version = kwargs.get('sdf_version', 1.5)
+
+        self.links = []
+        self.joints = []
+
+        if 'link' in kwargs:
+            self.links.append(kwargs.get('link', Link()))
+        self.links.extend(kwargs.get('links', []))
+
+        if 'joint' in kwargs:
+            self.joints.append(kwargs.get('joint', Joint()))
+        self.joints.extend(kwargs.get('joints', []))
+
+    def get_link(self, link_name):
+        for link in self.links:
+            if link_name == link.name:
+                return link
+
+    def get_joint(self, joint_name):
+        pass
+
+    def get_root_link(self):
+        root_link = None
+        for link in self.links:
+            if not link.parent_joint:
+                root_link = link
+        return root_link
+
+    def build_tree(self):
+        for joint in self.joints:
+            joint.parent_link = self.get_link(joint.parent)
+            if not joint.parent_link:
+                raise Exception('Parent not found for joint %s' % joint.name)
+            joint.parent_link.child_joints.append(joint)
+
+            joint.child_link = self.get_link(joint.child)
+            if not joint.child_link:
+                raise Exception('Child not found for joint %s' % joint.name)
+            joint.child_link.parent_joint = joint
+
+    def calculate_global_poses(self):
+        for link in self.links:
+            link.global_pose = add_poses(self.pose, link.pose)
+        for joint in self.joints:
+            joint.global_pose = add_poses(joint.child_link.global_pose, joint.pose)
+
+    def to_xml(self, fmt='sdf'):
+        '''returns xml element of a model/robot'''
+        super(Model, self).to_xml(fmt)
+
+        self.build_tree()
+        self.calculate_global_poses()
+
+        tag = 'robot' if fmt=='urdf' else 'model'
+        model = ET.Element(tag, name=self.name)
+
+        if fmt == 'sdf':
+            model.append(pose_to_xml(self.pose))
+            static = ET.SubElement(model, 'static')
+            static.text = str(self.static).lower()
+            self_collide = ET.SubElement(model, 'self_collide')
+            self_collide.text = str(self.self_collide).lower()
+        else:
+            model.set('static', str(self.static).lower())
+
+            root_link = self.get_root_link()
+            if not root_link:
+                raise Exception("Couldn't find root link")
+            model.append(ET.Element('link', name=root_link.name+'_root'))
+        for link in self.links:
+            model.append(link.to_xml(fmt))
+
+        if fmt=='urdf':
+            root_joint = ET.Element('joint',
+                                    {"name": root_link.name+'_root',
+                                     "type": "fixed"})
+            root_joint.append(pose_to_xml(root_link.global_pose, fmt))
+            ET.SubElement(root_joint, 'parent', link= root_link.name+'_root')
+            ET.SubElement(root_joint, 'child', link= root_link.name)
+            model.append(root_joint)
+
+        for joint in self.joints:
+            model.append(joint.to_xml(fmt))
+
+        if fmt == 'sdf':
+            sdf = ET.Element('sdf', version=str(self.sdf_version))
+            sdf.append(model)
+            return sdf
+
+        return model
+
+    def to_xml_string(self, fmt='sdf', header=True):
+        dom = parseString(ET.tostring(self.to_xml(fmt)))
+        return dom.toprettyxml(indent=' '*2)
+
+
+class Inertia(object):
+    '''A clss representing an inertia element'''
+    def __init__(self, **kwargs):
+        self.ixx = kwargs.get('ixx', 0)
+        self.ixy = kwargs.get('ixy', 0)
+        self.ixz = kwargs.get('ixz', 0)
+        self.iyy = kwargs.get('iyy', 0)
+        self.iyz = kwargs.get('iyz', 0)
+        self.izz = kwargs.get('izz', 0)
+        if 'inertia' in kwargs:
+            self.ixx, self.ixy, self.ixz = kwargs.get('inertia', [0]*6)[:3]
+            self.iyy, self.iyz, self.izz = kwargs.get('inertia', [0]*6)[3:]
+        self.coords = 'ixx', 'ixy', 'ixz', 'iyy', 'iyz', 'izz'
+
+    def to_xml(self, fmt='sdf'):
+        '''returns inetria xml element'''
+        inertia = ET.Element('inertia')
+        for coord in self.coords:
+            if fmt == 'sdf':
+                elem = ET.SubElement(inertia, coord)
+                elem.text = flt2str(getattr(self, coord, 0))
+            else:
+                inertia.set(coord, flt2str(getattr(self, coord, 0)))
+        return inertia
+
+
+class Inertial(SpatialEntity):
+    '''A class representing an inertial element'''
+    def __init__(self, **kwargs):
+        super(Inertial, self).__init__(**kwargs)
+        self.mass = kwargs.get('mass', 0)
+        self.inertia = kwargs.get('inertia', Inertia())
+
+    def to_xml(self, fmt='sdf'):
+        '''returns inertial xml element'''
+        super(Inertial, self).to_xml(fmt)
+        inertial = ET.Element('inertial')
+        pose = self.pose if fmt=='sdf' else self.urdf_pose
+        inertial.append(pose_to_xml(pose, fmt=fmt))
+        mass = ET.SubElement(inertial, 'mass')
+        if fmt == 'sdf':
+            mass.text = flt2str(self.mass)
+        else:
+            mass.set('value', flt2str(self.mass))
+        inertial.append(self.inertia.to_xml(fmt=fmt))
+
+        return inertial
+
+
+class Geom(SpatialEntity):
+    '''A base class for collision and visual classes'''
+    def __init__(self, **kwargs):
+        super(Geom, self).__init__(**kwargs)
+        self.mesh = kwargs.get('mesh', '')
+        self.type = kwargs.get('type', 'visual')
+
+    def to_xml(self, fmt='sdf'):
+        '''returns visual or collision xml element'''
+        super(Geom, self).to_xml(fmt)
+        elem = ET.Element(self.type, name=self.name)
+        pose = self.pose if fmt=='sdf' else self.urdf_pose
+        elem.append(pose_to_xml(pose, fmt=fmt))
+        geom = ET.SubElement(elem, 'geometry')
+        mesh = ET.SubElement(geom, 'mesh')
+        if fmt=='urdf':
+            mesh.set('filename', 'package://' + self.mesh)
+        else:
+            uri = ET.SubElement(mesh, 'uri')
+            uri.text = 'model://' + self.mesh
+
+        return elem
+
+
+class Visual(Geom):
+    '''A class representing a visual element'''
+    def __init__(self, **kwargs):
+        super(Visual, self).__init__(type='visual', **kwargs)
+
+
+class Collision(Geom):
+    '''A class representing a collision element'''
+    def __init__(self, **kwargs):
+        super(Collision, self).__init__(type='collision', **kwargs)
+
+
+class Link(SpatialEntity):
+    '''A class representing a link element'''
+    def __init__(self, **kwargs):
+        super(Link, self).__init__(**kwargs)
+        self.inertial = kwargs.get('inertial', Inertial())
+        self.visuals = []
+        self.collisions = []
+
+        self.parent_joint = None
+        self.child_joints = []
+
+        if 'visual' in kwargs:
+            self.visuals.append(kwargs.get('visual', Visual()))
+        self.visuals.extend(kwargs.get('visuals', []))
+
+        if 'collision' in kwargs:
+            self.visuals.append(kwargs.get('collision', Collision()))
+        self.collisions.extend(kwargs.get('collisions', []))
+
+    def to_xml(self, fmt='sdf'):
+        '''returns link xml element'''
+        super(Link, self).to_xml(fmt)
+        link = ET.Element('link', name=self.name)
+
+        if self.parent_joint:
+            self.urdf_pose = subtract_poses(self.global_pose,
+                                           self.parent_joint.global_pose)
+        else:
+            self.urdf_pose = FreeCAD.Placement()
+
+        if fmt == 'sdf':
+            link.append(pose_to_xml(self.pose, fmt=fmt))
+
+        self.inertial.urdf_pose = add_poses(self.inertial.pose, self.urdf_pose)
+        link.append(self.inertial.to_xml(fmt=fmt))
+
+        for visual in self.visuals:
+            visual.urdf_pose = self.urdf_pose.copy()
+            link.append(visual.to_xml(fmt=fmt))
+        for collision in self.collisions:
+            collision.urdf_pose = self.urdf_pose.copy()
+            link.append(collision.to_xml(fmt=fmt))
+
+        return link
+
+
+class Axis(SpatialEntity):
+    '''A class representing an axis element'''
+    def __init__(self, **kwargs):
+        super(Axis, self).__init__(**kwargs)
+        self.lower_limit = kwargs.get('lower_limit', 0)
+        self.upper_limit = kwargs.get('upper_limit', 0)
+        self.effort_limit = kwargs.get('effort_limit', 0)
+        self.velocity_limit = kwargs.get('velocity_limit', 0)
+        self.friction = kwargs.get('friction', 0)
+        self.damping = kwargs.get('damping', 0)
+        self.use_parent_frame = kwargs.get('use_parent_frame', False)
+
+    def to_xml(self, fmt='sdf'):
+        '''returns an axis xml element for sdf
+        or an array of axis and limit xml elements for urdf'''
+        super(Axis, self).to_xml(fmt)
+
+        axis = ET.Element('axis')
+        if fmt=='sdf':
+            xyz = ET.SubElement(axis, 'xyz')
+            xyz.text = pose_xyz(self.pose)
+            limit = ET.SubElement(axis, 'limit')
+            lower = ET.SubElement(limit, 'lower')
+            lower.text = flt2str(deg2rad(self.lower_limit))
+            upper = ET.SubElement(limit, 'upper')
+            upper.text = flt2str(deg2rad(self.upper_limit))
+            effort = ET.SubElement(limit, 'effort')
+            effort.text = flt2str(self.effort_limit)
+            velocity = ET.SubElement(limit, 'velocity')
+            velocity.text = flt2str(self.velocity_limit)
+            dynamics = ET.SubElement(axis, 'dynamics')
+            friction = ET.SubElement(dynamics, 'friction')
+            friction.text = flt2str(self.friction)
+            damping = ET.SubElement(dynamics, 'damping')
+            damping.text = flt2str(self.damping)
+            use_parent_frame = ET.SubElement(axis, 'use_parent_model_frame')
+            use_parent_frame.text = str(self.use_parent_frame).lower()
+        else:
+            axis.set('xyz', pose_xyz(self.pose))
+            axis.set('use_parent_model_frame', str(self.use_parent_frame).lower())
+            limit = ET.Element('limit')
+            limit.set('lower', flt2str(deg2rad(self.lower_limit)))
+            limit.set('upper', flt2str(deg2rad(self.upper_limit)))
+            limit.set('effort', flt2str(self.effort_limit))
+            limit.set('velocity', flt2str(self.velocity_limit))
+
+            dynamics = ET.Element('dynamics')
+            dynamics.set('friction', flt2str(self.friction))
+            dynamics.set('damping', flt2str(self.damping))
+
+            return [axis, limit, dynamics]
+        return axis
+
+
+class Joint(SpatialEntity):
+    '''A class representing a joint element'''
+    def __init__(self, **kwargs):
+        super(Joint, self).__init__(**kwargs)
+        self.parent = kwargs.get('parent', '')
+        self.child = kwargs.get('child', '')
+        self.type = kwargs.get('type', '')
+        self.axis = kwargs.get('axis', Axis())
+
+        self.parent_link = None
+        self.child_link = None
+
+    def to_xml(self, fmt='sdf'):
+        '''returns a joint xml element'''
+        super(Joint, self).to_xml(fmt)
+
+        if self.parent_link.parent_joint:
+            self.urdf_pose = subtract_poses(self.global_pose,
+                                            self.parent_link.parent_joint.global_pose)
+        else:
+            self.urdf_pose = subtract_poses(self.global_pose, self.parent_link.global_pose)
+
+        joint = ET.Element('joint', {'name': self.name, 'type': self.type})
+        pose = self.pose if fmt=='sdf' else self.urdf_pose
+        joint.append(pose_to_xml(pose, fmt=fmt))
+
+        parent = ET.SubElement(joint, 'parent')
+        child = ET.SubElement(joint, 'child')
+        if fmt == 'sdf':
+            parent.text = self.parent
+            child.text = self.child
+            joint.append(self.axis.to_xml(fmt=fmt))
+        else:
+            parent.set('link', self.parent)
+            child.set('link', self.child)
+            joint.extend(self.axis.to_xml(fmt=fmt))
+
+        return joint
+