12.仿真篇——模拟机械臂URDF过程

1. 创建功能包

catkin_create_pkg marm_description urdf xacro

2. 增加launch启动文件

<launch>
    <!-- 设置机器人模型路径参数 -->
    <param name="robot_description" textfile="$(find marm_description)/urdf/marm.urdf" />
    
    <!-- 运行joint_state_publisher节点，发布机器人的关节状态  -->
    <node name="joint_state_publisher_gui" pkg="joint_state_publisher_gui" type="joint_state_publisher_gui" />
    
    <!-- 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 marm_description)/config/marm_urdf.rviz" required="true" />
</launch>

3. 编写urdf文件

<?xml version="1.0" ?>
<robot name="marm">

<!-- 颜色 -->
	<material name="Black">
		<color rgba="0 0 0 1"/>
	</material>
	<material name="White">
		<color rgba="1 1 1 1"/>
	</material>
	<material name="Blue">
		<color rgba="0 0 1 1"/>
	</material>
	<material name="Red">
		<color rgba="1 0 0 1"/>
	</material>

<!-- base_link -->
	<link name="base_link">
		<visual>
			<origin rpy="0 0 0" xyz="0 0 0"/>
			<geometry>
				<cylinder length="0.04" radius="0.05"/>
			</geometry>
			<material name="White"/>
		</visual>
	</link>
<!-- Link1 -->
	<link name="link1">
		<visual>
			<origin rpy="0 0 0" xyz="0 0 0.05"/>
			<geometry>
				<cylinder length="0.1" radius="0.03"/>
			</geometry>
			<material name="Blue"/>
		</visual>
	</link>

	<joint name="joint1" type="revolute">       <!-- 有上下限位的旋转关节 -->
		<parent link="base_link"/>
		<child link="link1"/>
		<origin rpy="0 0 0" xyz="0 0 0.02"/>
		<axis xyz="0 0 1"/>
		<limit effort="300" lower="-3.14159" upper="3.14159" velocity="1"/> <!-- 力矩、下位、上位、速度 -->
	</joint>

    <!-- Link2 -->
	<link name="link2">
		<visual>
			<origin rpy="0 0 0" xyz="0 0 0.07"/>
			<geometry>
				<cylinder length="0.14" radius="0.03"/>
			</geometry>
			<material name="White"/>
		</visual>
	</link>

	<joint name="joint2" type="revolute">       
		<parent link="link1"/>
		<child link="link2"/>
		<origin rpy="0 0 0" xyz="0 0 0.1"/>
		<axis xyz="0 1 0"/>
		<limit effort="300" lower="-3.14159" upper="3.14159" velocity="1"/> 
	</joint>
    
 <!-- Link3 -->
	<link name="link3">
		<visual>
			<origin rpy="0 0 0" xyz="0 0 0.075"/>
			<geometry>
				<cylinder length="0.15" radius="0.03"/>
			</geometry>
			<material name="Blue"/>
		</visual>
	</link>

	<joint name="joint3" type="revolute">       
		<parent link="link2"/>
		<child link="link3"/>
		<origin rpy="0 0 0" xyz="0 0 0.14"/>
		<axis xyz="0 1 0"/>
		<limit effort="300" lower="-3.14159" upper="3.14159" velocity="1"/> 
	</joint>

     <!-- Link4 -->
	<link name="link4">
		<visual>
			<origin rpy="0 0 0" xyz="0 0 0.03"/>
			<geometry>
				<cylinder length="0.06" radius="0.025"/>
			</geometry>
			<material name="Black"/>
		</visual>
	</link>

	<joint name="joint4" type="revolute">       
		<parent link="link3"/>
		<child link="link4"/>
		<origin rpy="0 0 0" xyz="0 0 0.15"/>
		<axis xyz="0 1 0"/>
		<limit effort="300" lower="-3.14159" upper="3.14159" velocity="1"/> 
	</joint>

     <!-- Link5 -->
	<link name="link5">
		<visual>
			<origin rpy="0 0 0" xyz="0 0 0.03"/>
			<geometry>
				<cylinder length="0.06" radius="0.03"/>
			</geometry>
			<material name="White"/>
		</visual>
	</link>

	<joint name="joint5" type="revolute">       
		<parent link="link4"/>
		<child link="link5"/>
		<origin rpy="0 0 0" xyz="0 0 0.06"/>
		<axis xyz="0 1 0"/>
		<limit effort="300" lower="-3.14159" upper="3.14159" velocity="1"/> 
	</joint>

     <!-- Link6 -->
	<link name="link6">
		<visual>
			<origin rpy="0 0 0" xyz="0 0 0.01"/>
			<geometry>
				<cylinder length="0.02" radius="0.04"/>
			</geometry>
			<material name="White"/>
		</visual>
	</link>

	<joint name="joint6" type="revolute">       
		<parent link="link5"/>
		<child link="link6"/>
		<origin rpy="0 0 0" xyz="0 0 0.06"/>
		<axis xyz="0 0 1"/>
		<limit effort="300" lower="-3.14159" upper="3.14159" velocity="1"/> 
	</joint>

<!-- 夹爪 -->
	<link name="gripper_finger_link1">
		<visual>
			<origin rpy="0 0 0" xyz="0 0 0.03"/>
			<geometry>
				<box size="0.03 0.01 0.06"/>
			</geometry>
			<material name="White"/>
		</visual>
	</link>

	<link name="gripper_finger_link2">
		<visual>
			<origin rpy="0 0 0" xyz="0 0 0.03"/>
			<geometry>
				<box size="0.03 0.01 0.06"/>
			</geometry>
			<material name="White"/>
		</visual>
	</link>

	<joint name="finger_joint1" type="prismatic">
		<parent link="link6"/>
		<child link="gripper_finger_link1"/>
		<origin rpy="0 0 0" xyz="0 -0.03 0.02"/>
		<axis xyz="0 1 0"/>
		<limit effort="100" lower="0" upper="0.06" velocity="0.02"/>
	</joint>

	<joint name="finger_joint2" type="fixed">
		<parent link="link6"/>
		<child link="gripper_finger_link2"/>
		<origin rpy="0 0 0" xyz="0 0.03 0.02"/>
	</joint>

<!-- 法兰盘 -->
	<link name="grasping_frame"/>
	
	<joint name="grasping_frame_joint" type="fixed">
		<parent link="link6"/>
		<child link="grasping_frame"/>
		<origin rpy="0 0 0" xyz="0.06 0 0"/>
	</joint>
</robot>

4. 检查urdf文件的完整性

urdf_to_graphiz mbot.urdf

5. 仿真

roscore
source ./devel/setup.bash
roslaunch marm_description display_marm_urdf.launch