ROS机器人学习(四)--Gazebo物理仿真环境搭建

本文最后更新于：2022年5月29日 上午

1、配置机器人模型

1. 创建机器人模型文件

在mbot_description功能包的urdf文件夹下新建gazebo文件夹，创建模型文件mbot_base_gazebo.xacro:

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<?xml version="1.0"?>
<robot name="mbot" xmlns:xacro="http://www.ros.org/wiki/xacro">

	<!-- PROPERTY LIST -->
	<xacro:property name="M_PI" value="3.1415926"/>	
    <xacro:property name="base_mass"   value="20" />
	<xacro:property name="base_radius" value="0.16"/>
    <xacro:property name="base_length" value="0.005"/>

    <xacro:property name="wheel_mass"   value="2" />
    <xacro:property name="wheel_radius" value="0.032"/>
    <xacro:property name="wheel_length" value="0.025"/>
	<xacro:property name="wheel_joint_x" value="0.09"/>
    <xacro:property name="wheel_joint_y" value="0.12"/>
    <xacro:property name="wheel_joint_z" value="0.01"/>

	<xacro:property name="caster_mass"    value="0.5" />
	<xacro:property name="caster_radius" value="0.01975"/> <!-- (wheel_radius + wheel_joint_z - base_length/2) / 2 -->
    <xacro:property name="caster_joint_x" value="-0.12"/>

	 <!-- Defining the colors used in this robot -->
    <material name="yellow">
        <color rgba="1 0.4 0 1"/>
    </material>
    <material name="black">
        <color rgba="0 0 0 0.95"/>
    </material>
    <material name="gray">
        <color rgba="0.75 0.75 0.75 1"/>
    </material>
	<material name="white">
		<color rgba="1 1 1 0.9" />
	</material>

	<!-- Macro for inertia matrix -->
    <xacro:macro name="sphere_inertial_matrix" params="m r">
        <inertial>
            <mass value="${m}" />
            <inertia ixx="${2*m*r*r/5}" ixy="0" ixz="0"
                iyy="${2*m*r*r/5}" iyz="0" 
                izz="${2*m*r*r/5}" />
        </inertial>
    </xacro:macro>

    <xacro:macro name="cylinder_inertial_matrix" params="m r h">
        <inertial>
            <mass value="${m}" />
            <inertia ixx="${m*(3*r*r+h*h)/12}" ixy = "0" ixz = "0"
                iyy="${m*(3*r*r+h*h)/12}" iyz = "0"
                izz="${m*r*r/2}" /> 
        </inertial>
    </xacro:macro>

	<!-- Macro for robot wheel -->
    <xacro:macro name="wheel" params="prefix reflect">
        <joint name="${prefix}_wheel_joint" type="continuous">
            <origin xyz="${wheel_joint_x} ${reflect*wheel_joint_y} ${-wheel_joint_z}" rpy="0 0 0"/>
            <parent link="base_link"/>
            <child link="${prefix}_wheel_link"/>
            <axis xyz="0 1 0"/>
        </joint>
        <link name="${prefix}_wheel_link">
            <visual>
                <origin xyz="0 0 0" rpy="${M_PI/2} 0 0" />
                <geometry>
                    <cylinder radius="${wheel_radius}" length = "${wheel_length}"/>
                </geometry>
                <material name="gray" />
            </visual>
			<collision>
                <origin xyz="0 0 0" rpy="${M_PI/2} 0 0" />
                <geometry>
                    <cylinder radius="${wheel_radius}" length = "${wheel_length}"/>
                </geometry>
            </collision>
            <cylinder_inertial_matrix  m="${wheel_mass}" r="${wheel_radius}" h="${wheel_length}" />
        </link>

		<gazebo reference="${prefix}_wheel_link">
            <material>Gazebo/Gray</material>
        </gazebo>

		<!-- Transmission is important to link the joints and the controller -->
        <transmission name="${prefix}_wheel_joint_trans">
            <type>transmission_interface/SimpleTransmission</type>
            <joint name="${prefix}_wheel_joint" >
                <hardwareInterface>hardware_interface/VelocityJointInterface</hardwareInterface>
            </joint>
            <actuator name="${prefix}_wheel_joint_motor">
                <hardwareInterface>hardware_interface/VelocityJointInterface</hardwareInterface>
                <mechanicalReduction>1</mechanicalReduction>
            </actuator>
        </transmission>
    </xacro:macro>



	<xacro:macro name="mbot_base_gazebo">
		<link name="base_footprint">
            <visual>
                <origin xyz="0 0 0" rpy="0 0 0" />
                <geometry>
                    <box size="0.001 0.001 0.001" />
                </geometry>
            </visual>
        </link>
		<gazebo reference="base_footprint">
            <turnGravityOff>false</turnGravityOff>
        </gazebo>
        <joint name="base_footprint_joint" type="fixed">
            <origin xyz="0 0 ${base_length/2 + caster_radius*2}" rpy="0 0 0" />        
            <parent link="base_footprint"/>
            <child link="base_link" />
        </joint>

        <link name="base_link">
            <visual>
                <origin xyz="0 0 0" rpy="0 0 0" />
                <geometry>
                    <cylinder length="${base_length}" radius="${base_radius}"/>
                </geometry>
                <material name="yellow" />
            </visual>
			<collision>
                <origin xyz=" 0 0 0" rpy="0 0 0" />
                <geometry>
                    <cylinder length="${base_length}" radius="${base_radius}"/>
                </geometry>
            </collision>   
            <cylinder_inertial_matrix  m="${base_mass}" r="${base_radius}" h="${base_length}" />
        </link>
		<gazebo reference="base_link">
            <material>Gazebo/Blue</material>
        </gazebo>

		<link name="back_caster_link">
			<visual>
				<origin xyz="0 0 0" rpy="0 0 0" />
				<geometry>
					<sphere radius="${caster_radius}" />
				</geometry>
				<material name="black" />
			</visual>
			<collision>
                <origin xyz="0 0 0" rpy="0 0 0"/>
                <geometry>
                    <sphere radius="${caster_radius}" />
                </geometry>
            </collision>      
            <sphere_inertial_matrix  m="${caster_mass}" r="${caster_radius}" />
		</link>
		<gazebo reference="back_caster_link">
            <material>Gazebo/Black</material>
        </gazebo>
		<joint name="back_caster_joint" type="continuous">
			<origin xyz="${caster_joint_x} 0 ${-(base_length/2 + caster_radius)}" rpy="0 0 0" />
			<parent link="base_link" />
			<child link="back_caster_link" />
			<axis xyz="0 1 0" />
		</joint>

        <wheel prefix="left" reflect="-1"/>
        <wheel prefix="right" reflect="1"/>

		<!-- controller -->
        <gazebo>
            <plugin name="differential_drive_controller" 
                    filename="libgazebo_ros_diff_drive.so">
                <rosDebugLevel>Debug</rosDebugLevel>
                <publishWheelTF>true</publishWheelTF>
                <robotNamespace>/</robotNamespace>
                <publishTf>1</publishTf>
                <publishWheelJointState>true</publishWheelJointState>
                <alwaysOn>true</alwaysOn>
                <updateRate>100.0</updateRate>
                <legacyMode>true</legacyMode>
                <leftJoint>left_wheel_joint</leftJoint>
                <rightJoint>right_wheel_joint</rightJoint>
                <wheelSeparation>${wheel_joint_y*2}</wheelSeparation>
                <wheelDiameter>${2*wheel_radius}</wheelDiameter>
                <broadcastTF>1</broadcastTF>
                <wheelTorque>30</wheelTorque>
                <wheelAcceleration>1.8</wheelAcceleration>
                <commandTopic>cmd_vel</commandTopic>
                <odometryFrame>odom</odometryFrame> 
                <odometryTopic>odom</odometryTopic> 
                <robotBaseFrame>base_footprint</robotBaseFrame>
            </plugin>
        </gazebo> 
    </xacro:macro>

</robot>

2. 模型文件解读

与上一篇文章的xacro模型相比较，主要有以下几点改变：

1）为link添加惯性参数和碰撞属性（以base_link为例）V3powQ.png
2）为link添加gazebo标签（以base_link为例）

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<gazebo reference="base_link">
	<material>Gazebo/Blue</material>
</gazebo>

3）为joint添加传动装置
这里我们给车轮添加传动装置，相当于给车轮添加电机。

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<!-- Transmission is important to link the joints and the controller -->
<transmission name="${prefix}_wheel_joint_trans">
	<type>transmission_interface/SimpleTransmission</type>
	<joint name="${prefix}_wheel_joint" >
		<hardwareInterface>hardware_interface/VelocityJointInterface</hardwareInterface>
	</joint>
	<actuator name="${prefix}_wheel_joint_motor">
		<hardwareInterface>hardware_interface/VelocityJointInterface</hardwareInterface>
		<mechanicalReduction>1</mechanicalReduction>
	</actuator>
</transmission>

4）添加gazebo控制器插件

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<!-- controller -->
<gazebo>
	<plugin name="differential_drive_controller" 
		filename="libgazebo_ros_diff_drive.so">
		<rosDebugLevel>Debug</rosDebugLevel>
		<publishWheelTF>true</publishWheelTF>
		<robotNamespace>/</robotNamespace>
		<publishTf>1</publishTf>
		<publishWheelJointState>true</publishWheelJointState>
		<alwaysOn>true</alwaysOn>
		<updateRate>100.0</updateRate>
		<legacyMode>true</legacyMode>
		<leftJoint>left_wheel_joint</leftJoint>
		<rightJoint>right_wheel_joint</rightJoint>
		<wheelSeparation>${wheel_joint_y*2}</wheelSeparation>
		<wheelDiameter>${2*wheel_radius}</wheelDiameter>
		<broadcastTF>1</broadcastTF>
		<wheelTorque>30</wheelTorque>
		<wheelAcceleration>1.8</wheelAcceleration>
		<commandTopic>cmd_vel</commandTopic>
		<odometryFrame>odom</odometryFrame> 
		<odometryTopic>odom</odometryTopic> 
		<robotBaseFrame>base_footprint</robotBaseFrame>
	</plugin>
</gazebo>

<robotNamespace>：机器人的命名空间。

<leftJoint>和<rightJoint>：左右轮转动的关节joint。

<wheelSeparation>和<wheelDiameter>：机器人模型的相关尺寸，在计算差速参数时需要用到。

<commandTopic>：控制器订阅的速度控制指令，生成全局命名时需要结合<robotNamespace>中设置的命名空间。

<odometryFrame>：里程计数据的参考坐标系，ROS中一般都命名为odom。

3. 在Gazebo中加载机器人模型

1）新建mbot_gazebo功能包：（记得修改packge.xml）

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catkin_create_pkg mbot_gazebo gazebo_plugins gazebo_ros gazebo_ros_control

2）新建launch文件夹，并新建启动文件view_mbot_gazebo_empty_world.launch：

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<launch>

    <!-- 设置launch文件的参数 -->
    <arg name="paused" default="false"/>
    <arg name="use_sim_time" default="true"/>
    <arg name="gui" default="true"/>
    <arg name="headless" default="false"/>
    <arg name="debug" default="false"/>

    <!-- 运行gazebo仿真环境 -->
    <include file="$(find gazebo_ros)/launch/empty_world.launch">
        <arg name="debug" value="$(arg debug)" />
        <arg name="gui" value="$(arg gui)" />
        <arg name="paused" value="$(arg paused)"/>
        <arg name="use_sim_time" value="$(arg use_sim_time)"/>
        <arg name="headless" value="$(arg headless)"/>
    </include>

    <!-- 加载机器人模型描述参数 -->
    <param name="robot_description" command="$(find xacro)/xacro --inorder '$(find mbot_description)/urdf/gazebo/mbot_gazebo.xacro'" /> 

    <!-- 运行joint_state_publisher节点，发布机器人的关节状态  -->
    <node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher" ></node> 

    <!-- 运行robot_state_publisher节点，发布tf  -->
    <node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher"  output="screen" >
        <param name="publish_frequency" type="double" value="50.0" />
    </node>

    <!-- 在gazebo中加载机器人模型-->
    <node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
          args="-urdf -model mbot -param robot_description"/> 

</launch>

3）运行此launch文件即可打开Gazebo加载你的机器模型

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roslaunch mbot_gazebo view_mbot_gazebo_empty_world.launch

V3pqWq.png


### 2、创建仿真环境 在Gazebo创建仿真环境有3种方法：

点击图标或命令行打开运行Gazebo。

第一种方法：直接添加环境模型

V3pOS0.png
添加完后，选择左上角“File->Save world as”保存你的创建的仿真环境。

第二种方法：使用Building Editor

点击Edit 选择Building Editor进入编辑模式，在这里你可以自己画出你想要的仿真环境。V3pbYn.png
创建好环境后，再次点击Edit,选择退出并保存。

3、开始仿真

1）启动仿真环境

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roslaunch mbot_gazebo view_mbot_gazebo_play_ground.launch

2）启动键盘控制

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roslaunch mbot_teleop mbot_teleop.launch

现在你可以控制你的机器人模型在物理仿真中移动了。

V3pjyT.png

想要控制其他的机器人模型，只需要修改launch文件的“加载机器人模型描述参数”，指定你的模型路径即可。

传感器仿真

激光雷达传感器

启动仿真环境

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roslaunch mbot_gazebo view_mbot_with_laser_gazebo.launch

打开rviz添加查看激光雷达仿真

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rosrun rviz rviz

V3pXlV.png

ROS > ROS机器人学习(仿真)
#ROS #ROS仿真
ROS机器人学习(四)--Gazebo物理仿真环境搭建
https://kevinloongc.github.io/posts/64089.html
作者
Kevin Loongc
发布于
2019年4月27日
许可协议