Adds .panda_simulation folder creation functionality

The robot_control_node.cpp file now first tries to add the .panda_simulation
folder before throwing an error.

launch/simulation.launch

@@ -47,6 +47,6 @@
     <node name="joint_state_desired_publisher" pkg="topic_tools" type="relay" args="joint_states joint_states_desired" />
 
     <!-- launch robot control node for moveit motion planning -->
-    <node pkg="panda_simulation" type="robot_control_node" name="robot_control_node" />
+    <node pkg="panda_simulation" type="robot_control_node" name="robot_control_node" output="screen"/>
 
 </launch>
\ No newline at end of file

src/robot_control_node.cpp

@@ -80,9 +80,25 @@ int main(int argc, char **argv)
 
     if (!fs::exists(app_directory) && !fs::is_directory(app_directory))
     {
-      ROS_ERROR_STREAM(app_directory << " does not exist");
+      ROS_WARN_STREAM(app_directory << " does not exist");
+
+      // Create .panda_simulation directory
+      std::string path(getenv("HOME"));
+      path += "/.panda_simulation";
+      ROS_INFO("Creating %s collision objects directory.", path);
+      try
+      {
+        boost::filesystem::create_directory(path);
+      }
+      catch (const std::exception&)
+      {
+        ROS_ERROR(
+          "%s directory could not be created."
+          "Please create this directory yourself "
+          "if you want to specify collision objects.", path.c_str());
         return -1;
       }
+    }
 
     std::vector<moveit_msgs::CollisionObject> collision_objects;
     ROS_INFO_STREAM(app_directory << " is a directory containing:");