ROS理论与实践——四、机器人仿真
前言
本文是我在18年深蓝学院上课的第二讲内容,过去两年了,我重新整理了下,并结合当时课程布置的作业,在文中给出。本文主要讲关于rviz仿真和gazebo物理仿真。
一、URDF模型优化
上一讲中详细的介绍了机器人URDF模型的建模过程,如不熟悉,可以翻上一讲的内容。
针对URDF模型存在的这些问题:
- 模型冗长,重复内容过多;
- 参数修改麻烦;
- 没有参数计算的功能
对URDF模型进行了优化,即xacro模型,它的两个优点:
- 精简了模型代码(通过创建宏定义、文件包含);
- 提供了可编程的接口(包括常量、变量、数学计算和条件语句)。
1 xacro模型文件使用方法
1.1 常量定义
在xacro文件中对常量进行定义,采用的是property标签,标签里是两个属性,分别是name和value,举例:
<xacro:property name="M_PI" value="3.14159"/>
再比如在原先urdf文件中对于常量定义的修改,代码如下:
<!-- PROPERTY LIST -->
<xacro:property name="M_PI" value="3.1415926"/>
<xacro:property name="base_radius" value="0.20"/>
<xacro:property name="base_length" value="0.16"/>
<xacro:property name="wheel_radius" value="0.06"/>
<xacro:property name="wheel_length" value="0.025"/>
<xacro:property name="wheel_joint_y" value="0.19"/>
<xacro:property name="wheel_joint_z" value="0.05"/>
<xacro:property name="caster_radius" value="0.015"/> <!-- wheel_radius - ( base_length/2 - wheel_joint_z) -->
<xacro:property name="caster_joint_x" value="0.18"/>
常量定义后,使用常量也非常简单,采用${ }的形式,比如:
<origin xyz="0 0 0" rpy="${M_PI/2} 0 0"/>
再比如在urdf模型中对机器人轮模型的优化,代码如下:
<xacro:macro name="wheel" params="prefix reflect">
<joint name="${prefix}_wheel_joint" type="continuous">
<origin xyz="0 ${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>
</link>
</xacro:macro>
1.2 数学计算
<origin xyz="0 ${(motor_length+wheel_length)/2} 0" rpy="0 0 0"/>
注:在xacro文件进行数学计算时,所有的数学运算都会先转换成浮点数进行,以保证运算的精度。
<xacro:macro name="caster" params="prefix reflect">
<joint name="${prefix}_caster_joint" type="continuous">
<origin xyz="${reflect*caster_joint_x} 0 ${-(base_length/2 + caster_radius)}" rpy="0 0 0"/>
<parent link="base_link"/>
<child link="${prefix}_caster_link"/>
<axis xyz="0 1 0"/>
</joint>
<link name="${prefix}_caster_link">
<visual>
<origin xyz="0 0 0" rpy="0 0 0"/>
<geometry>
<sphere radius="${caster_radius}" />
</geometry>
<material name="black" />
</visual>
</link>
</xacro:macro>
1.3 宏定义
类似于C++中函数的使用。
<xacro:macro name="name" params="A B C">
......
</xacro:macro>
宏定义了name后,可进行宏定义的调用,即
<name A="A_value" B="B_value" C="C_value"/>
如上边写轮模型代码中的宏定义,它的宏调用,如下:
<wheel prefix="left" reflect="-1"/>
<wheel prefix="right" reflect="1"/>
1.4 文件包含
类似于C和C++中的include。
在xacro文件中,使用include标签下的filename属性,完成文件包含操作。如:
<xacro:include filename="$(find mbot_description)/urdf/xacro/mbot_base.xacro" />
2 xacro模型文件运行
mbot底盘相当于C++中的main函数,但是还不能直接使用,需要在上层文件中加载,将底盘当作是机器人的零部件。
例如,优化后的xacro模型文件的代码如下:
mbot_base.xacro
<?xml version="1.0"?>
<robot name="mbot" xmlns:xacro="http://www.ros.org/wiki/xacro">
<!-- PROPERTY LIST -->
<xacro:property name="M_PI" value="3.1415926"/>
<xacro:property name="base_radius" value="0.20"/>
<xacro:property name="base_length" value="0.16"/>
<xacro:property name="wheel_radius" value="0.06"/>
<xacro:property name="wheel_length" value="0.025"/>
<xacro:property name="wheel_joint_y" value="0.19"/>
<xacro:property name="wheel_joint_z" value="0.05"/>
<xacro:property name="caster_radius" value="0.015"/> <!-- wheel_radius - ( base_length/2 - wheel_joint_z) -->
<xacro:property name="caster_joint_x" value="0.18"/>
<!-- Defining the colors used in this robot -->
<material name="yellow">
<color rgba="1 0.4 0 1"/>
</material>
<material name="black">
<color rgba="0 0 0 0.95"/>
</material>
<material name="gray">
<color rgba="0.75 0.75 0.75 1"/>
</material>
<!-- Macro for robot wheel -->
<xacro:macro name="wheel" params="prefix reflect">
<joint name="${prefix}_wheel_joint" type="continuous">
<origin xyz="0 ${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>
</link>
</xacro:macro>
<!-- Macro for robot caster -->
<xacro:macro name="caster" params="prefix reflect">
<joint name="${prefix}_caster_joint" type="continuous">
<origin xyz="${reflect*caster_joint_x} 0 ${-(base_length/2 + caster_radius)}" rpy="0 0 0"/>
<parent link="base_link"/>
<child link="${prefix}_caster_link"/>
<axis xyz="0 1 0"/>
</joint>
<link name="${prefix}_caster_link">
<visual>
<origin xyz="0 0 0" rpy="0 0 0"/>
<geometry>
<sphere radius="${caster_radius}" />
</geometry>
<material name="black" />
</visual>
</link>
</xacro:macro>
<xacro:macro name="mbot_base">
<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>
<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="${base_radius}"/>
</geometry>
<material name="yellow" />
</visual>
</link>
<wheel prefix="left" reflect="-1"/>
<wheel prefix="right" reflect="1"/>
<caster prefix="front" reflect="-1"/>
<caster prefix="back" reflect="1"/>
</xacro:macro>
</robot>
上层文件mbot.xacro
<?xml version="1.0"?>
<robot name="arm" xmlns:xacro="http://www.ros.org/wiki/xacro">
<xacro:include filename="$(find mbot_description)/urdf/xacro/mbot_base.xacro" />
<mbot_base/>
</robot>
3 xacro模型显示
主流采用的是直接调用xacro文件解析器,即在launch启动文件中,添加以下代码:
<arg name="model" default="$(find xacro)/xacro --inorder '$(find mbot_description)/urdf/xacro/mbot.xacro'" />
<param name="robot_description" command="$(arg model)" />
其余内容,与之前的launch文件相一致。运行该launch文件即可。
roslaunch mbot_description display_mbot_base_xacro.launch
二、rviz仿真
1 ArbotiX底层控制板
ROS中提供了ArbotiX,是一款控制电机、舵机的硬件控制板,内含一个差速驱动机器人的rviz模拟器。
1.1 安装ArbotiX
本文使用的是ROS版本是Kinetic,因此
git clone https://github.com/vanadiumlabs/arbotix_ros.git
catkin_make
1.2 配置ArbotiX
1.创建launch文件
<launch>
<arg name="model" default="$(find xacro)/xacro --inorder '$(find mbot_description)/urdf/xacro/mbot_with_camera.xacro'" />
<arg name="gui" default="false" />
<param name="robot_description" command="$(arg model)" />
<!-- 设置GUI参数,显示关节控制插件 -->
<param name="use_gui" value="$(arg gui)"/>
<node name="arbotix" pkg="arbotix_python" type="arbotix_driver" output="screen">
<rosparam file="$(find mbot_description)/config/fake_mbot_arbotix.yaml" command="load" />
<param name="sim" value="true"/>
</node>
<!-- 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" />
<!-- 运行robot_state_publisher节点,发布tf -->
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" />
<!-- 运行rviz可视化界面 -->
<node name="rviz" pkg="rviz" type="rviz" args="-d $(find mbot_description)/config/mbot_arbotix.rviz" required="true" />
</launch>
2.创建配置文件
fake_mbot_arbotix.yaml
controllers: {
base_controller: {
type: diff_controller,
base_frame_id: base_footprint,
base_width: 0.26,
ticks_meter: 4100,
Kp: 12,
Kd: 12,
Ki: 0,
Ko: 50,
accel_limit: 1.0
}
}
3.启动仿真器
roslaunch mbot_description arbotix_mbot_with_camera_xacro.launch
4.启动键盘控制
roslaunch mbot_teleop mbot_teleop.launch
2.实例
将自己创建的机器人URDF模型,改写成xacro形式的模型,并在rviz中显示。然后搭建ArbotiX+rviz仿真环境,将完成的机器人模型放置到rviz中,并通过键盘控制运动。
.xacro文件分为三部分:gazebo.urdf.xacro、smartcar.urdf.xacro、smartcar_body.urdf.xacro。
2.1 模型文件
(1)机器人主体smartcar_body.urdf.xacro文件
1 <?xml version="1.0"?>
2 <robot name="smartcar" xmlns:xacro="http://ros.org/wiki/xacro">
3 <property name="M_PI" value="3.14159"/>
4
5 <!-- Macro for SmartCar body. Including Gazebo extensions, but does not include Kinect -->
6 <include filename="$(find smartcar_description)/urdf/gazebo.urdf.xacro"/>
7
8 <property name="base_x" value="0.33" />
9 <property name="base_y" value="0.33" />
10
11 <xacro:macro name="smartcar_body">
12
13
14 <link name="base_link">
15 <inertial> //惯性属性
16 <origin xyz="0 0 0.055"/>
17 <mass value="1.0" />
18 <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
19 </inertial>
20 <visual>
21 <geometry>
22 <box size="0.25 .16 .05"/>
23 </geometry>
24 <origin rpy="0 0 0" xyz="0 0 0.055"/>
25 <material name="blue">
26 <color rgba="0 0 .8 1"/>
27 </material>
28 </visual>
29 <collision> //碰撞属性
30 <origin rpy="0 0 0" xyz="0 0 0.055"/>
31 <geometry>
32 <box size="0.25 .16 .05" />
33 </geometry>
34 </collision>
35 </link>
36
37
38 <link name="left_front_wheel">
39 <inertial>
40 <origin xyz="0.08 0.08 0.025"/>
41 <mass value="0.1" />
42 <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
43 </inertial>
44 <visual>
45 <geometry>
46 <cylinder length=".02" radius="0.025"/>
47 </geometry>
48 <material name="black">
49 <color rgba="0 0 0 1"/>
50 </material>
51 </visual>
52 <collision>
53 <origin rpy="0 1.57075 1.57075" xyz="0.08 0.08 0.025"/>
54 <geometry>
55 <cylinder length=".02" radius="0.025"/>
56 </geometry>
57 </collision>
58 </link>
59
60 <joint name="left_front_wheel_joint" type="continuous">
61 <axis xyz="0 0 1"/>
62 <parent link="base_link"/>
63 <child link="left_front_wheel"/>
64 <origin rpy="0 1.57075 1.57075" xyz="0.08 0.08 0.025"/>
65 <limit effort="100" velocity="100"/>
66 <joint_properties damping="0.0" friction="0.0"/>
67 </joint>
68
69 <link name="right_front_wheel">
70 <inertial>
71 <origin xyz="0.08 -0.08 0.025"/>
72 <mass value="0.1" />
73 <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
74 </inertial>
75 <visual>
76 <geometry>
77 <cylinder length=".02" radius="0.025"/>
78 </geometry>
79 <material name="black">
80 <color rgba="0 0 0 1"/>
81 </material>
82 </visual>
83 <collision>
84 <origin rpy="0 1.57075 1.57075" xyz="0.08 -0.08 0.025"/>
85 <geometry>
86 <cylinder length=".02" radius="0.025"/>
87 </geometry>
88 </collision>
89 </link>
90
91 <joint name="right_front_wheel_joint" type="continuous">
92 <axis xyz="0 0 1"/>
93 <parent link="base_link"/>
94 <child link="right_front_wheel"/>
95 <origin rpy="0 1.57075 1.57075" xyz="0.08 -0.08 0.025"/>
96 <limit effort="100" velocity="100"/>
97 <joint_properties damping="0.0" friction="0.0"/>
98 </joint>
99
100 <link name="left_back_wheel">
101 <inertial>
102 <origin xyz="-0.08 0.08 0.025"/>
103 <mass value="0.1" />
104 <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
105 </inertial>
106 <visual>
107 <geometry>
108 <cylinder length=".02" radius="0.025"/>
109 </geometry>
110 <material name="black">
111 <color rgba="0 0 0 1"/>
112 </material>
113 </visual>
114 <collision>
115 <origin rpy="0 1.57075 1.57075" xyz="-0.08 0.08 0.025"/>
116 <geometry>
117 <cylinder length=".02" radius="0.025"/>
118 </geometry>
119 </collision>
120 </link>
121
122 <joint name="left_back_wheel_joint" type="continuous">
123 <axis xyz="0 0 1"/>
124 <parent link="base_link"/>
125 <child link="left_back_wheel"/>
126 <origin rpy="0 1.57075 1.57075" xyz="-0.08 0.08 0.025"/>
127 <limit effort="100" velocity="100"/>
128 <joint_properties damping="0.0" friction="0.0"/>
129 </joint>
130
131 <link name="right_back_wheel">
132 <inertial>
133 <origin xyz="-0.08 -0.08 0.025"/>
134 <mass value="0.1" />
135 <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
136 </inertial>
137 <visual>
138 <geometry>
139 <cylinder length=".02" radius="0.025"/>
140 </geometry>
141 <material name="black">
142 <color rgba="0 0 0 1"/>
143 </material>
144 </visual>
145 <collision>
146 <origin rpy="0 1.57075 1.57075" xyz="-0.08 -0.08 0.025"/>
147 <geometry>
148 <cylinder length=".02" radius="0.025"/>
149 </geometry>
150 </collision>
151 </link>
152
153
154 <joint name="right_back_wheel_joint" type="continuous">
155 <axis xyz="0 0 1"/>
156 <parent link="base_link"/>
157 <child link="right_back_wheel"/>
158 <origin rpy="0 1.57075 1.57075" xyz="-0.08 -0.08 0.025"/>
159 <limit effort="100" velocity="100"/>
160 <joint_properties damping="0.0" friction="0.0"/>
161 </joint>
162
163 <link name="head">
164 <inertial>
165 <origin xyz="0.08 0 0.08"/>
166 <mass value="0.1" />
167 <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
168 </inertial>
169 <visual>
170 <geometry>
171 <box size=".02 .03 .03"/>
172 </geometry>
173 <material name="white">
174 <color rgba="1 1 1 1"/>
175 </material>
176 </visual>
177 <collision>
178 <origin xyz="0.08 0 0.08"/>
179 <geometry>
180 <cylinder length=".02" radius="0.025"/>
181 </geometry>
182 </collision>
183 </link>
184
185 <joint name="tobox" type="fixed">
186 <parent link="base_link"/>
187 <child link="head"/>
188 <origin xyz="0.08 0 0.08"/>
189 </joint>
190 </xacro:macro>
191
192 </robot>
(2)gazebo属性部分gazebo.urdf.xacro
<?xml version="1.0"?>
<robot xmlns:controller="http://playerstage.sourceforge.net/gazebo/xmlschema/#controller"
xmlns:interface="http://playerstage.sourceforge.net/gazebo/xmlschema/#interface"
xmlns:sensor="http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor"
xmlns:xacro="http://ros.org/wiki/xacro"
name="smartcar_gazebo">
<!-- ASUS Xtion PRO camera for simulation -->
<!-- gazebo_ros_wge100 plugin is in kt2_gazebo_plugins package -->
<xacro:macro name="smartcar_sim">
<gazebo reference="base_link">
<material>Gazebo/Blue</material>
</gazebo>
<gazebo reference="right_front_wheel">
<material>Gazebo/FlatBlack</material>
</gazebo>
<gazebo reference="right_back_wheel">
<material>Gazebo/FlatBlack</material>
</gazebo>
<gazebo reference="left_front_wheel">
<material>Gazebo/FlatBlack</material>
</gazebo>
<gazebo reference="left_back_wheel">
<material>Gazebo/FlatBlack</material>
</gazebo>
<gazebo reference="head">
<material>Gazebo/White</material>
</gazebo>
</xacro:macro>
</robot>
(3)主文件smartcar.urdf.xacro
1 <?xml version="1.0"?>
2
3 <robot name="smartcar"
4 xmlns:xi="http://www.w3.org/2001/XInclude"
5 xmlns:gazebo="http://playerstage.sourceforge.net/gazebo/xmlschema/#gz"
6 xmlns:model="http://playerstage.sourceforge.net/gazebo/xmlschema/#model"
7 xmlns:sensor="http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor"
8 xmlns:body="http://playerstage.sourceforge.net/gazebo/xmlschema/#body"
9 xmlns:geom="http://playerstage.sourceforge.net/gazebo/xmlschema/#geom"
10 xmlns:joint="http://playerstage.sourceforge.net/gazebo/xmlschema/#joint"
11 xmlns:controller="http://playerstage.sourceforge.net/gazebo/xmlschema/#controller"
12
13 xmlns:interface="http://playerstage.sourceforge.net/gazebo/xmlschema/#interface"
14 xmlns:rendering="http://playerstage.sourceforge.net/gazebo/xmlschema/#rendering"
15 xmlns:renderable="http://playerstage.sourceforge.net/gazebo/xmlschema/#renderable"
16
17 xmlns:physics="http://playerstage.sourceforge.net/gazebo/xmlschema/#physics"
18 xmlns:xacro="http://ros.org/wiki/xacro">
19
20 <include filename="$(find smartcar_description)/urdf/smartcar_body.urdf.xacro" />
21
22 <!-- Body of SmartCar, with plates, standoffs and Create (including sim sensors) -->
23 <smartcar_body/>
24
25 <smartcar_sim/>
26
27 </robot>
2.2 设置配置文件
smartcar_arbotix.yaml
1 port: /dev/ttyUSB0
2 baud: 115200
3 rate: 20
4 sync_write: True
5 sync_read: True
6 read_rate: 20
7 write_rate: 20
8
9 controllers: {
10 # Pololu motors: 1856 cpr = 0.3888105m travel = 4773 ticks per meter (empirical: 4100)
11 base_controller: {type: diff_controller, base_frame_id: base_link, base_width: 0.26, ticks_meter: 4100, Kp: 12, Kd: 12, Ki: 0, Ko: 50, accel_limit: 1.0 }
12 }
2.3 mbot_arbotix.rviz文件
使用第三节使用的mbot_arbotix.rviz文件。
2.4 键盘控制文件smartcar_teleop
添加smartcar_teleop.py文件,代码如下:
#!/usr/bin/env python
import roslib; roslib.load_manifest('smartcar_teleop')
import rospy
from geometry_msgs.msg import Twist
from std_msgs.msg import String
class Teleop:
def __init__(self):
pub = rospy.Publisher('cmd_vel', Twist)
rospy.init_node('smartcar_teleop')
rate = rospy.Rate(rospy.get_param('~hz', 1))
self.cmd = None
cmd = Twist()
cmd.linear.x = 0.2
cmd.linear.y = 0
cmd.linear.z = 0
cmd.angular.z = 0
cmd.angular.z = 0
cmd.angular.z = 0.5
self.cmd = cmd
while not rospy.is_shutdown():
str = "hello world %s" % rospy.get_time()
rospy.loginfo(str)
pub.publish(self.cmd)
rate.sleep()
if __name__ == '__main__':Teleop()
2.5 结果展示
实现小车的圆周运动,如下图所示:
三、Gazebo物理仿真环境搭建
1 配置机器人模型
1.1 添加惯性参数和碰撞属性
在上一节xacro模型中,在标签link附上碰撞属性collision和inertial属性,代码如下:
<xacro:macro name="cylinder_inertial_matrix" params="m r h">
<inertial>
<mass value="${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="0 ${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>
1.2 添加gezebo标签
在link标签前添加gazebo标签。
<gazebo reference="${prefix}_caster_link">
<material>Gazebo/Black</material>
</gazebo>
<gazebo reference="${prefix}_caster_link">
<material>Gazebo/Black</material>
</gazebo>
<gazebo reference="base_link">
<material>Gazebo/Blue</material>
</gazebo>
<gazebo reference="base_footprint">
<turnGravityOff>false</turnGravityOff>
</gazebo>
1.3 添加传动装置
给joint添加transmission。
<transmission name="${prefix}_wheel_joint_trans">
<type>transmission_interface/SimpleTransmission</type>
<joint name="${prefix}_wheel_joint" >
<hardwareInterface>hardware_interface/VelocityJointInterface</hardwareInterface>
</joint>
<actuator name="${prefix}_wheel_joint_motor">
<hardwareInterface>hardware_interface/VelocityJointInterface</hardwareInterface>
<mechanicalReduction>1</mechanicalReduction>
</actuator>
</transmission>
1.4 添加控制器插件
<gazebo>
<plugin name="differential_drive_controller"
filename="libgazebo_ros_diff_drive.so">
<rosDebugLevel>Debug</rosDebugLevel>
<publishWheelTF>true</publishWheelTF>
<robotNamespace>/</robotNamespace>
<publishTf>1</publishTf>
<publishWheelJointState>true</publishWheelJointState>
<alwaysOn>true</alwaysOn>
<updateRate>100.0</updateRate>
<legacyMode>true</legacyMode>
<leftJoint>left_wheel_joint</leftJoint>
<rightJoint>right_wheel_joint</rightJoint>
<wheelSeparation>${wheel_joint_y*2}</wheelSeparation>
<wheelDiameter>${2*wheel_radius}</wheelDiameter>
<broadcastTF>1</broadcastTF>
<wheelTorque>30</wheelTorque>
<wheelAcceleration>1.8</wheelAcceleration>
<commandTopic>cmd_vel</commandTopic>
<odometryFrame>odom</odometryFrame>
<odometryTopic>odom</odometryTopic>
<robotBaseFrame>base_footprint</robotBaseFrame>
</plugin>
</gazebo>
2 创建仿真环境
编辑launch文件,在gazebo中加载新建的机器人模型。
view_mbot_gazebo_empty_world.launch
<launch>
<!-- 设置launch文件的参数 -->
<arg name="paused" default="false"/>
<arg name="use_sim_time" default="true"/>
<arg name="gui" default="true"/>
<arg name="headless" default="false"/>
<arg name="debug" default="false"/>
<!-- 运行gazebo仿真环境 -->
<include file="$(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/xacro/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 mrobot -param robot_description"/>
</launch>
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