Gazebo機器人仿真學習探索筆記機器人模型

Posted 2020-08-15 zhangrelay

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gazebo_models：https://bitbucket.org/osrf/gazebo_models

模型庫下載，可以參考如下命令：

~/Rob_Soft/Gazebo7$ hg clone https://bitbucket.org/osrf/gazebo_models

下載更改目錄下載到指定文件夾中。

模型庫的結構目錄配置等可以參考官方文檔，注意model.sdf。

當然也可以將自己制作的模型上傳到庫中，文檔中也有具體說明。

code$ hg clone https://yourname@bitbucket.org/yourname/gazebo_models
gazebo_models$ hg add mymodel
gazebo_models$ hg add mymodel/model.config
gazebo_models$ hg add mymodel/model.sdf
gazebo_models$ hg commit
gazebo_models$ hg push

SDF模型生成

~/Rob_Soft/Gazebo7$ gedit box.sdf

在其中輸入：

<?xml version='1.0'?>
<sdf version="1.4">
<model name="my_model">
  <pose>0 0 0.5 0 0 0</pose>
  <static>true</static>
    <link name="link">
      <inertial>
        <mass>1.0</mass>
        <inertia> <!-- interias are tricky to compute -->
          <!-- http://answers.gazebosim.org/question/4372/the-inertia-matrix-explained/ -->
          <ixx>0.083</ixx>       <!-- for a box: ixx = 0.083 * mass * (y*y + z*z) -->
          <ixy>0.0</ixy>         <!-- for a box: ixy = 0 -->
          <ixz>0.0</ixz>         <!-- for a box: ixz = 0 -->
          <iyy>0.083</iyy>       <!-- for a box: iyy = 0.083 * mass * (x*x + z*z) -->
          <iyz>0.0</iyz>         <!-- for a box: iyz = 0 -->
          <izz>0.083</izz>       <!-- for a box: izz = 0.083 * mass * (x*x + y*y) -->
        </inertia>
      </inertial>
      <collision name="collision">
        <geometry>
          <box>
            <size>1 1 1</size>
          </box>
        </geometry>
      </collision>
      <visual name="visual">
        <geometry>
          <box>
            <size>1 1 1</size>
          </box>
        </geometry>
      </visual>
    </link>
  </model>
</sdf>

然後保存即可。

機器人模型

1 設置模型目錄

~/.gazebo/models$ mkdir -p ~/.gazebo/models/my_robot
~/.gazebo/models$ gedit ~/.gazebo/models/my_robot/model.config

<?xml version="1.0"?>
<model>
  <name>My Robot</name>
  <version>1.0</version>
  <sdf version='1.4'>model.sdf</sdf>

  <author>
   <name>My Name</name>
   <email>me@my.email</email>
  </author>

  <description>
    My awesome robot.
  </description>
</model>

機器人模型sdf：

~/.gazebo/models$ gedit ~/.gazebo/models/my_robot/model.sdf

加入如下內容：

<?xml version='1.0'?>
<sdf version='1.4'>
  <model name="my_robot">
  <static>false</static>
          <link name='chassis'>
            <pose>0 0 .1 0 0 0</pose>
            <collision name='collision'>
              <geometry>
                <box>
                  <size>.4 .2 .1</size>
                </box>
              </geometry>
            </collision>

            <visual name='visual'>
              <geometry>
                <box>
                  <size>.4 .2 .1</size>
                </box>
              </geometry>
            </visual>

          <collision name='caster_collision'>
            <pose>-0.15 0 -0.05 0 0 0</pose>
            <geometry>
                <sphere>
                <radius>.05</radius>
              </sphere>
            </geometry>

            <surface>
              <friction>
                <ode>
                  <mu>0</mu>
                  <mu2>0</mu2>
                  <slip1>1.0</slip1>
                  <slip2>1.0</slip2>
                </ode>
              </friction>
            </surface>
          </collision>

          <visual name='caster_visual'>
            <pose>-0.15 0 -0.05 0 0 0</pose>
            <geometry>
              <sphere>
                <radius>.05</radius>
              </sphere>
            </geometry>
          </visual>
          </link>

      <link name="left_wheel">
        <pose>0.1 0.13 0.1 0 1.5707 1.5707</pose>
        <collision name="collision">
          <geometry>
            <cylinder>
              <radius>.1</radius>
              <length>.05</length>
            </cylinder>
          </geometry>
        </collision>
        <visual name="visual">
          <geometry>
            <cylinder>
              <radius>.1</radius>
              <length>.05</length>
            </cylinder>
          </geometry>
        </visual>
      </link>

      <link name="right_wheel">
        <pose>0.1 -0.13 0.1 0 1.5707 1.5707</pose>
        <collision name="collision">
          <geometry>
            <cylinder>
              <radius>.1</radius>
              <length>.05</length>
            </cylinder>
          </geometry>
        </collision>
        <visual name="visual">
          <geometry>
            <cylinder>
              <radius>.1</radius>
              <length>.05</length>
            </cylinder>
          </geometry>
        </visual>
      </link>

      <joint type="revolute" name="left_wheel_hinge">
        <pose>0 0 -0.03 0 0 0</pose>
        <child>left_wheel</child>
        <parent>chassis</parent>
        <axis>
          <xyz>0 1 0</xyz>
        </axis>
      </joint>

      <joint type="revolute" name="right_wheel_hinge">
        <pose>0 0 0.03 0 0 0</pose>
        <child>right_wheel</child>
        <parent>chassis</parent>
        <axis>
          <xyz>0 1 0</xyz>
        </axis>
      </joint>

  </model>
</sdf>

這樣就構建了一個簡單的兩輪差動的移動機器人模型。使用Force工具，可以使其在仿真中運動。

~/.gazebo/models$ gedit ~/.gazebo/models/my_robot/model.sdf

修改其中如下部分：

            <visual name='visual'>
              <geometry>
                <mesh>
                  <uri>model://pioneer2dx/meshes/chassis.dae</uri>
                  <scale>0.9 0.5 0.5</scale>
                </mesh>
              </geometry>
            </visual>

效果如下圖所示：

添加傳感器

    <include>
      <uri>model://hokuyo</uri>
      <pose>0.2 0 0.2 0 0 0</pose>
    </include>
    <joint name="hokuyo_joint" type="revolute">
      <child>hokuyo::link</child>
      <parent>chassis</parent>
      <axis>
        <xyz>0 0 1</xyz>
        <limit>
          <upper>0</upper>
          <lower>0</lower>
        </limit>
      </axis>
    </joint>

當然也可以參考官方教程在機器人上添加其他對象。具體參考附件。

附件-官网教程汇总-构建机器人模型-Build a Robot

Model structure and requirements

Overview

Gazebo is able to dynamically load models into simulation either programmatically or through the GUI. Models exist on your computer, after they have been downloaded or created by you. This tutorial describes Gazebo's model directory structure, and the necessary files within a model directory.

Models in Gazebo define a physical entity with dynamic, kinematic, andvisual properties. In addition, a model may have one or more plugins, whichaffect the model's behavior. A model can represent anything from a simpleshape to a complex robot; even the ground is a model.

Gazebo relies on a database to store and maintain models available for usewithin simulation. The model database is a community-supported resource, soplease upload and maintain models that you create and use.

The Model Database Repository

The model database is a bitbucket repository found here.

You can clone the repository using:

    hg clone https://bitbucket.org/osrf/gazebo_models

Model Database Structure

A model database must abide by a specific directory and file structure. Theroot of a model database contains one directory for each model, and adatabase.config file with information about the model database. Each modeldirectory also has a model.config file that contains meta data about themodel. A model directory also contains the SDF for the model and any materials,meshes, and plugins.

The structure is as follows (in this example the database has only one model called model_1):

Database
- database.config : Meta data about the database. This is now populated automatically from CMakeLists.txt
- model_1 : A directory for model_1
  - model.config : Meta-data about model_1
  - model.sdf : SDF description of the model
  - model.sdf.erb : Ruby embedded SDF model description
  - meshes : A directory for all COLLADA and STL files
  - materials : A directory which should only contain the textures and scripts subdirectories
    - textures : A directory for image files (jpg, png, etc).
    - scripts : A directory for OGRE material scripts
  - plugins: A directory for plugin source and header files

Plugins Directory

This is an optional directory that contains all of the plugins for the model.

Meshes Directory

This is an optional directory that contains all of the COLLADA and/or STL files for the model.

Material Directory

This is an optional directory that contains all of the textures, images, and OGRE scripts for the model. Texture images must be placed in the textures subdirectory, and OGRE script files in the scripts directory.

Database Config

This is the database.config file in the root of the model database. This file contains license information for the models, a name for the database, and a list of all the valid models.

Note: The database.config file is only required for online repositories. A directory full of models on your local computer does not need a database.config file.

The format of this database.config is:

<?xml version='1.0'?>
<database>
  <name>name_of_this_database</name>
  <license>Creative Commons Attribution 3.0 Unported</license>
  <models>
    <uri>file://model_directory</uri>
  </models>
</database>

<name>

The name of the database. This is used by the GUI and other tools.

<license>

The license for the models within the database. We highly recommend theCreative Commons Attribution 3.0 Unported license.

<models>

A listing of all the model URIs within the database.

<uri>
The URI for a model, this should be file://model_directory_name

Model Config

Each model must have a model.config file in the model's root directory that contains meta information about the model.

The format of this model.config is:

<?xml version="1.0"?>

<model>
  <name>My Model Name</name>
  <version>1.0</version>
  <sdf version='1.5'>model.sdf</sdf>

  <author>
    <name>My name</name>
    <email>name@email.address</email>
  </author>

  <description>
    A description of the model
  </description>
</model>

<name> required

Name of the model.

<version> required

Version of this model.

Note: This is not the version of sdf that the model uses. That informationis kept in the model.sdf file.

<sdf> required

The name of a SDF or URDF file that describes this model. The version attribute indicates what SDF version the file uses, and is not required for URDFs. Multiple <sdf> elements may be used in order to support multiple SDF versions.

<author> required
- <name> required
Name of the model author.* <email> required
Email address of the author.
<description> required

Description of the model should include:

What the model is (e.g., robot, table, cup)
What the plugins do (functionality of the model)

<depend> optional

All the dependencies for this model. This is typically other models.

<model> optional
- <uri> required
  URI of the model dependency.
- <version> required
  Version of the model.

Model SDF

Each model requires a model.sdf file that contains the Simulator Description Format of the model. You can find more information on the SDF website.

Model SDF.ERB

Standard SDF file which can contain ruby code embedded. This option is used toprogramatically generate SDF files using Embedded Ruby codetemplates. Please note that the ruby conversion should be done manually (erbmodel.sdf.erb > model.sdf) and the final model.sdf file must be uploadedtogether with the model.sdf.erb (this one only for reference).

Examples of sdf.erb files are available in thegazebo_models repository(some of them use the deprecated suffix .rsdf). An easy ERB file is theflocking.world.erbwhich uses a simple loop.

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