.URDFModelica.Documentation.Robot .URDFModelica.Documentation.RobotPackage URDFModelica/Robots contains the prototypes for robots as specified by the Unified Robot Description Format URDF ROS Wiki.
BaseURDF is the model that connects links and joints together to from the robot as defined by URDF. When a new robot package is created, one copy of BaseURDF is created and all links and joints added. The links are connected to the joints to form the kinematic chains. The first link is also connected to a frame_a on the left. All links that are leaves of kinematic chains are connected to a vector of frame_b on the right of the model. Additionally, rotational and translational flanges are propagated to the outside for every continuous, revolute and prismatic joint. In order to have the correct array sizes, integer parameters are automatically calculated. For easier reference, the flange number is also given as parameter to these joints and shown in the icons. Even so not used in this package, the number of collision links is calculated too. The icon depends on the presence or absence of the -s option on package creation. The diagram size is automatically adjusted to show all elements. This is the final model entirely relying on the URDF source description, the further two Modelica models are suggestions for usage.
RunURDF builds an environment around BaseURDF. There is a Modelica.Mechanics.MultiBody.World, and outside inputs for position and angle of joints. RunURDF is one possible model to compile as FMU and use to design robot controllers in the modeling and simulation software of your choice. A mobile robot (default) is connected to the Multibody World through a Modelica.Mechanics.MultiBody.Joints.FreeMotion with r_rel_a(start = {0.0, 0.0, 1.0}) and angles_start = {0.0, 0.0, 0.0}. The leaves of kinematic chains are connected to collisionPoints (see Links explanation) to prevent mobile robots (their kinematic chains in general end with wheels) from falling through the ground. A stationary robot (-s) connects the BaseURDF directly to the Multibody World. Option -v for the Python script selects the RunURDF_Visualization2 template model that disables the Standard Library Visualizers and includes the DLR Visualization 2 setup.
TestURDF is a model to quickly check that the package has been created correctly by providing some simple inputs to all needed signals.
The Robot model and parameter record is not used when creating a package with Python. Instead it is a generic robot model that is defined by a single parameter record. When calling the Python script, such a record is created and saved at the location specified by the -o option (default is robot name in current folder). It not only compiles the arrays of links and joints, it also contains two matrices. connectionMatrix[numJoints,2] lists the connected parent and child link for every joint. moveableJoints[numAxes,2] has the joint number and moveable axis number for every joint that is not fixed. As demonstrated in the Examples.GenericRobotModel.GenericRobot example, a complete robot can be simulated with only a few lines of code using arrays of variable length instead of variable structure models that are not allowed in Modelica. The advantage of few lines of code and easy switching between robots (replace the record, that's all) has the drawback, that all links and joints must be equal. The link array is declared replaceable such that you can easily replace it with Link_Visualization2 if you want to visualize the robot with DLR Visualization 2.