Gazebo and URDF model

source code

Catkin package

catkin_create_pkg demo_gazebo rospy
cd demo_gazebo
mkdir launch
mkdir urdf

Minimal urdf file

URDF model link mast have inertia

The inertia matrix explained

<?xml version="1.0"?>
<robot name="robot">
    <link name="base_link">
      <collision>
      <origin xyz="0 0 1" rpy="0 0 0"/>
      <geometry>
        <box size="2 2 2"/>
      </geometry>
    </collision>

    <visual>
      <origin xyz="0 0 1" rpy="0 0 0"/>
      <geometry>
        <box size="2 2 2"/>
      </geometry>
      <material name="orange"/>
    </visual>

    <inertial>
      <origin xyz="0 0 1" rpy="0 0 0"/>
      <mass value="1"/>
      <inertia
        ixx="1.0" ixy="0.0" ixz="0.0"
        iyy="1.0" iyz="0.0"
        izz="1.0"/>
    </inertial>>
    </link>
</robot>

Spawn models

• Using launch file

<launch>
    <param name="robot_description" textfile="$(find demo_gazebo)/urdf/robot_description.urdf" />
    <include file="$(find gazebo_ros)/launch/empty_world.launch"/>
    <node name="spawn_urdf" pkg="gazebo_ros" type="spawn_model"  args="-param robot_description -urdf -model my_robot" />
</launch>

• Using rosrun

rosrun gazebo_ros spawn_model -file `rospack find demo_gazebo`/urdf/robot_description.urdf -urdf -z 1 -model my_robot

Gazebo services

• Check if mode loaded

rosservice call /gazebo/get_world_properties 

sim_time: 1155.376
model_names: [ground_plane, my_robot]
rendering_enabled: True
success: True

• Delete model

rosservice call /gazebo/delete_model "model_name: 'my_robot'" 

success: True
status_message: "DeleteModel: successfully deleted model"

ROS python node

• Call service to insert model into

#! /usr/bin/env python

import rospy
from gazebo_msgs.srv import SpawnModel
from geometry_msgs.msg import Pose


rospy.init_node('insert_object',log_level=rospy.INFO)

initial_pose = Pose()
initial_pose.position.x = 1
initial_pose.position.y = 1
initial_pose.position.z = 1

f = open('/home/user/simulation_ws/src/demo_gazebo/urdf/robot_description.urdf','r')
urdff = f.read()

rospy.wait_for_service('gazebo/spawn_urdf_model')
spawn_model_proxy = rospy.ServiceProxy('gazebo/spawn_urdf_model', SpawnModel)
spawn_model_proxy("some_robot_name", urdff, "robotos_name_space", initial_pose, "world")