前言

闲来无事，手上又没有可玩的机器人，就简单打个仿真玩一下

安装软件

我这里使用的docker镜像，基于ubuntu18.04 + ros-melodic的
https://hub.docker.com/repository/docker/vell001/ubt18.04_ros_xrdp

# 安装ROS Melodic
sudo apt install ros-melodic-desktop-full

# 安装Gazebo插件和键盘控制包
sudo apt install ros-melodic-gazebo-ros-pkgs ros-melodic-teleop-twist-keyboard

创建工作空间

mkdir -p ~/vellbot_ws/src && cd ~/vellbot_ws
catkin_make
source devel/setup.bash

创建机器人模型

我这里非常简单，使用两轮差速控制，有两个差速轮，和一个万向支撑轮

对应xacro文件如下：

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

    <!-- Defining the colors used in this robot -->
    <material name="Black">
        <color rgba="0 0 0 1"/>
    </material>

    <material name="Blue">
        <color rgba="0 0 1 1"/>
    </material>

    <link name="base_link">
        <visual>
            <origin xyz="0 0 0.1" rpy="0 0 0"/>
            <geometry>
                <box size="0.4 0.6 0.1"/>
            </geometry>
            <material name="Blue"/>
        </visual>
        <collision>
            <origin xyz="0 0 0.1" rpy="0 0 0"/>
            <geometry>
                <box size="0.4 0.6 0.1"/>
            </geometry>
        </collision>
        <inertial>
            <mass value="5.0"/>
            <inertia ixx="0.1" ixy="0" ixz="0" iyy="0.1" iyz="0" izz="0.2"/>
        </inertial>
    </link>

    <xacro:macro name="wheel" params="name radius:=0.05 width:=0.02">
        <link name="${name}">
            <visual>
                <origin xyz="0 0 0" rpy="0 1.5708 0"/>
                <geometry>
                    <cylinder radius="${radius}" length="${width}"/>
                </geometry>
                <material name="Black"/>
            </visual>
            <collision>
                <origin xyz="0 0 0" rpy="0 1.5708 0"/>
                <geometry>
                    <cylinder radius="${radius}" length="${width}"/>
                </geometry>
            </collision>
            <inertial>
                <mass value="0.3"/>
                <inertia ixx="0.0001" ixy="0" ixz="0" iyy="0.0001" iyz="0" izz="0.0002"/>
            </inertial>
        </link>
    </xacro:macro>

    <xacro:macro name="omni_wheel" params="name radius:=0.05">
        <link name="${name}">
            <visual>
                <geometry><sphere radius="${radius}"/></geometry>
                <material name="Black"/>
            </visual>
            <collision>
                <geometry><sphere radius="${radius}"/></geometry>
            </collision>
            <inertial>
                <mass value="0.1"/>
                <inertia ixx="0.00001" ixy="0" ixz="0" iyy="0.00001" iyz="0" izz="0.00001"/>
            </inertial>
        </link>
    </xacro:macro>

    <xacro:wheel name="left_wheel"/>
    <xacro:wheel name="right_wheel"/>
    <xacro:omni_wheel name="caster_wheel"/>

    <joint name="left_wheel_joint" type="continuous">
        <parent link="base_link"/>
        <child link="left_wheel"/>
        <origin xyz="0.15 0.2 0" rpy="0 0 0"/>
        <axis xyz="1 0 0"/>
    </joint>

    <joint name="right_wheel_joint" type="continuous">
        <parent link="base_link"/>
        <child link="right_wheel"/>
        <origin xyz="-0.15 0.2 0" rpy="0 0 0"/>
        <axis xyz="1 0 0"/>
    </joint>

    <joint name="caster_wheel_joint" type="fixed">
        <parent link="base_link"/>
        <child link="caster_wheel"/>
        <origin xyz="0 -0.2 0" rpy="0 0 0"/>
        <axis xyz="0 1 0"/>
    </joint>

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

    <gazebo reference="left_wheel">
        <material>Gazebo/Black</material>
    </gazebo>

    <gazebo reference="right_wheel">
        <material>Gazebo/Black</material>
    </gazebo>

    <gazebo reference="caster_wheel">
        <material>Gazebo/Black</material>
        <mu1>0.1</mu1>
        <mu2>0.05</mu2>
        <kp>1e4</kp>
        <kd>1e3</kd>
    </gazebo>

    <gazebo>
        <plugin name="diff_drive" filename="libgazebo_ros_diff_drive.so">
            <commandTopic>cmd_vel</commandTopic>
            <odometryTopic>odom</odometryTopic>
            <leftJoint>left_wheel_joint</leftJoint>
            <rightJoint>right_wheel_joint</rightJoint>
            <wheelSeparation>0.3</wheelSeparation>
            <wheelDiameter>0.1</wheelDiameter>
        </plugin>
    </gazebo>
</robot>

创建 launch 文件，启动 gazebo 和键盘控制

<launch>
  <!-- 加载机器人模型 -->
  <param name="robot_description" command="$(find xacro)/xacro $(find vellbot)/urdf/vellbot.xacro" />

  <!-- 启动Gazebo -->
  <include file="$(find gazebo_ros)/launch/empty_world.launch">
    <arg name="world_name" value="worlds/empty.world"/>
  </include>

  <!-- 将机器人模型加载到Gazebo -->
  <node name="spawn_urdf" pkg="gazebo_ros" type="spawn_model" 
        args="-param robot_description -urdf -model vellbot" />

  <!-- 启动键盘控制节点 -->
  <node name="teleop" pkg="teleop_twist_keyboard" type="teleop_twist_keyboard.py" output="screen">
    <param name="speed" value="0.5" />    <!-- 线速度（m/s） -->
    <param name="turn" value="1.0" />     <!-- 角速度（rad/s） -->
  </node>
</launch>

按键控制

roslaunch vellbot vellbot_gazebo.launch

正常启动的话，会打印如下键盘控制说明，按如下说明操作即可控制小车运动