✨ update urdf and dependencies

assets/rotary_cartpole/rotary_cartpole.urdf

@@ -36,9 +36,9 @@
   <link name="arm">
     <inertial>
       <origin xyz="0.00005 0.0065 0.00563" rpy="0 0 0"/>
-      <mass value="0.150"/>
-      <inertia ixx="4.05e-05" iyy="1.17e-05" izz="3.66e-05"
-               ixy="0.0" iyz="1.08e-07" ixz="0.0"/>
+      <mass value="0.010"/>
+      <inertia ixx="2.70e-06" iyy="7.80e-07" izz="2.44e-06"
+               ixy="0.0" iyz="7.20e-08" ixz="0.0"/>
     </inertial>
     <visual>
       <origin xyz="0.006947 -0.00395 -0.14796" rpy="0 0 0"/>
@@ -73,7 +73,7 @@
            Tip at (0.07, -0.07, 0) → 45° diagonal in +X/-Y.
            CoM = (5×0.035+10×0.07)/15 = 0.0583 along both +X and -Y.
            Inertia tensor rotated 45° to match diagonal rod axis. -->
-      <origin xyz="0.0583 -0.0583 0.0" rpy="0 0 0"/>
+      <origin xyz="0.1583 -0.0983 -0.0" rpy="0 0 0"/>
       <mass value="0.015"/>
       <inertia ixx="6.16e-06" iyy="6.16e-06" izz="1.23e-05"
                ixy="6.10e-06" iyz="0.0" ixz="0.0"/>
@@ -93,13 +93,14 @@
   </link>
 
   <!-- Pendulum joint: arm → pendulum, bearing axis along Y.
-       Joint origin corrected from mesh analysis (Fusion2URDF was 180mm off). -->
+       Joint origin corrected from mesh analysis (Fusion2URDF was 180mm off).
+       rpy pitch +90° so qpos=0 = pendulum hanging down (gravity-stable). -->
   <joint name="pendulum_joint" type="continuous">
-    <origin xyz="0.000052 0.019274 0.014993" rpy="0 0 0"/>
+    <origin xyz="0.000052 0.019274 0.014993" rpy="0 1.5708 0"/>
     <parent link="arm"/>
     <child link="pendulum"/>
     <axis xyz="0 -1 0"/>
-    <dynamics damping="0.0005"/>
+    <dynamics damping="0.0001"/>
   </joint>
 
 </robot>