From: Erik Andresen <erik@vontaene.de>
Date: Sun, 11 Oct 2026 19:35:36 +0000 (+0200)
Subject: urdf fixes
X-Git-Url: https://defiant.homedns.org/gitweb/?a=commitdiff_plain;h=03a16f0e573fad6a330e44fafff967e2ef1d13cc;p=a4wd3.git

urdf fixes
---

diff --git a/urdf/a4wd3.urdf b/urdf/a4wd3.urdf
index cf67184..fe01116 100644
--- a/urdf/a4wd3.urdf
+++ b/urdf/a4wd3.urdf
@@ -3,7 +3,8 @@
      Sources:
        - /home/erik/a4wd3-git/launch/a4wd3_launch.py static transforms (tf_base_scan, tf_base_imu)
        - A4WD3-Wheeled.stp (user CAD, true scale: overall width 437.0 mm matches measurement)
-       - rplidar-a2m4-r1.stl (Slamtec official model; flat-panel lidar, scan axis = mesh Z)
+       - rplidar-a2m4-r1.stl (Slamtec official model; flat-panel lidar, scan axis = mesh Y,
+         window face at mesh y_min; verified by slice analysis, not mesh Z)
      Frame conventions:
        LIVE base_link (as published by hw_node.cpp odom TF): x = forward, y = left, z = up,
        ORIGIN AT WHEELBASE CENTER / AXLE HEIGHT (z=0 at axle plane; ground ~79 mm below,
@@ -33,7 +34,8 @@
     <visual>
       <origin xyz="0 0 0" rpy="0 0 0"/>
       <geometry>
-        <mesh filename="package://a4wd3/meshes/a4wd3_base_rviz.stl"/>
+        <!-- STL stores millimeter coordinates; URDF expects meters -->
+        <mesh filename="package://a4wd3/meshes/a4wd3_base_rviz.stl" scale="0.001 0.001 0.001"/>
       </geometry>
       <material name="chassis_grey">
         <color rgba="0.45 0.45 0.45 1.0"/>
@@ -42,20 +44,29 @@
     <collision>
       <origin xyz="0 0 0" rpy="0 0 0"/>
       <geometry>
-        <mesh filename="package://a4wd3/meshes/a4wd3_base_rviz.stl"/>
+        <mesh filename="package://a4wd3/meshes/a4wd3_base_rviz.stl" scale="0.001 0.001 0.001"/>
       </geometry>
     </collision>
   </link>
 
-  <!-- RP-LIDAR A2M4 (r1), flat panel. Launch tf_base_scan VERBATIM:
-       t=(+0.08125, +0.07425, 0) m, yaw = pi (live base_link frame).
-       => 81.25 mm forward, 74.25 mm left, at axle height; scan plane ~74 mm above axles
-       (~153 mm above floor). Visual origin offset puts the mesh's scan plane
-       (mesh z=+0.1125, body axis at mesh x=-0.006, y=+0.028) onto the laser frame origin. -->
+  <!-- RP-LIDAR A2M4 (r1), flat panel. Launch tf_base_scan VERBATIM for x/y:
+       t=(+0.08125, +0.07425) m, yaw = pi (live base_link frame).
+       => 81.25 mm forward, 74.25 mm left.
+       Z (NOT in launch file, measured 2026-10-11): unit sits 21 mm ABOVE the LOCAL top
+       plate under the lidar (z=+46.0 mm there; the 55.8 mm global max is a raised area
+       elsewhere) -> unit bottom at z=+67.0 mm. After the 180 deg flip the full mesh spans
+       laser z -0.0009..+0.0399 -> joint z = 0.0679 m.
+       MESH GEOMETRY (verified by slice analysis 2026-10-11): the body is a cylinder
+       with its AXIS ALONG MESH Y (slices perp to Y: ~75 mm circles; perp to X/Z: ellipses).
+       Visual transform: Rx(+90 deg) maps mesh +Y -> laser +z, i.e. the unit is FLIPPED
+       180 deg about the laser x axis relative to the raw STL (user confirmed the raw
+       orientation rendered upside down). Origin offset puts the scan-face center
+       (mesh 7.26, 9.15, 75.24 mm) at the laser frame origin. Body then spans laser
+       z -0.0009..+0.0399 m (unit sits ABOVE the frame; bracket arm at unit top). -->
   <joint name="base_to_laser" type="fixed">
     <parent link="base_link"/>
     <child link="laser"/>
-    <origin xyz="0.08125 0.07425 0" rpy="0 0 3.14159"/>
+    <origin xyz="0.08125 0.07425 0.0679" rpy="0 0 3.14159"/>
   </joint>
   <link name="laser">
     <inertial>
@@ -65,22 +76,87 @@
       <inertia ixx="0.0001" ixy="0" ixz="0" iyy="0.0001" iyz="0" izz="0.0002"/>
     </inertial>
     <visual>
-      <origin xyz="0.006 -0.028 -0.1125" rpy="0 0 0"/>
+      <origin xyz="-0.0073 0.0752 -0.0092" rpy="1.5708 0 0"/>
       <geometry>
-        <mesh filename="package://a4wd3/meshes/rplidar_a2m4_decimated.stl"/>
+        <!-- STL stores millimeter coordinates; URDF expects meters -->
+        <mesh filename="package://a4wd3/meshes/rplidar_a2m4_decimated.stl" scale="0.001 0.001 0.001"/>
       </geometry>
       <material name="lidar_black">
         <color rgba="0.1 0.1 0.1 1.0"/>
       </material>
     </visual>
     <collision>
-      <origin xyz="0 0 0" rpy="0 0 0"/>
+      <!-- body only (excl. bracket arm): mesh 79 x 40.8 x 75 mm, axis along mesh Y;
+           center transformed into the laser frame by the same Rx(+90)+offset as the visual -->
+      <origin xyz="-0.0113 0.0002 0.0195" rpy="0 0 0"/>
       <geometry>
-        <box size="0.136 0.041 0.075"/>
+        <box size="0.079 0.075 0.041"/>
       </geometry>
     </collision>
   </link>
 
+  <!-- WHEELS: the chassis mesh EXCLUDES the tire solids (hub + motor housing remain in the
+       mesh and look lumpy without the tire around them). These cylinder visuals restore
+       the true tire outline: dia 158 mm, width 84 mm, centers at (+-110, +-176.5) mm,
+       axle height z=0 (measured from STEP). Visuals only - no collision, so the
+       chassis collision mesh stays the sole collision source. -->
+  <joint name="base_to_wheel_fl" type="fixed">
+    <parent link="base_link"/>
+    <child link="wheel_fl"/>
+    <origin xyz="0.110 0.1765 0" rpy="0 0 0"/>
+  </joint>
+  <link name="wheel_fl">
+    <visual>
+      <origin xyz="0 0 0" rpy="1.5708 0 0"/>
+      <geometry>
+        <cylinder length="0.084" radius="0.079"/>
+      </geometry>
+      <material name="tire_black"><color rgba="0.15 0.15 0.15 1.0"/></material>
+    </visual>
+  </link>
+  <joint name="base_to_wheel_fr" type="fixed">
+    <parent link="base_link"/>
+    <child link="wheel_fr"/>
+    <origin xyz="0.110 -0.1765 0" rpy="0 0 0"/>
+  </joint>
+  <link name="wheel_fr">
+    <visual>
+      <origin xyz="0 0 0" rpy="1.5708 0 0"/>
+      <geometry>
+        <cylinder length="0.084" radius="0.079"/>
+      </geometry>
+      <material name="tire_black"><color rgba="0.15 0.15 0.15 1.0"/></material>
+    </visual>
+  </link>
+  <joint name="base_to_wheel_al" type="fixed">
+    <parent link="base_link"/>
+    <child link="wheel_al"/>
+    <origin xyz="-0.110 0.1765 0" rpy="0 0 0"/>
+  </joint>
+  <link name="wheel_al">
+    <visual>
+      <origin xyz="0 0 0" rpy="1.5708 0 0"/>
+      <geometry>
+        <cylinder length="0.084" radius="0.079"/>
+      </geometry>
+      <material name="tire_black"><color rgba="0.15 0.15 0.15 1.0"/></material>
+    </visual>
+  </link>
+  <joint name="base_to_wheel_ar" type="fixed">
+    <parent link="base_link"/>
+    <child link="wheel_ar"/>
+    <origin xyz="-0.110 -0.1765 0" rpy="0 0 0"/>
+  </joint>
+  <link name="wheel_ar">
+    <visual>
+      <origin xyz="0 0 0" rpy="1.5708 0 0"/>
+      <geometry>
+        <cylinder length="0.084" radius="0.079"/>
+      </geometry>
+      <material name="tire_black"><color rgba="0.15 0.15 0.15 1.0"/></material>
+    </visual>
+  </link>
+
   <!-- BNO085 IMU. Launch tf_base_imu VERBATIM: t=(-0.02, -0.013, 0) m, roll = pi. -->
   <joint name="base_to_imu" type="fixed">
     <parent link="base_link"/>