6.3.2章节描述机器人惯量错误

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报错信息：

tingbo@DESKTOP-NHH5E05:~/chapt6/chapt6_ws$ ros2 launch fishbot_description display_robot.launch.py model:=/home/tingbo/chapt6/chapt6_ws/src/fishbot_description/urdf/fishbot/fishbot.urdf.xacro
[INFO] [launch]: All log files can be found below /home/tingbo/.ros/log/2024-04-19-11-07-25-252392-DESKTOP-NHH5E05-75355
[INFO] [launch]: Default logging verbosity is set to INFO
[ERROR] [launch]: Caught exception in launch (see debug for traceback): executed command failed. Command: xacro /home/tingbo/chapt6/chapt6_ws/src/fishbot_description/urdf/fishbot/fishbot.urdf.xacro
Captured stderr output: error: name 'l' is not defined 
when evaluating expression 'l'
when instantiating macro: box_inertia (/home/tingbo/chapt6/chapt6_ws/install/fishbot_description/share/fishbot_description/urdf/fishbot/common_inertia.xacro)
instantiated from: imu_xacro (/home/tingbo/chapt6/chapt6_ws/install/fishbot_description/share/fishbot_description/urdf/fishbot/sensor/imu.urdf.xacro)
in file: /home/tingbo/chapt6/chapt6_ws/src/fishbot_description/urdf/fishbot/fishbot.urdf.xacro

base.urdf.xacro代码如下：

<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro">
    <xacro:include filename="$(find 
fishbot_description)/urdf/fishbot/common_inertia.xacro"/>
    <xacro:macro name="base_xacro" params ="length radius">
        <link name="base_footprint" />
        <link name="base_link">
            <visual>
                <origin xyz="0.0 0.0 0.0" rpy="0.0 0.0 0.0"/>
                <geometry>
                    <cylinder radius="${length}" length="${length}"/>
                </geometry>
                <material name="white">
                    <color rgba="1.0 1.0 1.0 0.5"/>
                </material>
            </visual>
            <collision>
                <origin xyz="0.0 0.0 0.0" rpy="0.0 0.0 0.0"/>
                <geometry>
                    <cylinder radius="${length}" length="${length}"/>
                </geometry>
                <material name="white">
                    <color rgba="1.0 1.0 1.0 0.5"/>
                </material>
            </collision>
            <xacro:cylinder_inertia m="1.0" r="${radius}" h="${length}"/>
            
        </link>

        <joint name="base_joint" type="fixed">
            <parent link="base_footprint"/>
            <child link="base_link"/>
            <origin xyz=" 0.0 0.0 ${length/2+0.032-0.001}" rpy="0.0 0.0 0.0"/>
            
        </joint>
    </xacro:macro>
    
</robot>

common_inertia.xacro代码如下：

<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro" >
    <xacro:macro name="box_inertia" params="m l w h">
        <inertial>
            <mass value="${m}"/>
            <inertia ixx="${(m/12) * (h*h + l*l)}" ixy="0.0" ixz="0.0" 
iyy="${(m/12) * (w*w + l*l)}" iyz="0.0" izz="${(m/12) * (w*w + h*h)}"/>
        </inertial>
    </xacro:macro>
    
    <xacro:macro name="cylinder_inertia" params="m r h">
        <inertial>
            <mass value="${m}"/>
            <inertia ixx="${(m/12) * (3*r*r + h*h)}" ixy="0.0" ixz="0.0" 
iyy="${(m/12) * (3*r*r + h*h)}" iyz="0.0" izz="${(m/2) * (r*r)}"/>
        </inertial>
    </xacro:macro>
    
    <xacro:macro name="sphere_inertia" params="m r">
        <inertial>
            <mass value="${m}"/>
            <inertia ixx="${(2/5) * m * (r*r)}" ixy="0.0" ixz="0.0" 
iyy="${(2/5) * m * (r*r)}" iyz="0.0" izz="${(2/5) * m * (r*r)}"/>
        </inertial>            
    </xacro:macro>
</robot>

camera.urdf.xacro代码如下：

<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro">
    <xacro:include filename="$(find 
fishbot_description)/urdf/fishbot/common_inertia.xacro"/>
    <xacro:macro name="camera_xacro" params="xyz">
        <!--=========相机模块=========-->
        <link name="camera_link">
            <visual>
                <origin xyz="0.0 0.0 0.0" rpy="0.0 0.0 0.0"/>
                <geometry>
                    <box size="0.02 0.1 0.02"/>
                </geometry>
                <material name="green">
                    <color rgba="0.0 1.0 0.0 0.8"/>
                </material>
            </visual>
            <collision>
                <origin xyz="0.0 0.0 0.0" rpy="0.0 0.0 0.0"/>
                <geometry>
                    <box size="0.02 0.1 0.02"/>
                </geometry>
                <material name="green">
                    <color rgba="0.0 1.0 0.0 0.8"/>
                </material>
            </collision>
            <xacro:box_inertia m="0.05" l="${l}" w="${w}" h="${h}"/>
        </link>

        <joint name="camera_joint" type="fixed">
            <parent link="base_link"/>
            <child link="camera_link"/>
            <origin xyz="${xyz}"/>
        </joint>
    </xacro:macro>
    
</robot>

imu.urdf.xacro代码如下：

<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro">
    <xacro:include filename="$(find 
fishbot_description)/urdf/fishbot/common_inertia.xacro"/>
    <xacro:macro name="imu_xacro" params="xyz">
        <link name="imu_link">
            <visual>
                <origin xyz="0.0 0.0 0.0" rpy="0.0 0.0 0.0"/>
                <geometry>
                    <box size="0.02 0.02 0.02"/>
                </geometry>
                <material name="black">
                    <color rgba="0.0 0.0 0.0 0.8"/>
                </material>
            </visual>
            <collision>
                <origin xyz="0.0 0.0 0.0" rpy="0.0 0.0 0.0"/>
                <geometry>
                    <box size="0.02 0.02 0.02"/>
                </geometry>
                <material name="black">
                    <color rgba="0.0 0.0 0.0 0.8"/>
                </material>
            </collision>
            <xacro:box_inertia m="0.05" l="${l}" w="${w}" h="${h}"/> 
        </link>
        <joint name="imu_joint" type="fixed">
            <parent link="base_link"/>
            <child link="imu_link"/>
            <origin xyz="${xyz}"/>
        </joint>
    </xacro:macro>
</robot>

fishbot.urdf.xacro代码如下：

<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro" name="fishbot">
    <xacro:include filename="$(find fishbot_description)/urdf/fishbot/base.urdf.xacro" />
    <!--传感器组件-->
    <xacro:include filename="$(find fishbot_description)/urdf/fishbot/sensor/imu.urdf.xacro" />
    <xacro:include filename="$(find fishbot_description)/urdf/fishbot/sensor/laser.urdf.xacro" />
    <xacro:include filename="$(find fishbot_description)/urdf/fishbot/sensor/camera.urdf.xacro" />
    <xacro:base_xacro length="0.12" radius="0.1" />
    <!--传感器-->
    <xacro:imu_xacro xyz="0.0 0.0 0.02" />
    <xacro:laser_xacro xyz="0.0 0.0 0.1" />
    <xacro:camera_xacro xyz="0.1 0.0 0.075" />
    <!--执行器组件-->
    <xacro:include filename="$(find fishbot_description)/urdf/fishbot/actuator/wheel.urdf.xacro" />
    <xacro:include filename="$(find fishbot_description)/urdf/fishbot/actuator/caster.urdf.xacro" />
    <!--执行器主动轮+从动轮-->
    <xacro:wheel_xacro wheel_name="left" xyz="0.0 0.1 -0.06" />
    <xacro:wheel_xacro wheel_name="right" xyz="0.0 -0.1 -0.06" />
    <xacro:caster_xacro caster_name="front" xyz="0.08 0.0 -0.076" />
    <xacro:caster_xacro caster_name="back" xyz="-0.08 0.0 -0.076" />
</robot>

小鱼

@43996173 在 6.3.2章节描述机器人惯量错误中说：

<xacro:box_inertia m="0.05" l="${l}" w="${w}" h="${h}"/>
</link>

在使用的时候要给具体的值，比如imu，lwh 就给0.02 0.02 0.02 ，写成参数就要从外部传入

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@小鱼
ok，好了