drakeURDF.xsd

<?xml version="1.0" encoding="UTF-8"?>

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://drake.mit.edu"
    xmlns="http://drake.mit.edu" elementFormDefault="qualified">

    <xs:annotation>
        <xs:documentation>XML Schema for DrakeURDF v1.0

Documents URDF support for Drake, which implements much of the ROS URDF specification, but also adds a number of new elements.
   </xs:documentation>
    </xs:annotation>
    <xs:simpleType name="matlab_parameter_expression">
        <xs:annotation>
            <xs:documentation>Can be any string that will evaluate as a polynomial using "eval" in the matlab environment, where parameters are referenced with $param_name.
Example:

"$m * $l^2"
or
"$m2 * ($lc2 - $l1)"
</xs:documentation>
        </xs:annotation>
        <xs:restriction base="xs:string"/>
    </xs:simpleType>
    <xs:complexType name="parameter">
        <xs:attribute name="name" type="xs:string" use="required"/>
        <xs:attribute name="value" type="xs:double" use="required"/>
        <xs:attribute default="-INF" name="lb" type="xs:double" use="optional">
            <xs:annotation>
                <xs:documentation>lower bound</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute default="INF" name="ub" type="xs:double" use="optional">
            <xs:annotation>
                <xs:documentation>upper bound
</xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>
    <xs:complexType name="loop_joint">
        <xs:annotation>
            <xs:documentation>You can add a loop joint if you have a kinematic loop (e.g. four-bar linkage, or even something more complicated) in your robot.  To use this interface, you must first describe every link in your robot as part of a kinematic tree (no loops). You should be able to take a path through the linkages that touches everything without any loops. Then add the remaining loops by referencing existing links from the tree.

There are a few limitations with the current implementation.  We do not currently support joint limits nor actuators at the new joint created by the loop_joint tag.  For all of the systems we have modeled so far, there has always been at least one of these "simple" joints in each kinematic loop; and we are simply careful to write down the initial kinematic tree so that it includes all of the more complex joints, leaving the simple joint as the loop joint.
</xs:documentation>
        </xs:annotation>
        <xs:all>
            <xs:element name="link1" type="link_reference_w_pose" maxOccurs="1" minOccurs="1">
                <xs:annotation>
                    <xs:documentation>String naming the link on one side of
the joint.</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="link2" type="link_reference_w_pose" maxOccurs="1" minOccurs="1">
                <xs:annotation>
                    <xs:documentation>String naming the link on the other side of
the joint.</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element minOccurs="0" name="axis" type="axis" maxOccurs="1"/>
        </xs:all>
        <xs:attribute name="name" type="xs:string" use="required"/>
        <xs:attribute fixed="continuous" name="type" type="xs:string" use="optional">
            <xs:annotation>
                <xs:documentation>Currently must be ’continuous’. The intent is to
eventually support all of the same types as a 'joint' element. See the joint element documentation.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>
    <xs:complexType name="force_element">
        <xs:choice>
            <xs:element name="linear_spring_damper" type="linear_spring_damper"/>
            <xs:element name="wing" type="wing">
                <xs:annotation>
                    <xs:documentation>Wing element supporting flat plates, airfoils.  See wing_with_control_surface for a wing with a control surface attached.</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="thrust" type="thrust">
                <xs:annotation>
                    <xs:documentation>Thrust elements produce a force on a point on the parent body in a
specified direction. The magnitude of the force is scaled from an input
to the system. Possible applications are the throttle input and force
produced by a propeller on an airplane, or thrusters on the hands and
feet of an Atlas robot to make Iron Man.</xs:documentation>
                </xs:annotation>
            </xs:element>

            <xs:element name="propellor" type="propellor">
                <xs:annotation>
                    <xs:documentation>Propellor elements produce both a thrust at a point on the parent body in a
specified direction, along with a moment whose axis is the same as the thrust axis. This is useful for modelling propellors,
which typically produce both a thrust and a moment due to aerodynamic drag. The magnitude of the force and torque are scaled
from an input to the system, with different scalings for each.</xs:documentation>
                </xs:annotation>
            </xs:element>

            <xs:element name="bluff_body" type="bluff_body">
                <xs:annotation>
                    <xs:documentation>A bluff body that provides only drag force in xyz.</xs:documentation>
                </xs:annotation>
            </xs:element>



            <xs:element name="added_mass" type="added_mass">
                <xs:annotation>
                    <xs:documentation> Places added-mass coefficients on a point on the parent body. Added-mass forces act like a 'drag' that is proportional to the acceleration of the body, rather than the velocity. Important when the body is comparable in mass to the surrounding fluid, or if rapid motions are needed.

These forces are represented by a 6x6 matrix 'Ma' similar to a mass matrix, where the force is F=-Ma*a (+coriolis terms). Each matrix element is refered as 'mij', where 'i' and 'j' are the rows and columns of the matrix. As is standard in the oceanographic literature, rows 123 are the linear accelerations, and 456 are the angular accelerations [note this is opposite of Featherstone's notation] </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="buoyancy" type="buoyancy">
                <xs:annotation>
                    <xs:documentation> Adds a buoyancy force to the parent body, placed at a defined center of buoyancy. </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="torsional_spring" type="torsional_spring"/>
        </xs:choice>
        <xs:attribute name="name" type="xs:string"/>
    </xs:complexType>
    <xs:complexType name="pose">
        <xs:attribute name="xyz" type="xs:string" default="0 0 0">
            <xs:annotation>
                <xs:documentation>Represents the Cartesian offset</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="rpy" type="xs:string" default="0 0 0">
            <xs:annotation>
                <xs:documentation>Represents the fixed-axis (aka extrinsic) roll, pitch and yaw angles in radians. </xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>
    <xs:complexType name="linear_spring_damper">
        <xs:all>
            <xs:element name="link1" type="link_reference_w_pose">
                <xs:annotation>
                    <xs:documentation>String naming the link on one side
of the spring/damper with an (optional) pose specified relative to the coordinate system on the link</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="link2" type="link_reference_w_pose">
                <xs:annotation>
                    <xs:documentation>String naming the link on the other side
of the spring/damper with an (optional) pose specified relative to the coordinate system on the link</xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:all>
        <xs:attribute default="0" name="rest_length" type="xs:double"/>
        <xs:attribute default="0" name="stiffness" type="xs:double">
            <xs:annotation>
                <xs:documentation>in Newtons per meter
</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute default="0" name="damping" type="xs:double">
            <xs:annotation>
                <xs:documentation>in Newton seconds per meter.  positive values resist motion.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="torsional_spring">
        <xs:annotation>
            <xs:documentation>currently only supported for continuous and rotational joints.  </xs:documentation>
        </xs:annotation>
        <xs:all>
            <xs:element name="joint" type="joint_reference">
                <xs:annotation>
                    <xs:documentation>String naming the joint of the spring/damper</xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:all>
        <xs:attribute default="0" name="rest_angle" type="xs:double">
            <xs:annotation>
                <xs:documentation>in radians</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute default="0" name="stiffness" type="xs:double">
            <xs:annotation>
                <xs:documentation>in Newton-meters per radian
</xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="wing">
        <xs:all>
            <xs:element name="parent" type="link_reference">
                <xs:annotation>
                    <xs:documentation>String naming the link on which
this wing is attached.</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="origin" type="pose" minOccurs="0">
                <xs:annotation>
                    <xs:documentation>This defines the position of
the quarter-chord point of the airfoil, since that is the reference point
used for the moment coefficient. RPY support has been excluded, requiring
the axes of the airfoil to line up with those of its parent body.</xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:all>
        <xs:attribute name="profile" type="xs:string">
            <xs:annotation>
                <xs:documentation>one of the following
strings:
· The path to a .mat file that can be loaded and contains the three
variables ”CLSpline, CDSpline, CMSpline”
· The string, ’flat plate’
39
· File location of a .dat file generated by Xfoil
· A NACA airfoil designation: ’NACA0012’</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="chord" type="xs:double">
            <xs:annotation>
                <xs:documentation>the chord length in
meters.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="span" type="xs:double">
            <xs:annotation>
                <xs:documentation>the span of the wing
in meters.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="stall_angle" type="xs:double">
            <xs:annotation>
                <xs:documentation>the angle
in degrees upon which the lift and drag performance returns to that of
a flat plate. (this value is ignored if the profile is set to a flat plate).</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="nominal_speed" type="xs:double">
            <xs:annotation>
                <xs:documentation>an approximate
nominal speed in meters per second used to calculate the
Reynolds number around which we design the aerodynamic coefficients.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="visual_geometry" type="xs:boolean" default="true">
            <xs:annotation>
                <xs:documentation>enable or disable automatic drawing of the wing</xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="wing_with_control_surface">
        <xs:all>
            <xs:element name="parent" type="link_reference">
                <xs:annotation>
                    <xs:documentation>String naming the link on which
this wing is attached.</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="origin" type="pose" minOccurs="0">
                <xs:annotation>
                    <xs:documentation>This defines the position of
the quarter-chord point of the airfoil, since that is the reference point
used for the moment coefficient. RPY support has been excluded, requiring
the axes of the airfoil to line up with those of its parent body.</xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:all>
        <xs:attribute name="profile" type="xs:string">
            <xs:annotation>
                <xs:documentation>Only "flat plate" supported right now.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="chord" type="xs:double">
            <xs:annotation>
                <xs:documentation>the chord length in
meters.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="span" type="xs:double">
            <xs:annotation>
                <xs:documentation>the span of the wing
in meters.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="stall_angle" type="xs:double">
            <xs:annotation>
                <xs:documentation>the angle
in degrees upon which the lift and drag performance returns to that of
a flat plate. (this value is ignored if the profile is set to a flat plate).</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="nominal_speed" type="xs:double">
            <xs:annotation>
                <xs:documentation>an approximate
nominal speed in meters per second used to calculate the
Reynolds number around which we design the aerodynamic coefficients.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="visual_geometry" type="xs:boolean" default="true">
            <xs:annotation>
                <xs:documentation>enable or disable automatic drawing of the wing</xs:documentation>
            </xs:annotation>
        </xs:attribute>


        <xs:attribute name="control_surface_chord" type="xs:double" use="required">
            <xs:annotation>
                <xs:documentation>Length of the control surface.</xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute name="control_surface_min_deflection" type="xs:double" use="required">
            <xs:annotation>
                <xs:documentation>Minimum control surface deflection in radians.  Typical is around -0.90</xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute name="control_surface_max_deflection" type="xs:double" use="required">
            <xs:annotation>
                <xs:documentation>Maximum control surface deflection in radians.  Typical is around 0.90</xs:documentation>
            </xs:annotation>
        </xs:attribute>

    </xs:complexType>

    <xs:complexType name="bluff_body">
        <xs:all>
            <xs:element name="origin" type="pose" minOccurs="0">
                <xs:annotation>
                    <xs:documentation>Position of the thrust element.  Example: xyz="0 0 0" rpy="0 0 0".</xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:all>

        <xs:attribute name="name" type="xs:string" use="required"/>

        <xs:attribute name="coefficient_drag_x" type="xs:double" use="required">
            <xs:annotation>
                <xs:documentation>coefficient of drag in the X dimension.</xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute name="coefficient_drag_y" type="xs:double" use="required">
            <xs:annotation>
                <xs:documentation>coefficient of drag in the Y dimension.</xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute name="coefficient_drag_z" type="xs:double" use="required">
            <xs:annotation>
                <xs:documentation>coefficient of drag in the Z dimension.</xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute name="area_x" type="xs:double" use="required">
            <xs:annotation>
                <xs:documentation>area of the bluff body for computing drag on the X axis.</xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute name="area_y" type="xs:double" use="required">
            <xs:annotation>
                <xs:documentation>area of the bluff body for computing drag on the Y axis.</xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute name="area_z" type="xs:double" use="required">
            <xs:annotation>
                <xs:documentation>area of the bluff body for computing drag on the Z axis.</xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute name="visual_geometry" type="xs:boolean" default="true">
            <xs:annotation>
                <xs:documentation>true to enable automatic drawing of the bluff_body as a red cube.</xs:documentation>
            </xs:annotation>
        </xs:attribute>

    </xs:complexType>

    <xs:complexType name="propellor">
        <xs:all>
            <xs:element name="axis" type="axis" minOccurs="0" maxOccurs="1">
                <xs:annotation>
                    <xs:documentation>Axis the thrust element acts on.  For example a propellor facing forward would point in the X-axis and you'd use: xyz="1 0 0". </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="origin" type="pose" minOccurs="0">
                <xs:annotation>
                    <xs:documentation>Position of the thrust element.  Example: xyz="0 0 0" rpy="0 0 0".</xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:all>

        <xs:attribute name="name" type="xs:string" use="required"/>

        <xs:attribute default="-INF" name="lower_limit" type="xs:double">
            <xs:annotation>
                <xs:documentation>input minimum.</xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute default="INF" name="upper_limit" type="xs:double">
            <xs:annotation>
                <xs:documentation>input maximum.</xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute default="1" name="scale_factor_thrust" type="xs:double">
            <xs:annotation>
                <xs:documentation>scales the dimensionless input to Newtons of force.</xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute default="1" name="scale_factor_moment" type="xs:double">
            <xs:annotation>
                <xs:documentation>scales the dimensionless input to newton-meters of torque.</xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute name="visual_geometry" type="xs:boolean" default="true">
            <xs:annotation>
                <xs:documentation>true to enable automatic drawing of the propellor.</xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute name="visual_diameter" type="xs:boolean" default="0.2">
            <xs:annotation>
                <xs:documentation>diameter of the propllor when drawn.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="thrust">
        <xs:all>
            <xs:element name="parent" type="link_reference">
                <xs:annotation>
                    <xs:documentation>String naming the link on
which the force will be applied.</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="axis" type="axis" minOccurs="0" maxOccurs="1">
                <xs:annotation>
                    <xs:documentation>Axis the thrust element acts on.  For example a propellor facing forward would point in the X-axis and you'd use: xyz="1 0 0". </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="origin" type="pose" minOccurs="0">
                <xs:annotation>
                    <xs:documentation>Position of the thrust element.  Example: xyz="0 0 0" rpy="0 0 0".</xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:all>
        <xs:attribute default="-INF" name="lower_limit" type="xs:double"/>
        <xs:attribute default="INF" name="upper_limit" type="xs:double"/>
        <xs:attribute default="1" name="scale_factor" type="xs:double">
            <xs:annotation>
                <xs:documentation>scales the dimensionless
input to Newtons of force.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="added_mass">
        <xs:all>
            <xs:element name="parent" type="link_reference">
                <xs:annotation>
                    <xs:documentation>String naming the link on which
this added-mass is attached.</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="origin" type="pose" minOccurs="0">
                <xs:annotation>
                    <xs:documentation>This defines the position where the added-mass matrix is defined, acting similar to a center-of-mass offset from the parent joint location. RPY is not supported. </xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:all>
        <xs:attribute name="m11" type="xs:double" default="0"/>
        <xs:attribute name="m12" type="xs:double" default="0"/>
        <xs:attribute name="m13" type="xs:double" default="0"/>
        <xs:attribute name="m14" type="xs:double" default="0"/>
        <xs:attribute name="m15" type="xs:double" default="0"/>
        <xs:attribute name="m16" type="xs:double" default="0"/>
        <xs:attribute name="m21" type="xs:double" default="0"/>
        <xs:attribute name="m22" type="xs:double" default="0"/>
        <xs:attribute name="m23" type="xs:double" default="0"/>
        <xs:attribute name="m24" type="xs:double" default="0"/>
        <xs:attribute name="m25" type="xs:double" default="0"/>
        <xs:attribute name="m26" type="xs:double" default="0"/>
        <xs:attribute name="m31" type="xs:double" default="0"/>
        <xs:attribute name="m32" type="xs:double" default="0"/>
        <xs:attribute name="m33" type="xs:double" default="0"/>
        <xs:attribute name="m34" type="xs:double" default="0"/>
        <xs:attribute name="m35" type="xs:double" default="0"/>
        <xs:attribute name="m36" type="xs:double" default="0"/>
        <xs:attribute name="m41" type="xs:double" default="0"/>
        <xs:attribute name="m42" type="xs:double" default="0"/>
        <xs:attribute name="m43" type="xs:double" default="0"/>
        <xs:attribute name="m44" type="xs:double" default="0"/>
        <xs:attribute name="m45" type="xs:double" default="0"/>
        <xs:attribute name="m46" type="xs:double" default="0"/>
        <xs:attribute name="m51" type="xs:double" default="0"/>
        <xs:attribute name="m52" type="xs:double" default="0"/>
        <xs:attribute name="m53" type="xs:double" default="0"/>
        <xs:attribute name="m54" type="xs:double" default="0"/>
        <xs:attribute name="m55" type="xs:double" default="0"/>
        <xs:attribute name="m56" type="xs:double" default="0"/>
        <xs:attribute name="m61" type="xs:double" default="0"/>
        <xs:attribute name="m62" type="xs:double" default="0"/>
        <xs:attribute name="m63" type="xs:double" default="0"/>
        <xs:attribute name="m64" type="xs:double" default="0"/>
        <xs:attribute name="m65" type="xs:double" default="0"/>
        <xs:attribute name="m66" type="xs:double" default="0"/>
    </xs:complexType>

    <xs:complexType name="buoyancy">
        <xs:all>
            <xs:element name="parent" type="link_reference">
                <xs:annotation>
                    <xs:documentation>String naming the link on which
this buoyancy is attached.</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="origin" type="pose" minOccurs="0">
                <xs:annotation>
                    <xs:documentation>This defines the position of the center of buoyancy. RPY is not supported. </xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:all>
        <xs:attribute name="volume" type="xs:double" default="0">
            <xs:annotation>
                <xs:documentation>Volume of the body</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="rho" type="xs:double" default="1">
            <xs:annotation>
                <xs:documentation>Density of the fluid</xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="cable">
        <xs:all>
            <xs:annotation>
                <xs:documentation>Note: the order of the terminator, pulleys, and crossovers DOES MATTER - they specific the kinematic path of the cable.
e.g. terminator - pulley - pulley - crossover - pulley - terminator
</xs:documentation>
            </xs:annotation>
            <xs:element maxOccurs="2" minOccurs="2" name="terminator" type="link_reference_w_pose"/>
            <xs:element form="qualified" maxOccurs="unbounded" minOccurs="0" name="pulley"
                type="pulley">
                <xs:annotation>
                    <xs:documentation>provides a radius about which the cable slides (as if it were frictionless - the actual motion of the pulley is not simulated)</xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:all>
        <xs:attribute default="cable" name="name"/>
        <xs:attribute name="min_length" use="required"/>
        <xs:attribute name="max_length" use="required"/>
    </xs:complexType>
    <xs:complexType name="pulley">
        <xs:attribute name="link" type="xs:string" use="required"/>
        <xs:attribute default="0 0 0" name="xyz" type="matlab_parameter_expression"/>
        <xs:attribute default="0 0 0" name="axis" type="matlab_parameter_expression">
            <xs:annotation>
                <xs:documentation>the cable wraps counter-clockwise (right-hand rule) around the pulley axis</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute default="0" name="radius" type="matlab_parameter_expression">
            <xs:annotation>
                <xs:documentation>All attachments are implemented as (frictionless) pulleys.  Simple attachments are pulleys of radius zero.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="number_of_wraps" type="xs:int">
            <xs:annotation>
                <xs:documentation>Number of times that the cable is wrapped completely around a pulley.  Adds additional 2*pi*radius*number_of_wraps to the computed length of the cable.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>
    <xs:simpleType name="joint_type">
        <xs:restriction base="xs:string">
            <xs:enumeration value="revolute"/>
            <xs:enumeration value="continuous"/>
            <xs:enumeration value="prismatic"/>
            <xs:enumeration value="fixed"/>
            <xs:enumeration value="floating"/>
            <xs:enumeration value="planar"/>
        </xs:restriction>
    </xs:simpleType>

    <xs:complexType name="color">
        <xs:attribute name="rgba" type="xs:string" default="0 0 0 0">
            <xs:annotation>
                <xs:documentation>The color of a material specified by set of four numbers representing red/green/blue/alpha, each in the range of [0,1]. </xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="mass">
        <xs:attribute name="value" type="xs:double" default="0"/>
    </xs:complexType>

    <xs:complexType name="inertia">
        <xs:attribute name="ixx" type="matlab_parameter_expression" default="0"/>
        <xs:attribute name="ixy" type="matlab_parameter_expression" default="0"/>
        <xs:attribute name="ixz" type="matlab_parameter_expression" default="0"/>
        <xs:attribute name="iyy" type="matlab_parameter_expression" default="0"/>
        <xs:attribute name="iyz" type="matlab_parameter_expression" default="0"/>
        <xs:attribute name="izz" type="matlab_parameter_expression" default="0"/>
    </xs:complexType>

    <xs:complexType name="inertial">
        <xs:all>
            <xs:element name="origin" type="pose" minOccurs="0" maxOccurs="1">
                <xs:annotation>
                    <xs:documentation>This is the pose of the inertial reference frame, relative to the link reference frame. The origin of the inertial reference frame needs to be at the center of gravity. The axes of the inertial reference frame do not need to be aligned with the principal axes of the inertia. </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="mass" type="mass" minOccurs="0" maxOccurs="1">
                <xs:annotation>
                    <xs:documentation>The mass of the link is represented by the value attribute of this element </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="inertia" type="inertia" minOccurs="0" maxOccurs="1">
                <xs:annotation>
                    <xs:documentation>The 3x3 rotational inertia matrix, represented in the inertia frame (as defined by the origin tag, e.g., about the center of mass of this link). Because the rotational inertia matrix is symmetric, only 6 above-diagonal elements of this matrix are specified here, using the attributes ixx, ixy, ixz, iyy, iyz, izz. </xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:all>
    </xs:complexType>

    <xs:complexType name="box">
        <xs:attribute name="size" type="xs:string" default="0 0 0"/>
    </xs:complexType>

    <xs:complexType name="cylinder">
        <xs:attribute name="radius" type="xs:double" use="required"/>
        <xs:attribute name="length" type="xs:double" use="required"/>
    </xs:complexType>

    <xs:complexType name="sphere">
        <xs:attribute name="radius" type="xs:double" use="required"/>
    </xs:complexType>

    <xs:complexType name="mesh">
        <xs:attribute name="filename" type="xs:anyURI" use="required"/>
        <xs:attribute name="scale" type="xs:string" default="1 1 1"/>
    </xs:complexType>

    <xs:complexType name="capsule">
        <xs:attribute name="radius" type="xs:double" use="required"/>
        <xs:attribute name="length" type="xs:double" use="required"/>
    </xs:complexType>

    <xs:complexType name="geometry">
        <xs:choice>
            <xs:element name="box" type="box">
                <xs:annotation>
                    <xs:documentation>size attribute contains the three side lengths of the box. The origin of the box is in its center. </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="cylinder" type="cylinder">
                <xs:annotation>
                    <xs:documentation>Specify the radius and length. The origin of the cylinder is in its center.</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="sphere" type="sphere">
                <xs:annotation>
                    <xs:documentation>Specify the radius. The origin of the sphere is in its center. </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="mesh" type="mesh">
                <xs:annotation>
                    <xs:documentation>A trimesh element specified by a filename, and an optional scale that scales the mesh's axis-aligned-bounding-box. The recommended format for best texture and color support is Collada .dae files, though .stl files are also supported. The mesh file is not transferred between machines referencing the same model. It must be a local file. </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="superellipsoid">
                <xs:complexType>
                    <xs:attribute default="1 1 1" name="size" type="xs:string">
                        <xs:annotation>
                            <xs:documentation>3 element double semi-diameter of the ellipse in x,y, and z</xs:documentation>
                        </xs:annotation>
                    </xs:attribute>
                    <xs:attribute default="1 1" name="shape" type="xs:string">
                        <xs:annotation>
                            <xs:documentation>2 element double "squareness" of the ellipsoid in the xy-plane and then the z-plane http://paulbourke.net/geometry/superellipse/ </xs:documentation>
                        </xs:annotation>
                    </xs:attribute>
                </xs:complexType>
            </xs:element>
        </xs:choice>
    </xs:complexType>

    <xs:complexType name="material">
        <xs:sequence>
            <xs:element name="color" type="color" minOccurs="0" maxOccurs="1"/>
        </xs:sequence>
        <xs:attribute name="name" type="xs:string"/>
    </xs:complexType>

    <xs:complexType name="visual">
        <xs:all>
            <xs:element name="origin" type="pose" minOccurs="0" maxOccurs="1"/>
            <xs:element name="geometry" type="geometry" minOccurs="1" maxOccurs="1">
                <xs:annotation>
                    <xs:documentation>The shape of the visual object.</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="material" type="material" minOccurs="0" maxOccurs="1">
                <xs:annotation>
                    <xs:documentation>The material of the visual element. It is allowed to specify a material element outside of the 'link' object, in the top level 'robot' element. From within a link element you can then reference the material by name. </xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:all>
    </xs:complexType>

    <xs:complexType name="collision">
        <xs:all>
            <xs:element name="origin" type="pose" minOccurs="0" maxOccurs="1"/>
            <xs:element name="geometry" type="geometry" minOccurs="1" maxOccurs="1"/>
        </xs:all>
        <xs:attribute name="name" type="xs:string"/>
        <xs:attribute name="group" type="xs:string"/>
    </xs:complexType>

    <xs:complexType name="link">
        <xs:sequence>
            <xs:element name="inertial" type="inertial" minOccurs="0" maxOccurs="1">
                <xs:annotation>
                    <xs:documentation>The inertial properties of the link. </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="visual" type="visual" minOccurs="0" maxOccurs="unbounded">
                <xs:annotation>
                    <xs:documentation>The visual properties of the link. This element specifies the shape of the object (box, cylinder, etc.) for visualization purposes. Note: multiple instances of visual tags can exist for the same link. The union of the geometry they define forms the visual representation of the link. </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="collision" type="collision" minOccurs="0" maxOccurs="unbounded">
                <xs:annotation>
                    <xs:documentation>The collision properties of a link. Note that this can be different from the visual properties of a link, for example, simpler collision models are often used to reduce computation time. Note: multiple instances of collision tags can exist for the same link. The union of the geometry they define forms the collision representation of the link. </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element maxOccurs="unbounded" minOccurs="0" name="sensor" type="sensor"/>
        </xs:sequence>
        <xs:attribute name="name" type="xs:string" use="required">
            <xs:annotation>
                <xs:documentation>The name of the link itself </xs:documentation>
            </xs:annotation>
        </xs:attribute>

        <xs:attribute default="false" name="drake_ignore" type="xs:boolean">
            <xs:annotation>
                <xs:documentation>set to true to instruct the drake parser to skip this link</xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>


    <xs:complexType name="link_reference">
        <xs:attribute name="link" type="xs:string" use="required"/>
    </xs:complexType>

    <xs:complexType name="link_reference_w_pose">
        <xs:attribute name="link" type="xs:string" use="required"/>
        <xs:attribute default="0 0 0" name="xyz" type="matlab_parameter_expression"/>
        <xs:attribute default="0 0 0" name="rpy" type="matlab_parameter_expression"/>
    </xs:complexType>

    <xs:complexType name="axis">
        <xs:attribute name="xyz" type="matlab_parameter_expression" default="1 0 0"/>
    </xs:complexType>

    <xs:complexType name="dynamics">
        <xs:attribute name="damping" type="matlab_parameter_expression" default="0">
            <xs:annotation>
                <xs:documentation>The physical damping value of the joint</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="friction" type="matlab_parameter_expression">
            <xs:annotation>
                <xs:documentation>coulomb friction coefficient.

total friction force is a piecewise linear approximation of sgn(qd)*Fc + qd*Fd:

f_friction = min(1,max(-1,qd./m.coulomb_window')).*m.coulomb_friction' + m.damping'.*qd;

</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="coulomb_window" type="matlab_parameter_expression">
            <xs:annotation>
                <xs:documentation>determines the threshold in qd when the coulomb term saturates (F_c = sgn(qd)*coulomb_friction.

total friction force is a piecewise linear approximation of sgn(qd)*Fc + qd*Fd:

f_friction = min(1,max(-1,qd./m.coulomb_window')).*m.coulomb_friction' + m.damping'.*qd;
</xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="limit">
        <xs:attribute name="lower" type="matlab_parameter_expression" default="-inf">
            <xs:annotation>
                <xs:documentation>An attribute specifying the lower joint limit (radians for revolute joints, meters for prismatic joints). Omit if joint is continuous.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="upper" type="matlab_parameter_expression" default="inf">
            <xs:annotation>
                <xs:documentation>An attribute specifying the upper joint limit (radians for revolute joints, meters for prismatic joints). Omit if joint is continuous. </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="effort" type="matlab_parameter_expression" default="inf">
            <xs:annotation>
                <xs:documentation>An attribute for enforcing the maximum joint effort</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute default="-inf" name="effort_min" type="matlab_parameter_expression">
            <xs:annotation>
                <xs:documentation>maximum joint effort.  If both 'effort' and 'effort_min' are specified, then effort_min takes priority.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute default="inf" name="effort_max" type="matlab_parameter_expression">
            <xs:annotation>
                <xs:documentation>maximum joint effort.  If both 'effort' and 'effort_max' are specified, then effort_max takes priority.</xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="joint">
        <xs:all>
            <xs:element name="origin" type="pose" minOccurs="0" maxOccurs="1">
                <xs:annotation>
                    <xs:documentation>This is the transform from the parent link to the child link. The joint is located at the origin of the child link, as shown in the figure above. </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="parent" type="link_reference" minOccurs="1" maxOccurs="1">
                <xs:annotation>
                    <xs:documentation>Parent link name</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="child" type="link_reference" minOccurs="1" maxOccurs="1">
                <xs:annotation>
                    <xs:documentation>Child link name</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="axis" type="axis" minOccurs="0" maxOccurs="1">
                <xs:annotation>
                    <xs:documentation>The joint axis specified in the joint frame. This is the axis of rotation for revolute joints, the axis of translation for prismatic joints, and the surface normal for planar joints. The axis is specified in the joint frame of reference. Fixed and floating joints do not use the axis field. </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="dynamics" type="dynamics" minOccurs="0" maxOccurs="1">
                <xs:annotation>
                    <xs:documentation>An element specifying physical properties of the joint. These values are used to specify modeling properties of the joint, particularly useful for simulation. </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="limit" type="limit" minOccurs="0" maxOccurs="1"/>
        </xs:all>
        <xs:attribute name="name" type="xs:string" use="required"/>
        <xs:attribute name="type" type="joint_type" use="required">
            <xs:annotation>
                <xs:documentation>Specifies the type of joint, where type can be one of the following:

    revolute - a hinge joint that rotates along the axis and has a limited range specified by the upper and lower limits.
    continuous - a continuous hinge joint that rotates around the axis and has no upper and lower limits
    prismatic - a sliding joint that slides along the axis, and has a limited range specified by the upper and lower limits.
    fixed - This is not really a joint because it cannot move. All degrees of freedom are locked. This type of joint does not require the axis, calibration, dynamics, limits or safety_controller.
    floating - This joint allows motion for all 6 degrees of freedom.
    planar - This joint allows motion in a plane perpendicular to the axis. </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute default="1" name="has_position_sensor" type="xs:boolean" use="optional"/>
        <xs:attribute default="false" name="drake_ignore" type="xs:boolean">
            <xs:annotation>
                <xs:documentation>set to true to instruct the drake parser to skip this link</xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="joint_reference">
        <xs:attribute name="name" type="xs:string"/>
    </xs:complexType>
    <xs:complexType name="gazebo_sensor">
        <xs:sequence>
            <xs:element name="pose" type="matlab_parameter_expression"/>
        </xs:sequence>
        <xs:attribute name="name" type="xs:string"/>
        <xs:attribute name="type" type="sensor_type"/>
    </xs:complexType>
    <xs:complexType name="gazebo">
        <xs:sequence>
            <xs:element maxOccurs="unbounded" minOccurs="0" name="sensor" type="gazebo_sensor"/>
        </xs:sequence>
        <xs:attribute name="reference" type="xs:string"/>
    </xs:complexType>
    <xs:complexType name="sensor">
        <xs:all>
            <xs:element maxOccurs="1" minOccurs="0" name="pose" type="pose"/>
        </xs:all>
        <xs:attribute name="name" type="xs:string"/>
        <xs:attribute name="type" type="sensor_type"/>
    </xs:complexType>
    <xs:simpleType name="sensor_type">
        <xs:restriction base="xs:string">
            <xs:enumeration value="imu"/>
            <xs:enumeration value="contact"/>
        </xs:restriction>
    </xs:simpleType>
    <xs:complexType name="transmission">
        <xs:all>
            <xs:element maxOccurs="1" minOccurs="1" name="joint" type="joint_reference"/>
            <xs:element maxOccurs="1" minOccurs="1" name="actuator" type="actuator"/>
            <xs:element default="1" maxOccurs="1" minOccurs="0" name="mechanicalReduction"
                type="xs:double"/>
        </xs:all>
        <xs:attribute name="name" type="xs:string"/>
        <xs:attribute name="type" type="transmission_type"/>
    </xs:complexType>
    <xs:complexType name="actuator">
        <xs:attribute name="name" type="xs:string"/>
    </xs:complexType>
    <xs:simpleType name="transmission_type">
        <xs:restriction base="xs:string">
            <xs:enumeration value="SimpleTransmission"/>
        </xs:restriction>
    </xs:simpleType>
    <xs:element name="robot">
        <xs:complexType>
            <xs:sequence minOccurs="0" maxOccurs="unbounded">
                <xs:element name="joint" type="joint" minOccurs="0" maxOccurs="unbounded">
                    <xs:annotation>
                        <xs:documentation>The joint element describes the kinematics and dynamics of the joint and also specifies the safety limits of the joint. </xs:documentation>
                    </xs:annotation>
                </xs:element>
                <xs:element name="link" type="link" minOccurs="0" maxOccurs="unbounded">
                    <xs:annotation>
                        <xs:documentation>The link element describes a rigid body with an inertia, visual features, ...</xs:documentation>
                    </xs:annotation>
                </xs:element>

                <xs:element maxOccurs="unbounded" minOccurs="0" name="transmission"
                    type="transmission"/>
                <xs:element name="material" type="material" minOccurs="0" maxOccurs="unbounded">
                    <xs:annotation>
                        <xs:documentation>The material of the visual element. It is allowed to specify a material element outside of the 'link' object, in the top level 'robot' element. From within a link element you can then reference the material by name. </xs:documentation>
                    </xs:annotation>
                </xs:element>
                <xs:element maxOccurs="unbounded" minOccurs="0" name="parameter" type="parameter">
                    <xs:annotation>
                        <xs:documentation>A robot parameter, which can be referenced in matlab_parameter_expression types.  For example, a parameter with name="m1" could be references in mass value="$m1".  </xs:documentation>
                    </xs:annotation>
                </xs:element>
                <xs:element maxOccurs="unbounded" minOccurs="0" name="loop_joint" type="loop_joint">
                    <xs:annotation>
                        <xs:documentation>Adds support for simple closed-loop kinematic chains. For an example, see
examples/SimpleFourBar/FourBar.urdf

Note: We do not support dynamics or torque at the loop_joint
yet. (see bug 921)</xs:documentation>
                    </xs:annotation>
                </xs:element>
                <xs:element name="force_element" type="force_element" maxOccurs="unbounded"
                    minOccurs="0">
                    <xs:annotation>
                        <xs:documentation>Adds dynamic, force-producing elements like springs and aerodynamics</xs:documentation>
                    </xs:annotation>
                </xs:element>
                <xs:element maxOccurs="unbounded" minOccurs="0" name="collision_filter_group"
                    type="collision_filter_group"/>
                <xs:element maxOccurs="unbounded" minOccurs="0" name="frame">
                    <xs:complexType>
                        <xs:complexContent>
                            <xs:extension base="link_reference_w_pose">
                                <xs:attribute name="name"/>
                            </xs:extension>
                        </xs:complexContent>
                    </xs:complexType>
                </xs:element>
            </xs:sequence>
            <xs:attribute name="name" type="xs:string" use="required"/>

            <xs:attribute name="version" type="xs:string" default="1.0"/>
        </xs:complexType>
    </xs:element>
    <xs:complexType name="collision_filter_group_reference">
        <xs:attribute name="collision_filter_group"/>
    </xs:complexType>
    <xs:complexType name="collision_filter_group">
        <xs:annotation>
            <xs:documentation>Provides a means to exclude certain pairs of bodies from collision detection and closest distance computations. A collision filter group can contain one or more links, and a link may belong to any number of collision filter groups. Given two links A and B by default they are specified to be checked for collision. If they are adjacent in the kinematic tree, then they are not checked for collision unless one is the world link and the jointing connecting them is a floating base joint. If link A is in a collision filter group Alpha and link B is in a collision filter group Beta and Beta is in Alpha.ignored_collision_filter group then A and B are not checked for collision. The same also holds in reverse, i.e. if Alpha is in Beta.ignored_collision_filter_group then links A and B are not in collision. However only one of the two conditions is necessary for excluding the pair of bodies from collision detection.</xs:documentation>
        </xs:annotation>
        <xs:sequence>
            <xs:element name="member" type="link_reference" maxOccurs="unbounded" minOccurs="0">
                <xs:annotation>
                    <xs:documentation>Specifies that a link belongs to this collision filter group.</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="ignored_collision_filter_group"
                type="collision_filter_group_reference" maxOccurs="unbounded" minOccurs="0">
                <xs:annotation>
                    <xs:documentation>Specifies that collisions between members of this collision filter group and those of another collision filter group should be ignored.</xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:sequence>
        <xs:attribute form="unqualified" name="name" type="xs:string" use="required"/>
    </xs:complexType>
</xs:schema>