I am a ROS beginner so this might all be a rather basic mistake. But I have a simulation of a drone in Gazebo. I am using controller_manager to spawn controllers for the propellers and a camera. However, robot model in Rviz gives me a lot of no transform link errors because /joint_state topic is not being published.
Here is my control.yaml file
joint_state_controller:
type: joint_state_controller/JointStateController
publish_rate: 50
joint_motor_controller:
type: velocity_controllers/JointGroupVelocityController
joints:
- front_left_prop_joint
- front_right_prop_joint
- back_left_prop_joint
- back_right_prop_joint
camera_joint_position_controller:
type: position_controllers/JointPositionController
joint: camera_joint
drone_base.xacro
<?xml version="1.0" encoding="utf-8"?>
<robot name="drone_description"
xmlns:xacro="http://www.ros.org/wiki/xacro">
<xacro:property name="PI" value="3.14159265359"/>
<xacro:include filename="$(find drone_description)/urdf/drone_macros.xacro" />
<xacro:include filename="$(find drone_description)/urdf/drone_gazebo.xacro" />
<xacro:include filename="$(find drone_description)/urdf/sensors.xacro" />
<!-- DUMMY lINK -->
<link name="dummy_link" />
<!-- LINKS -->
<link name="base_link">
<inertial>
<origin xyz="5.7334E-07 0.026879 0.015324" rpy="0 0 0" />
<mass value="0.38016" />
<inertia ixx="0.00029212" ixy="-1.331E-09" ixz="-3.9126E-08" iyy="0.00040699" iyz="1.6869E-06" izz="0.00015798" />
</inertial>
<visual>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<mesh filename="package://drone_description/meshes/base_link.STL" />
</geometry>
<material name="">
<color rgba="0.69804 0.69804 0.69804 1" />
</material>
</visual>
<collision>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<mesh filename="package://drone_description/meshes/base_link.STL" />
</geometry>
</collision>
</link>
<link name="camera">
<inertial>
<origin xyz="-0.0036143 0.00349 0.00925" rpy="0 0 0" />
<mass value="0.090718" />
<inertia ixx="2.4903E-06" ixy="3.2829E-09" ixz="8.2525E-22" iyy="3.279E-06" iyz="-1.531E-21" izz="2.3388E-06" />
</inertial>
<visual>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<mesh filename="package://drone_description/meshes/camera.STL" />
</geometry>
<material name="">
<color rgba="0.69804 0.69804 0.69804 1" />
</material>
</visual>
<collision>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<mesh filename="package://drone_description/meshes/camera.STL" />
</geometry>
</collision>
</link>
<!-- DUMMY JOINT -->
<joint name="dummy" type="fixed">
<parent link="dummy_link" />
<child link="base_link" />
</joint>
<!-- JOINT -->
<joint name="camera_joint" type="revolute">
<origin xyz="0.00925 0.059965 0.0165" rpy="${PI/2} 0 -${PI/2}" />
<parent link="base_link" />
<child link="camera" />
<axis xyz="0 0 1" />
<limit lower="0" upper="${PI/3}" effort="100" velocity="1" />
</joint>
<transmission name="camera_trans">
<type>transmission_interface/SimpleTransmission</type>
<joint name="camera_joint">
<hardwareInterface>hardware_interface/PositionJointInterface</hardwareInterface>
</joint>
<actuator name="camera_motor">
<mechanicalReduction>1</mechanicalReduction>
<hardwareInterface>hardware_interface/PositionJointInterface</hardwareInterface>
</actuator>
</transmission>
<xacro:prop_link name="front_left_prop" />
<xacro:prop_link name="front_right_prop" />
<xacro:prop_link name="back_left_prop" />
<xacro:prop_link name="back_right_prop" />
<xacro:prop_joint name="front_left_prop" originxyz="-0.092959 0.073449 0.0385" axis="0 0 1"/>
<xacro:prop_joint name="front_right_prop" originxyz="0.092959 0.073449 0.0385" axis="0 0 -1"/>
<xacro:prop_joint name="back_left_prop" originxyz="-0.093338 -0.10988 0.0385" axis="0 0 -1"/>
<xacro:prop_joint name="back_right_prop" originxyz="0.093338 -0.10988 0.0385" axis="0 0 1"/>
<xacro:prop_transmission name="front_left_prop" />
<xacro:prop_transmission name="front_right_prop" />
<xacro:prop_transmission name="back_left_prop" />
<xacro:prop_transmission name="back_right_prop" />
<xacro:propeller_plugin name="front_left_prop" dir="-1" />
<xacro:propeller_plugin name="front_right_prop" dir="1" />
<xacro:propeller_plugin name="back_left_prop" dir="1" />
<xacro:propeller_plugin name="back_right_prop" dir="-1" />
</robot>
drone_macros.xacro
<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro">
<xacro:macro name="prop_link" params="name">
<link name="${name}">
<inertial>
<origin xyz="0 0 0.0089339" rpy="0 0 0" />
<mass value="0.06804" />
<inertia ixx="5.4455E-05" ixy="2.3822E-05" ixz="0" iyy="1.2182E-05" iyz="0" izz="6.5653E-05" />
</inertial>
<visual>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<mesh filename="package://drone_description/meshes/propeller.STL" />
</geometry>
<material name="">
<color rgba="0.69804 0.69804 0.69804 1" />
</material>
</visual>
<collision>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<mesh filename="package://drone_description/meshes/propeller.STL" />
</geometry>
</collision>
</link>
</xacro:macro>
<xacro:macro name="prop_joint" params="name originxyz axis">
<joint name="${name}_joint" type="continuous">
<origin xyz="${originxyz}" rpy="0 0 0" />
<parent link="base_link" />
<child link="${name}" />
<axis xyz="${axis}" />
</joint>
</xacro:macro>
<xacro:macro name="prop_transmission" params="name">
<transmission name="${name}_trans">
<type>transmission_interface/SimpleTransmission</type>
<joint name="${name}_joint">
<hardwareInterface>hardware_interface/VelocityJointInterface</hardwareInterface>
</joint>
<actuator name="${name}_motor">
<mechanicalReduction>1</mechanicalReduction>
<hardwareInterface>hardware_interface/VelocityJointInterface</hardwareInterface>
</actuator>
</transmission>
</xacro:macro>
</robot>
drone_gazebo.xacro
<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro">
<!-- ROS CONTROL -->
<gazebo>
<plugin name="gazebo_ros_control" filename="libgazebo_ros_control.so">
<robotNamespace>/</robotNamespace>
</plugin>
</gazebo>
<!-- LIFT DRAG -->
<xacro:macro name="propeller_plugin" params="name dir">
<gazebo>
<plugin name="${name}_lift" filename="libLiftDragPlugin.so">
<a0>0.0872665</a0>
<cla>0.07365687650517104</cla>
<cda>0.0</cda>
<cma>0.0</cma>
<alpha_stall>1.22173</alpha_stall>
<cla_stall>-0.2</cla_stall>
<cda_stall>1.0</cda_stall>
<cma_stall>0.0</cma_stall>
<cp>0 0.14 0</cp>
<area>0.1</area>
<air_density>1.2041</air_density>
<forward>1 0 0</forward>
<upward>0 0 ${dir}</upward>
<link_name>${name}</link_name>
<control_joint>${name}_joint</control_joint>
</plugin>
</gazebo>
</xacro:macro>
</robot>
gazebo.launch
<launch>
<include file="$(find gazebo_ros)/launch/empty_world.launch" />
<!-- Load URDF to parameter server -->
<param name="robot_description" command="$(find xacro)/xacro $(find drone_description)/urdf/drone_base.xacro" />
<!-- Spawn model in Gazebo -->
<node name="spawn_model" pkg="gazebo_ros" type="spawn_model" args="-urdf -model drone_description -param robot_description" output="screen" />
<rosparam file="$(find drone_description)/config/control.yaml" command="load" />
<node name="controller_spawner" pkg="controller_manager" type="spawner" respawn="false" output="screen" ns="/" args="joint_motor_controller camera_joint_position_controller" />
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" respawn="false" output="screen" />
</launch>
The full package is in a repository here: https://github.com/djangbahevans/ROS-Drone
Originally posted by djangbahevans on ROS Answers with karma: 23 on 2021-02-24
Post score: 1
Original comments
Comment by turtleMaster20 on 2021-02-24:
Can you also post the error messages? Specifically which links are missing.
Comment by djangbahevans on 2021-02-24:
For the dummy_link and base_link, Rviz determines the transforms properly, but for all other links, it says "No transform from [{child_link}] to [base_link]".
Comment by turtleMaster20 on 2021-02-24:
I am guessing the links are not 'jointed' to the dummy link. Try this:
<joint name="dummy" type="fixed"> <parent link="base_link" /> <child link="{child_link}" /> </joint>
Note: In this example it is assumed that the [base_link] and [{child_link}] the same origin, if they have a displacement (or if the relation is not fixed) then change accordingly.
Comment by djangbahevans on 2021-02-24:
There already are joints joining all the other links to the base_link, and they display and work fine in Gazebo. The problem is Rviz visualization isn't working because nothing is publishing on the /joint_states topic.
Comment by turtleMaster20 on 2021-02-24:
Any reason you are not feeding joint_state_controller argument into the the controller_spawner? Can you check once with this argument?
Comment by djangbahevans on 2021-02-24:
That was the mistake. Thanks @turtleMaster20
Comment by turtleMaster20 on 2021-02-25:
Can you tick mark the answer I have posted? Cheers!