Where on the robot is body_link?

banana_bread · August 2, 2023, 9:11am

I’m trying to get the transformation matrix between Husarion logo on the front of the robot and the odom_link. From what I understand the odom_link is defined to be the body_link when the ekf turns on. Where exactly on the robot is the body_link in meters?

JanBrzyk · August 2, 2023, 10:12am

Hello @banana_bread and welcome to the Husarion Community!

I recommend analyzing this file from the rosbot_ros repository:

github.com

husarion/rosbot_ros/blob/humble/rosbot_description/urdf/body.urdf.xacro

<?xml version="1.0" encoding="utf-8"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro">
  <!-- body defining macro -->
  <xacro:macro name="body" params="wheel_radius mecanum use_gpu">
    <xacro:include filename="$(find rosbot_description)/urdf/components/vl53lox.urdf.xacro" ns="range_sensor" />

    <link name="base_link" />

    <joint name="base_to_body_joint" type="fixed">
      <origin xyz="0.0 0.0 ${wheel_radius}" rpy="0.0 0.0 0.0" />
      <parent link="base_link" />
      <child link="body_link" />
    </joint>

    <link name="body_link">
      <visual>
        <geometry>
          <mesh filename="file://$(find rosbot_description)/meshes/body.stl" scale="0.001 0.001 0.001" />
        </geometry>
        <origin xyz="0.0 0.0 -0.0173" rpy="${pi/2} 0.0 ${pi/2}" />

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Best regards
Jan Brzyk