From bf84be6420ff7736d902c8abd0b0ba56083378e0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?St=C3=A9phane=20Caron?= <stephane.caron@inria.fr>
Date: Wed, 31 Jul 2024 10:51:59 +0200
Subject: [PATCH] Add an empty visual box to all virtual links

See https://github.com/upkie/upkie_description/pull/19#issuecomment-2259933854

Fixes https://github.com/upkie/upkie_description/issues/20
---
 urdf/upkie.urdf                        | 64 +++++++++++++++++++-------
 urdf/upkie_camera.urdf                 | 64 +++++++++++++++++++-------
 xacro/left_leg.xacro                   | 12 ++---
 xacro/right_leg.xacro                  | 12 ++---
 xacro/torso.xacro                      |  8 +---
 xacro/upkie.xacro                      |  2 +-
 xacro/upkie_camera.xacro               |  2 +-
 xacro/utils/virtual_link.xacro         | 19 ++++++++
 xacro/utils/virtual_link_inertia.xacro | 13 ------
 9 files changed, 125 insertions(+), 71 deletions(-)
 create mode 100644 xacro/utils/virtual_link.xacro
 delete mode 100644 xacro/utils/virtual_link_inertia.xacro

diff --git a/urdf/upkie.urdf b/urdf/upkie.urdf
index 16a15d1..ff22ce1 100644
--- a/urdf/upkie.urdf
+++ b/urdf/upkie.urdf
@@ -40,9 +40,13 @@ Conventions in this file are detailed in:
     <color rgba="0.93 0.64 0.52 0.8"/>
   </material>
   <link name="base">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -74,9 +78,13 @@ Conventions in this file are detailed in:
   </joint>
   <!-- IMU -->
   <link name="imu">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -437,9 +445,13 @@ Conventions in this file are detailed in:
     <origin rpy="3.141592653589793 0 0" xyz="0 0 -0.0015"/>
   </joint>
   <link name="left_anchor">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -532,9 +544,13 @@ Conventions in this file are detailed in:
     <origin rpy="0 0 0" xyz="0 0 0.0209"/>
   </joint>
   <link name="left_contact">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -548,9 +564,13 @@ Conventions in this file are detailed in:
     <origin rpy="1.5707963267948966 0 0" xyz="0 0.047 0"/>
   </joint>
   <link name="left_wheel_center">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -861,9 +881,13 @@ Conventions in this file are detailed in:
     <origin rpy="3.141592653589793 0 0" xyz="0 0 -0.0015"/>
   </joint>
   <link name="right_anchor">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -956,9 +980,13 @@ Conventions in this file are detailed in:
     <origin rpy="0 0 0" xyz="0 0 0.0209"/>
   </joint>
   <link name="right_contact">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -972,9 +1000,13 @@ Conventions in this file are detailed in:
     <origin rpy="1.5707963267948966 0 0" xyz="0 0.047 0"/>
   </joint>
   <link name="right_wheel_center">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
diff --git a/urdf/upkie_camera.urdf b/urdf/upkie_camera.urdf
index d52eef7..97623bf 100644
--- a/urdf/upkie_camera.urdf
+++ b/urdf/upkie_camera.urdf
@@ -40,9 +40,13 @@ Conventions in this file are detailed in:
     <color rgba="0.93 0.64 0.52 0.8"/>
   </material>
   <link name="base">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -74,9 +78,13 @@ Conventions in this file are detailed in:
   </joint>
   <!-- IMU -->
   <link name="imu">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -461,9 +469,13 @@ Conventions in this file are detailed in:
     <origin rpy="3.141592653589793 0 0" xyz="0 0 -0.0015"/>
   </joint>
   <link name="left_anchor">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -556,9 +568,13 @@ Conventions in this file are detailed in:
     <origin rpy="0 0 0" xyz="0 0 0.0209"/>
   </joint>
   <link name="left_contact">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -572,9 +588,13 @@ Conventions in this file are detailed in:
     <origin rpy="1.5707963267948966 0 0" xyz="0 0.047 0"/>
   </joint>
   <link name="left_wheel_center">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -885,9 +905,13 @@ Conventions in this file are detailed in:
     <origin rpy="3.141592653589793 0 0" xyz="0 0 -0.0015"/>
   </joint>
   <link name="right_anchor">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -980,9 +1004,13 @@ Conventions in this file are detailed in:
     <origin rpy="0 0 0" xyz="0 0 0.0209"/>
   </joint>
   <link name="right_contact">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
@@ -996,9 +1024,13 @@ Conventions in this file are detailed in:
     <origin rpy="1.5707963267948966 0 0" xyz="0 0.047 0"/>
   </joint>
   <link name="right_wheel_center">
-    <!-- virtual link -->
+    <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+    <visual>
+      <geometry>
+        <box size="0 0 0"/>
+      </geometry>
+    </visual>
     <inertial>
-      <!-- mass should not be zero [1] -->
       <mass value="0.001"/>
       <origin rpy="0 0 0" xyz="0 0 0"/>
       <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
diff --git a/xacro/left_leg.xacro b/xacro/left_leg.xacro
index 3e79dd6..f0eee40 100644
--- a/xacro/left_leg.xacro
+++ b/xacro/left_leg.xacro
@@ -331,9 +331,7 @@
             <origin rpy="3.141592653589793 0 0" xyz="0 0 -0.0015" />
         </joint>
 
-        <link name="left_anchor">
-            <xacro:virtual_link_inertia />
-        </link>
+        <xacro:virtual_link name="left_anchor" />
 
         <joint name="left_anchor_fix" type="fixed">
             <parent link="left_ankle_mj5208_stator" />
@@ -429,9 +427,7 @@
             <origin rpy="0 0 0" xyz="0 0 0.0209" />
         </joint>
 
-        <link name="left_contact">
-            <xacro:virtual_link_inertia />
-        </link>
+        <xacro:virtual_link name="left_contact" />
 
         <joint name="left_contact_fix" type="fixed">
             <parent link="left_wheel_tire" />
@@ -441,9 +437,7 @@
             <origin rpy="1.5707963267948966 0 0" xyz="0 0.047 0" />
         </joint>
 
-        <link name="left_wheel_center">
-            <xacro:virtual_link_inertia />
-        </link>
+        <xacro:virtual_link name="left_wheel_center" />
 
         <joint name="left_wheel_center_fix" type="fixed">
             <parent link="left_wheel_tire" />
diff --git a/xacro/right_leg.xacro b/xacro/right_leg.xacro
index e2bc4fb..6ab1a61 100644
--- a/xacro/right_leg.xacro
+++ b/xacro/right_leg.xacro
@@ -331,9 +331,7 @@
             <origin rpy="3.141592653589793 0 0" xyz="0 0 -0.0015" />
         </joint>
 
-        <link name="right_anchor">
-            <xacro:virtual_link_inertia />
-        </link>
+        <xacro:virtual_link name="right_anchor" />
 
         <joint name="right_anchor_fix" type="fixed">
             <parent link="right_ankle_mj5208_stator" />
@@ -429,9 +427,7 @@
             <origin rpy="0 0 0" xyz="0 0 0.0209" />
         </joint>
 
-        <link name="right_contact">
-            <xacro:virtual_link_inertia />
-        </link>
+        <xacro:virtual_link name="right_contact" />
 
         <joint name="right_contact_fix" type="fixed">
             <parent link="right_wheel_tire" />
@@ -441,9 +437,7 @@
             <origin rpy="1.5707963267948966 0 0" xyz="0 0.047 0" />
         </joint>
 
-        <link name="right_wheel_center">
-            <xacro:virtual_link_inertia />
-        </link>
+        <xacro:virtual_link name="right_wheel_center" />
 
         <joint name="right_wheel_center_fix" type="fixed">
             <parent link="right_wheel_tire" />
diff --git a/xacro/torso.xacro b/xacro/torso.xacro
index 628ffb3..0e226f6 100644
--- a/xacro/torso.xacro
+++ b/xacro/torso.xacro
@@ -2,9 +2,7 @@
 <!-- SPDX-License-Identifier: Apache-2.0 -->
 <robot name="upkie" xmlns:xacro="http://ros.org/wiki/xacro">
     <xacro:macro name="torso" params="with_camera with_handle">
-        <link name="base">
-            <xacro:virtual_link_inertia />
-        </link>
+        <xacro:virtual_link name="base" />
 
         <!-- Torso -->
 
@@ -35,9 +33,7 @@
 
         <!-- IMU -->
 
-        <link name="imu">
-            <xacro:virtual_link_inertia />
-        </link>
+        <xacro:virtual_link name="imu" />
 
         <joint name="imu_fix" type="fixed">
             <!-- not that the origin frame is not translated -->
diff --git a/xacro/upkie.xacro b/xacro/upkie.xacro
index da7189c..f984b07 100644
--- a/xacro/upkie.xacro
+++ b/xacro/upkie.xacro
@@ -15,7 +15,7 @@ Conventions in this file are detailed in:
     <xacro:include filename="xacro/utils/box_inertia.xacro" />
     <xacro:include filename="xacro/utils/cylinder_inertia.xacro" />
     <xacro:include filename="xacro/utils/materials.xacro" />
-    <xacro:include filename="xacro/utils/virtual_link_inertia.xacro" />
+    <xacro:include filename="xacro/utils/virtual_link.xacro" />
 
     <xacro:include filename="xacro/left_leg.xacro" />
     <xacro:include filename="xacro/right_leg.xacro" />
diff --git a/xacro/upkie_camera.xacro b/xacro/upkie_camera.xacro
index 581e6fe..060ce08 100644
--- a/xacro/upkie_camera.xacro
+++ b/xacro/upkie_camera.xacro
@@ -15,7 +15,7 @@ Conventions in this file are detailed in:
     <xacro:include filename="xacro/utils/box_inertia.xacro" />
     <xacro:include filename="xacro/utils/cylinder_inertia.xacro" />
     <xacro:include filename="xacro/utils/materials.xacro" />
-    <xacro:include filename="xacro/utils/virtual_link_inertia.xacro" />
+    <xacro:include filename="xacro/utils/virtual_link.xacro" />
 
     <xacro:include filename="xacro/left_leg.xacro" />
     <xacro:include filename="xacro/right_leg.xacro" />
diff --git a/xacro/utils/virtual_link.xacro b/xacro/utils/virtual_link.xacro
new file mode 100644
index 0000000..e6cf1d5
--- /dev/null
+++ b/xacro/utils/virtual_link.xacro
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!-- SPDX-License-Identifier: Apache-2.0 -->
+<robot name="utils" xmlns:xacro="http://ros.org/wiki/xacro">
+    <xacro:macro name="virtual_link" params="name">
+        <link name="${name}">
+            <!-- virtual link: https://github.com/upkie/upkie_description/wiki/Model-conventions#virtual-links -->
+            <visual>
+                <geometry>
+                    <box size="0 0 0" />
+                </geometry>
+            </visual>
+            <inertial>
+                <mass value="0.001" />
+                <origin rpy="0 0 0" xyz="0 0 0" />
+                <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0" />
+            </inertial>
+        </link>
+    </xacro:macro>
+</robot>
diff --git a/xacro/utils/virtual_link_inertia.xacro b/xacro/utils/virtual_link_inertia.xacro
deleted file mode 100644
index 796c830..0000000
--- a/xacro/utils/virtual_link_inertia.xacro
+++ /dev/null
@@ -1,13 +0,0 @@
-<?xml version="1.0" encoding="utf-8" ?>
-<!-- SPDX-License-Identifier: Apache-2.0 -->
-<robot name="utils" xmlns:xacro="http://ros.org/wiki/xacro">
-    <xacro:macro name="virtual_link_inertia">
-        <!-- virtual link -->
-        <inertial>
-            <!-- mass should not be zero [1] -->
-            <mass value="0.001" />
-            <origin rpy="0 0 0" xyz="0 0 0" />
-            <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0" />
-        </inertial>
-    </xacro:macro>
-</robot>