Set initial joint at launch gazebo (#681)

* Possible to set initial configuration in Gazebo
* Change initial pose to the upright pose

---------

Co-authored-by: Felix Exner (fexner) <exner@fzi.de>

ur_gazebo/launch/inc/ur_control.launch.xml

@@ -29,6 +29,9 @@
   <arg name="spawn_z" default="0.1" doc="At which height the model should be spawned. NOTE: lower values will cause the robot to collide with the ground plane." />
   <arg name="start_gazebo" default="true" doc="If true, Gazebo will be started. If false, Gazebo will be assumed to have been started elsewhere." />
 
+  <!--Setting initial configuration -->
+  <arg name="initial_joint_positions" default=" -J shoulder_pan_joint 0.0  -J shoulder_lift_joint -1.57 -J elbow_joint 0.0 -J wrist_1_joint -1.57 -J wrist_2_joint 0.0 -J wrist_3_joint 0.0" doc="Initial joint configuration of the robot"/>
+
   <!-- Load controller settings -->
   <rosparam file="$(arg controller_config_file)" command="load"/>
 
@@ -45,7 +48,9 @@
       -urdf
       -param $(arg robot_description_param_name)
       -model $(arg gazebo_model_name)
-      -z $(arg spawn_z)"
+      -z $(arg spawn_z)
+      $(arg initial_joint_positions)
+      "
     output="screen" respawn="false" />
 
   <!-- Load and start the controllers listed in the 'controllers' arg. -->