机器人定义与组成
执行机构
驱动系统
传感系统
控制系统
机器人系统构建
执行机构的实现
机器人底盘、电机、舵机
驱动系统的实现
电源子系统，电机驱动子系统、传感器接口
内部传感系统的实现
机器人里程计、惯性测量单元（IMU）
控制系统的实现
外部传感系统的实现
常用传感器的ROS驱动可参考：http://wiki.ros.org/Sensor
URDF机器人建模
- Unified Robot Description Format,统一机器人描述格式
- ROS中非常重要的机器人模型描述格式
<link>
- 描述机器人某个刚体部分的外观和物理属性
- 尺寸、颜色、形状、惯性矩阵、碰撞参数等
- <visual>:描述机器人link部分的外观参数
- <inertial>:描述link的惯性参数
- <collision>:描述link的碰撞属性
<joint>
- 描述机器人关节的运动学和动力学属性
- 包括关节运动的位置和速度限制
- 根据关节运动形式，可以将其分为六种类型：
| 关节类型 | 描述 |
|---|---|
| continuous | 旋转关节，可以围绕单轴无限旋转 |
| revolute | 旋转关节，类似于continuous，但是有旋转的角度极限 |
| prismatic | 滑动关节，沿某一轴线移动的关节，带有位置极限 |
| planar | 平面关节，允许在平面正交方向上平移或旋转 |
| floating | 浮动关节，允许进行平移、旋转运动 |
| fixed | 固定关节，不允许运动的特殊关节 |
- <calibration>:关节的参考位置，用来校准关节的绝对位置
- <dynamics>:描述关节的物理属性，例如阻尼值、物理经摩擦力等，经常在动力学仿真中用到。
- <limit>:描述运动的一些极限值包括关节运动的上下限位置、速度限制、力矩限制等；
- <mimic>:描述该关节与已有关节的关系
- <safety_controller>:描述安全控制器参数
<robot> URDF顶层标签
实践：
1.创建一个机器人建模的功能包
catkin_create_pkg mbot_description urdf xacro //功能包名一般为：机器人名字_description
- urdf:存放机器人模型的URDF或xacro文件
- meshes:防止URDF中引用的模型渲染文件
- launch:保存相关启动文件
- config:保存rviz的配置文件
2.创建一些文件夹
在mobot_description功能包中添加一些文件夹
3.创建launch文件
创建launch文件
文件内容如下：
注意：
- joint_state_publisher:发布每个joint（除fixed类型）的状态，而且可以通过UI界面对joint进行控制
- robot_state_publisher:将机器人各个links、joints之间的关系，通过TF的形式，整理成三维姿态信息发布
4.添加rviz配置文件
添加rviz配置文件
内容如下：
Panels:
- Class: rviz/Displays
Help Height: 78
Name: Displays
Property Tree Widget:
Expanded:
- /Global Options1
- /Status1
- /TF1
Splitter Ratio: 0.5
Tree Height: 541
- Class: rviz/Selection
Name: Selection
- Class: rviz/Tool Properties
Expanded:
- /2D Pose Estimate1
- /2D Nav Goal1
- /Publish Point1
Name: Tool Properties
Splitter Ratio: 0.588679016
- Class: rviz/Views
Expanded:
- /Current View1
Name: Views
Splitter Ratio: 0.5
- Class: rviz/Time
Experimental: false
Name: Time
SyncMode: 0
SyncSource: ""
Visualization Manager:
Class: ""
Displays:
- Alpha: 0.5
Cell Size: 1
Class: rviz/Grid
Color: 160; 160; 164
Enabled: true
Line Style:
Line Width: 0.0299999993
Value: Lines
Name: Grid
Normal Cell Count: 0
Offset:
X: 0
Y: 0
Z: 0
Plane: XY
Plane Cell Count: 10
Reference Frame: <Fixed Frame>
Value: true
- Alpha: 1
Class: rviz/RobotModel
Collision Enabled: false
Enabled: true
Links:
All Links Enabled: true
Expand Joint Details: false
Expand Link Details: false
Expand Tree: false
Link Tree Style: Links in Alphabetic Order
back_caster_link:
Alpha: 1
Show Axes: false
Show Trail: false
Value: true
base_link:
Alpha: 1
Show Axes: false
Show Trail: false
Value: true
camera_link:
Alpha: 1
Show Axes: false
Show Trail: false
Value: true
front_caster_link:
Alpha: 1
Show Axes: false
Show Trail: false
Value: true
left_wheel_link:
Alpha: 1
Show Axes: false
Show Trail: false
Value: true
right_wheel_link:
Alpha: 1
Show Axes: false
Show Trail: false
Value: true
Name: RobotModel
Robot Description: robot_description
TF Prefix: ""
Update Interval: 0
Value: true
Visual Enabled: true
- Class: rviz/TF
Enabled: true
Frame Timeout: 15
Frames:
All Enabled: true
back_caster_link:
Value: true
base_link:
Value: true
camera_link:
Value: true
front_caster_link:
Value: true
left_wheel_link:
Value: true
right_wheel_link:
Value: true
Marker Scale: 0.200000003
Name: TF
Show Arrows: true
Show Axes: true
Show Names: true
Tree:
base_link:
back_caster_link:
{}
camera_link:
{}
front_caster_link:
{}
left_wheel_link:
{}
right_wheel_link:
{}
Update Interval: 0
Value: true
Enabled: true
Global Options:
Background Color: 48; 48; 48
Default Light: true
Fixed Frame: base_link
Frame Rate: 30
Name: root
Tools:
- Class: rviz/Interact
Hide Inactive Objects: true
- Class: rviz/MoveCamera
- Class: rviz/Select
- Class: rviz/FocusCamera
- Class: rviz/Measure
- Class: rviz/SetInitialPose
Topic: /initialpose
- Class: rviz/SetGoal
Topic: /move_base_simple/goal
- Class: rviz/PublishPoint
Single click: true
Topic: /clicked_point
Value: true
Views:
Current:
Class: rviz/Orbit
Distance: 0.791995764
Enable Stereo Rendering:
Stereo Eye Separation: 0.0599999987
Stereo Focal Distance: 1
Swap Stereo Eyes: false
Value: false
Focal Point:
X: -0.00707128178
Y: 0.000214380445
Z: 0.0199916083
Focal Shape Fixed Size: true
Focal Shape Size: 0.0500000007
Invert Z Axis: false
Name: Current View
Near Clip Distance: 0.00999999978
Pitch: 0.305397928
Target Frame: <Fixed Frame>
Value: Orbit (rviz)
Yaw: 0.725397766
Saved: ~
Window Geometry:
Displays:
collapsed: false
Height: 754
Hide Left Dock: false
Hide Right Dock: false
QMainWindow State: 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
Selection:
collapsed: false
Time:
collapsed: false
Tool Properties:
collapsed: false
Views:
collapsed: false
Width: 1191
X: 297
Y: 107
-
URDF机器人建模
5.1 使用圆柱体创建一个车体模型
.urdf文件内容
对应的rviz图像
5.2 使用圆柱体创建左、右侧车轮
<joint name="left_wheel_joint" type="continuous">
<origin xyz="0 0.19 -0.05" rpy="0 0 0"/>
<parent link="base_link"/>
<child link="left_wheel_link"/>
<axis xyz="0 1 0"/>
</joint>
<link name="left_wheel_link">
<visual>
<origin xyz="0 0 0" rpy="1.5707 0 0" />
<geometry>
<cylinder radius="0.06" length = "0.025"/>
</geometry>
<material name="white">
<color rgba="1 1 1 0.9"/>
</material>
</visual>
</link>
<joint name="right_wheel_joint" type="continuous">
<origin xyz="0 -0.19 -0.05" rpy="0 0 0"/>
<parent link="base_link"/>
<child link="right_wheel_link"/>
<axis xyz="0 1 0"/>
</joint>
<link name="right_wheel_link">
<visual>
<origin xyz="0 0 0" rpy="1.5707 0 0" />
<geometry>
<cylinder radius="0.06" length = "0.025"/>
</geometry>
<material name="white">
<color rgba="1 1 1 0.9"/>
</material>
</visual>
</link>
完成后的图像
5.3 使用球体创建前后支撑轮
<joint name="front_caster_joint" type="continuous">
<origin xyz="0.18 0 -0.095" rpy="0 0 0"/>
<parent link="base_link"/>
<child link="front_caster_link"/>
<axis xyz="0 1 0"/>
</joint>
<link name="front_caster_link">
<visual>
<origin xyz="0 0 0" rpy="0 0 0"/>
<geometry>
<sphere radius="0.015" />
</geometry>
<material name="black">
<color rgba="0 0 0 0.95"/>
</material>
</visual>
</link>
<joint name="back_caster_joint" type="continuous">
<origin xyz="-0.18 0 -0.095" rpy="0 0 0"/>
<parent link="base_link"/>
<child link="back_caster_link"/>
<axis xyz="0 1 0"/>
</joint>
<link name="back_caster_link">
<visual>
<origin xyz="0 0 0" rpy="0 0 0"/>
<geometry>
<sphere radius="0.015" />
</geometry>
<material name="black">
<color rgba="0 0 0 0.95"/>
</material>
</visual>
</link>
完成后的图像
5.4 创建传感器——摄像头
重现创建urdf模型文件mbot_with_camera.urdf
<?xml version="1.0" ?>
<robot name="mbot">
<link name="base_link">
<visual>
<origin xyz=" 0 0 0" rpy="0 0 0" />
<geometry>
<cylinder length="0.16" radius="0.20"/>
</geometry>
<material name="yellow">
<color rgba="1 0.4 0 1"/>
</material>
</visual>
</link>
<joint name="left_wheel_joint" type="continuous">
<origin xyz="0 0.19 -0.05" rpy="0 0 0"/>
<parent link="base_link"/>
<child link="left_wheel_link"/>
<axis xyz="0 1 0"/>
</joint>
<link name="left_wheel_link">
<visual>
<origin xyz="0 0 0" rpy="1.5707 0 0" />
<geometry>
<cylinder radius="0.06" length = "0.025"/>
</geometry>
<material name="white">
<color rgba="1 1 1 0.9"/>
</material>
</visual>
</link>
<joint name="right_wheel_joint" type="continuous">
<origin xyz="0 -0.19 -0.05" rpy="0 0 0"/>
<parent link="base_link"/>
<child link="right_wheel_link"/>
<axis xyz="0 1 0"/>
</joint>
<link name="right_wheel_link">
<visual>
<origin xyz="0 0 0" rpy="1.5707 0 0" />
<geometry>
<cylinder radius="0.06" length = "0.025"/>
</geometry>
<material name="white">
<color rgba="1 1 1 0.9"/>
</material>
</visual>
</link>
<joint name="front_caster_joint" type="continuous">
<origin xyz="0.18 0 -0.095" rpy="0 0 0"/>
<parent link="base_link"/>
<child link="front_caster_link"/>
<axis xyz="0 1 0"/>
</joint>
<link name="front_caster_link">
<visual>
<origin xyz="0 0 0" rpy="0 0 0"/>
<geometry>
<sphere radius="0.015" />
</geometry>
<material name="black">
<color rgba="0 0 0 0.95"/>
</material>
</visual>
</link>
<joint name="back_caster_joint" type="continuous">
<origin xyz="-0.18 0 -0.095" rpy="0 0 0"/>
<parent link="base_link"/>
<child link="back_caster_link"/>
<axis xyz="0 1 0"/>
</joint>
<link name="back_caster_link">
<visual>
<origin xyz="0 0 0" rpy="0 0 0"/>
<geometry>
<sphere radius="0.015" />
</geometry>
<material name="black">
<color rgba="0 0 0 0.95"/>
</material>
</visual>
</link>
<link name="camera_link">
<visual>
<origin xyz=" 0 0 0 " rpy="0 0 0" />
<geometry>
<box size="0.03 0.04 0.04" />
</geometry>
<material name="black">
<color rgba="0 0 0 0.95"/>
</material>
</visual>
</link>
<joint name="camera_joint" type="fixed">
<origin xyz="0.17 0 0.10" rpy="0 0 0"/>
<parent link="base_link"/>
<child link="camera_link"/>
</joint>
</robot>
重新创建launch文件display_mbot_with_camera_urdf.launch
<launch>
<param name="robot_description" textfile="$(find mbot_description)/urdf/mbot_with_camera.urdf" />
<!-- 设置GUI参数，显示关节控制插件 -->
<param name="use_gui" value="true"/>
<!-- 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="state_publisher" />
<!-- 运行rviz可视化界面 -->
<node name="rviz" pkg="rviz" type="rviz" args="-d $(find mbot_description)/config/mbot_urdf.rviz" required="true" />
</launch>
完成后图像
5.5 创建传感器——激光雷达
- 编辑urdf文件
- 编辑launch文件
5.6 创建传感器——激光雷达 - 加载meshes文件
- 编辑urdf文件
- 编辑launch文件
6 检查URDF模型整体结构
在urdf文件夹中打开终端，使用指令urdf_to_graphiz mbot_with_kinect.urdf查看待检查的文件。此时在该目录下生成一个pdf文件。
文件内容
