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RobWorkProject
23.9.11-
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RobWorkProject
23.9.11-
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The dynamic workcell (DWC) XML file format have suffix .dwc.xml and follow the rules of standard XML. A dynamic workcell can be loaded with rwsim::loaders::DynamicWorkCellLoader::load() :
DynamicWorkCell::Ptr dwc = DynamicWorkCellLoader::load("DynamicWorkCellFile.dwc.xml");
The dynamic workcell file referes to an existing workcell file, and adds dynamic concepts such as dynamic bodies, dynamic devices, mass, inertia, material properties, constraints, gravity, controllers, and sensors.
The DynamicWorkCell element is the root element in the fileformat and refers to the underlying WorkCell file:
<DynamicWorkcell workcell="pih.wc.xml">
...
</DynamicWorkcell>
In the following the different possible elements in the DWC format will be described.
Element DynamicWorkCell
Attributes
Child elements:
Example
<DynamicWorkcell workcell="pih.wc.xml">
...
</DynamicWorkcell>
The dynamic workcell can be split into multiple files. The extension of a included file should be .xml (and not dwc.xml as it is not a valid dynamic workcell on its own).
Element Include
Attributes
Example
<Include file="include.xml" />
The included file must have a root element called IncludeData:
<IncludeData>
...
</IncludeData>
Everything inside the IncludeData element is interpreted as if it was inserted directly in the .dwc.xml file instead of the Include tag.
For dynamic simulation different Physics Engines can be used. The PhysicsEngine element allows modification of parameters that are specific to the PhysicsEngine used. See also rwsim::simulator::PhysicsEngine .
Element PhysicsEngine
Child elements:
Child element Property
Attributes
Example The following example shows an example with properties for the Open Dynamics Engine (see rwsim::simulator::ODESimulator and ODE documentation for further information). All properties are optional, and the example shows the default values used for ODE.
<PhysicsEngine>
<Property name="StepMethod">WorldStep</Property> <!-- WorldQuickStep/WorldStep/WorldFast1 -->
<Property name="WorldCFM" type="float">0.0000001</Property>
<Property name="WorldERP" type="float">0.2</Property>
<Property name="SpaceType">Simple</Property> <!-- QuadTree/Simple/HashTable -->
<Property name="MaxIterations" type="int">20</Property>
<Property name="ContactSurfaceLayer" type="float">0.0001</Property>
<Property name="MaxSepDistance" type="float">0.0005</Property>
<Property name="MaxPenetration" type="float">0.0005</Property>
<Property name="MaxCorrectingVelocity" type="float">0.1</Property>
</PhysicsEngine>
For similar options for the RobWorkPhysicsEngine (RWPE), please see rwsimlibs::rwpe::RWPEIsland::getDefaultPropertyMap documentation.
Set the gravity in world coordinates.
Element Gravity
Example
<Gravity>0 0 -9.82</Gravity>
Each body in a dynamic workcell must be associated to a material and object type. These determine how bodies interact with each other by defining friction and restitution. The material database is made of the following four elements:
In practice the material database can be big, and often the materials are defined in a separate file (often named DynamicMaterialDataBase.xml) using the Include element.
Defines names and an optional descriptions of all materials used in the dynamic workcell. See also rwsim::dynamics::MaterialDataMap .
Element MaterialData
Child elements:
Child element Material
Attributes
Child elements:
Example
The following example shows the definition of a single material.
<MaterialData>
<Default>Plastic</Default>
<Material id="Plastic">
<Description>Optional description</Description>
</Material>
</MaterialData>
Definition of friction between different materials defined in MaterialData . See also rwsim::dynamics::FrictionData .
Element FrictionMap
Child elements:
Child element Pair
Attributes
Child elements:
Child element FrictionData
Attributes
Child elements:
Example
<FrictionMap>
<Pair first="Plastic" second="Plastic">
<FrictionData type="Coulomb">
<Mu>0.4</Mu>
</FrictionData>
</Pair>
</FrictionMap>
Definition of different object types. This is primarily used for defining restitution between objects. See also rwsim::dynamics::ContactDataMap .
Element ObjectTypeData
Child elements:
Child element ObjectType
Attributes
Child elements:
Example
<ObjectTypeData>
<Default>hardObj</Default>
<ObjectType id="hardObj">
<Description>A hard object. with low elasticity</Description>
</ObjectType>
</ObjectTypeData>
Definition of restitution coefficients between different object types defined in ObjectTypeData . See also rwsim::dynamics::ContactDataMap::NewtonData .
Element ContactMap
Child elements:
Child element Pair
Attributes
Child elements:
Element ContactData
Attributes
Child elements:
Example
<ContactMap>
<Pair first="hardObj" second="hardObj">
<ContactData type="Newton">
<cr>0.0</cr>
</ContactData>
</Pair>
</ContactMap>
Bodies that should be a part of the simulation must be defined in the dynamic workcell. There are three available types:
Fixed bodies will typically be static environment, such as floors and walls. See also rwsim::dynamics::FixedBody .
Element FixedBody
Attributes
Child elements:
Example
<FixedBody frame="Floor" />
Kinematic bodies can be controlled directly with velocities. See also rwsim::dynamics::KinematicBody .
Element KinematicBody
Attributes
Child elements:
Example
<KinematicBody frame="MovingBody">
<MaterialID>Plastic</MaterialID>
</KinematicBody>
Rigid bodies moves due to forces acting on the bodies. Hence they require specification of dynamic parameters as mass and inertia. See also rwsim::dynamics::RigidBody .
Element RigidBody
Attributes
Child elements:
Child element Associate
Attributes
Example
<RigidBody frame="DynBodyFrame">
<Mass>0.1</Mass>
<EstimateInertia />
<Integrator>Euler</Integrator>
<Associate object="DynBodyGeometry" />
</RigidBody>
Devices that should be a part of the simulation must be defined in the dynamic workcell. There are two available types:
Please note that a Body that is part of a device is called a Link. A Body in the dynamic workcell format referes to a body that is not part of a device (it is free). A Link is part of a device and has its motion constrained. Because of this, the syntax for a Link and a Body is equivalent in practice.
See also rwsim::dynamics::KinematicDevice .
Element KinematicDevice
Attributes
Child elements:
Child element RefBase
Attributes
Example
<KinematicDevice device="Robot">
<KinematicBase frame="Base" />
<KinematicJoint object="Joint0">
<Mass>0</Mass>
<COG>0 0 0</COG>
<Inertia>0 0 0 0 0 0 0 0 0</Inertia>
<MaterialID>Plastic</MaterialID>
</KinematicJoint>
...
</KinematicDevice>
See also rwsim::dynamics::RigidDevice .
Element RigidDevice
Attributes
Child elements:
Child element ForceLimit
Attributes
Example
<RigidDevice device="UR1">
<ForceLimit joint="Joint0">1000</ForceLimit>
<FixedBase frame="Base">
<MaterialID>Plastic</MaterialID>
</FixedBase>
<Link object="Joint0">
<Mass>3.8</Mass>
<EstimateInertia/>
<MaterialID>Plastic</MaterialID>
</Link>
...
</RigidDevice>
The SuctionCup element is not documented yet.
The only way to constraint bodies is to use devices. In some cases it might however be useful to constrain arbitrary bodies without requiring that the bodies are part of the same device. This could for instance be if one wants to model a spring. The Constraint element is the equivalent of a rwsim::dynamics::Constraint objects.
Element Constraint
Attributes
Child elements:
Note the Spring element can be defined under the Constraint or after the Constraint with a reference to the name of the constraint.
Example of a Fixed constraint:
<Constraint name="FixedConstraint" type="Fixed" parent="Parent" child="Child" />
Example of a non-fixed constraint (the spring works for the one linear and two angular directions that are not constrained by the PrismaticUniversal constraint):
<Constraint name="ComplianceConstraint" type="PrismaticUniversal" parent="Parent" child="Child">
<Transform3D>
<Pos>0 0 0.01</Pos>
<RPY>0 0 0</RPY>
</Transform3D>
<Spring>
<Compliance>
0.0005 0 0
0 0.5 0
0 0 0.5
</Compliance>
<Damping>
50 0 0
0 0.1 0
0 0 0.1
</Damping>
</Spring>
</Constraint>
It is possible to attach a spring to a constraint as described in Constraints . If the spring is defined outside the Constraint tags, it must refer to a constraint by name.
Element Spring
Attributes
Child elements:
Example of a spring attached to a PrismaticUniversal constraint (the spring works for the one linear and two angular directions that are not constrained by the PrismaticUniversal constraint):
<Spring constraint="ComplianceConstraint">
<Compliance>
0.0005 0 0
0 0.5 0
0 0 0.5
</Compliance>
<Damping>
50 0 0
0 0.1 0
0 0 0.1
</Damping>
</Spring>
Not documented yet.
Not documented yet.
1.9.1