Random ball spawn at safe positions, remove ball from world SDF

Author: Dhiren8202

ros2_ws/interbotix_xslocobot_descriptions/worlds/ball.sdf

@@ -0,0 +1,15 @@
+<?xml version="1.0" ?>
+<sdf version="1.6">
+  <model name="ball">
+    <link name="link">
+      <inertial><mass>0.1</mass><inertia><ixx>0.0001</ixx><iyy>0.0001</iyy><izz>0.0001</izz></inertia></inertial>
+      <collision name="collision">
+        <geometry><sphere><radius>0.1</radius></sphere></geometry>
+      </collision>
+      <visual name="visual">
+        <geometry><sphere><radius>0.1</radius></sphere></geometry>
+        <material><ambient>1 0.2 0.2 1</ambient><diffuse>1 0.2 0.2 1</diffuse></material>
+      </visual>
+    </link>
+  </model>
+</sdf>

ros2_ws/interbotix_xslocobot_descriptions/worlds/locobot_world.sdf

@@ -278,19 +278,5 @@
       </link>
     </model>
 
-    <model name="ball">
-      <pose>3.0 3.0 0.1 0 0 0</pose>
-      <link name="link">
-        <inertial><mass>0.1</mass><inertia><ixx>0.0001</ixx><iyy>0.0001</iyy><izz>0.0001</izz></inertia></inertial>
-        <collision name="collision">
-          <geometry><sphere><radius>0.1</radius></sphere></geometry>
-        </collision>
-        <visual name="visual">
-          <geometry><sphere><radius>0.1</radius></sphere></geometry>
-          <material><ambient>1 0.2 0.2 1</ambient><diffuse>1 0.2 0.2 1</diffuse></material>
-        </visual>
-      </link>
-    </model>
-
   </world>
 </sdf>

ros2_ws/locobot_gazebo/launch/locobot_gazebo.launch.py

@@ -1,5 +1,13 @@
 import os
 import subprocess
+import random
+
+# Safe ball spawn positions (clear of obstacles)
+SAFE_POSITIONS = [
+    (3.0, 3.0), (3.0, -3.0), (-3.0, 3.0), (-3.0, -3.0),
+    (3.5, 0.0), (-3.5, 0.0), (0.0, 3.5), (0.0, -3.5),
+    (2.0, 3.5), (3.5, 2.0), (-2.0, 3.5), (3.5, -2.0),
+]
 from ament_index_python.packages import get_package_share_directory
 from launch import LaunchDescription
 from launch.actions import IncludeLaunchDescription, SetEnvironmentVariable, TimerAction
@@ -128,6 +136,24 @@ def generate_launch_description():
         ),
 
 
+        TimerAction(
+            period=6.0,
+            actions=[
+                Node(
+                    package='ros_gz_sim',
+                    executable='create',
+                    arguments=[
+                        '-name', 'ball',
+                        '-file', os.path.join(desc_pkg, 'worlds', 'ball.sdf'),
+                        '-x', str((_pos := random.choice(SAFE_POSITIONS))[0]),
+                        '-y', str(_pos[1]),
+                        '-z', '0.1',
+                    ],
+                    output='screen',
+                ),
+            ]
+        ),
+
         TimerAction(
             period=8.0,
             actions=[