The repository box_bot_description contains the robot model to populate in Gazebo.
# "box_inertia"
# params="mass x y z"
# mass: Mass in Kilograms of the link
# x,y,z: Are the size of each side of the box in each of the axes in meters
<inertia ixx="${mass*(y*y+z*z)/12}" ixy = "0" ixz = "0"
iyy="${mass*(x*x+z*z)/12}" iyz = "0"
izz="${mass*(x*x+z*z)/12}"
/>
# "cylinder_inertia"
# params="mass r l"
# mass: Mass in Kilograms of the link
# r: Radius of the cylinder in meters
# l: Height of the cylinder in meters
# Note: l is parallel to z axis
<inertia ixx="${mass*(3*r*r+l*l)/12}" ixy = "0" ixz = "0"
iyy="${mass*(3*r*r+l*l)/12}" iyz = "0"
izz="${mass*(r*r)/2}" />
# sphere_inertia"
# params="mass r"
# mass: Mass in Kilograms of the link
# r: Radius of the sphere in meters
<inertia
ixx="${2*mass*r*r/5}" ixy = "0" ixz = "0"
iyy="${2*mass*r*r/5}" iyz = "0"
izz="${2*mass*r*r/5}"
/>
source /home/simulations/ros2_sims_ws/install/setup.bash
ros2 run spawn_robot_tools_pkg inertia_wizzard
| Symbol | Definition | Explanation |
|---|---|---|
| mu1 | The static friction coefficient. | It is how much friction there is until the object starts moving in simple terms. |
| mu2 | The dynamic friction coefficient. | It is how much friction there is when the object moves in simple terms. |
These values are calculated through friction tests with elements with the same mass as the links you set these values to. Of course, you should also remember the materials they are made of and so on. However, in reality, it sets them with the values that make the robot behave correctly, not necessarily the real ones.
| Symbol | Definition | Explanation |
|---|---|---|
| kp | This coefficient sets the static contact stiffness. | This determines whether the linked material is closer to marble (rigid, bigger values) or more like rubber (soft material, lower values). |
| kd | This coefficient sets the dynamic contact stiffness. | This determines whether the linked material is closer to marble (rigid, bigger values) or more like rubber (soft material, lower values). It is essentially how much it deforms over a long period, exerting its pressure. |
<gazebo reference="left_wheel">
<kp>1000000000000000000000000000.0</kp>
<kd>1000000000000000000000000000.0</kd>
<mu1>10.0</mu1>
<mu2>10.0</mu2>
<material>Gazebo/Red</material>
</gazebo>
<gazebo reference="right_wheel">
<kp>1000000000000000000000000000.0</kp>
<kd>1000000000000000000000000000.0</kd>
<mu1>10.0</mu1>
<mu2>10.0</mu2>
<material>Gazebo/Green</material>
</gazebo>
<gazebo reference="front_pitch_link">
<kp>1000000000000000000000000000.0</kp>
<kd>1000000000000000000000000000.0</kd>
<mu1>0.5</mu1>
<mu2>0.5</mu2>
<material>Gazebo/Purple</material>
</gazebo>
<gazebo reference="back_pitch_link">
<kp>1000000000000000000000000000.0</kp>
<kd>1000000000000000000000000000.0</kd>
<mu1>0.5</mu1>
<mu2>0.5</mu2>
<material>Gazebo/Yellow</material>
</gazebo>
- In terminal, launch the empty world in Gazebo:
cd ~/ros2_wscolcon buildsource install/setup.bash- `ros2 launch box_bot_gazebo start_world.launch.py
- In another terminal, spawn the robot and publish it's static transforms (Rviz also started but without the
joint_state_publisher_gui, all links but thebase_linkandchassisare missing):cd ~/ros2_ws- (optional)
colcon build source install/setup.bashros2 launch box_bot_gazebo spawn_robot_ros2_physical.launch.xml
For example, see previous heading.
<gazebo>
<plugin name="box_bot_joint_state" filename="libgazebo_ros_joint_state_publisher.so">
<ros>
<remapping>~/out:=joint_states</remapping>
</ros>
<update_rate>30</update_rate>
<joint_name>joint_left_wheel</joint_name>
<joint_name>joint_right_wheel</joint_name>
<joint_name>front_yaw_joint</joint_name>
<joint_name>back_yaw_joint</joint_name>
<joint_name>front_roll_joint</joint_name>
<joint_name>back_roll_joint</joint_name>
<joint_name>front_pitch_joint</joint_name>
<joint_name>back_pitch_joint</joint_name>
</plugin>
</gazebo>
Now Rviz2 shows all the links of the robot:
- Add joint state publisher and differential drive plugins.
- Launch Gazebo and spawn the robot with /robot_description and /joint_states topics.
- Start Gazebo with empty world
cd ~/ros2_ws
colcon build
source install/setup.bash
ros2 launch box_bot_gazebo start_world.launch.py - Spawn the robot and publish to topics
cd ~/ros2_ws
source install/setup.bash
ros2 launch box_bot_gazebo spawn_robot_ros2_control.launch.xml
- Start Gazebo with empty world
- Teleoperate with keyboard.
ros2 run teleop_twist_keyboard teleop_twist_keyboard
ros2_control is a powerful package for robot control in ROS 2.
A small example of using it is shown with a scanner which can be moving "in and out of" the robot body.
[gzserver-1] [INFO] [1721169436.257384484] [box_bot_joint_state]: Going to publish joint [joint_left_wheel][gzserver-1] [INFO] [1721169436.257680481] [box_bot_joint_state]: Going to publish joint [joint_right_wheel][gzserver-1] [INFO] [1721169436.257697876] [box_bot_joint_state]: Going to publish joint [front_yaw_joint][gzserver-1] [INFO] [1721169436.257707970] [box_bot_joint_state]: Going to publish joint [back_yaw_joint][gzserver-1] [INFO] [1721169436.257717722] [box_bot_joint_state]: Going to publish joint [front_roll_joint][gzserver-1] [INFO] [1721169436.257726570] [box_bot_joint_state]: Going to publish joint [back_roll_joint][gzserver-1] [INFO] [1721169436.257735738] [box_bot_joint_state]: Going to publish joint [front_pitch_joint]
[gzserver-1] [INFO] [1721169436.257744701] [box_bot_joint_state]: Going to publish joint [back_pitch_joint]
[gzserver-1] [INFO] [1721169436.527692203] [differential_drive_controller]: Wheel pair 1 separation set to [0.100000m]
[gzserver-1] [INFO] [1721169436.527778761] [differential_drive_controller]: Wheel pair 1 diameter set to [0.070000m]
[gzserver-1] [INFO] [1721169436.528729083] [differential_drive_controller]: Subscribed to [/cmd_vel]
[gzserver-1] [INFO] [1721169436.536845398] [differential_drive_controller]: Advertise odometry on [/odom]
[gzserver-1] [INFO] [1721169436.539397520] [differential_drive_controller]: Publishing odom transforms between [odom] and [base_link]
[gzserver-1] [INFO] [1721169437.462947666] [gazebo_ros2_control]: Loading gazebo_ros2_control plugin
[gzserver-1] [INFO] [1721169437.475064302] [gazebo_ros2_control]: Starting gazebo_ros2_control plugin in namespace: /
[gzserver-1] [INFO] [1721169437.475771653] [gazebo_ros2_control]: Starting gazebo_ros2_control plugin in ros 2 node: gazebo_ros2_control
[gzserver-1] [INFO] [1721169437.475824488] [gazebo_ros2_control]: Loading parameter file /home/user/ros2_ws/install/box_bot_description/share/box_bot_description/config/controller_position.yaml
[gzserver-1]
[gzserver-1] [INFO] [1721169437.479767286] [gazebo_ros2_control]: connected to service!! /robot_state_publisher_node
[gzserver-1] [INFO] [1721169437.481644954] [gazebo_ros2_control]: Recieved urdf from param server, parsing...
[gzserver-1] [INFO] [1721169437.883198988] [gazebo_ros2_control]: Loading joint: laser_scan_link_joint
[gzserver-1] [INFO] [1721169437.883276391] [gazebo_ros2_control]: Command:
[gzserver-1] [INFO] [1721169437.883293695] [gazebo_ros2_control]: position
[gzserver-1] [INFO] [1721169437.883341815] [gazebo_ros2_control]: State:
[gzserver-1] [INFO] [1721169437.883354175] [gazebo_ros2_control]: position
[gzserver-1] [INFO] [1721169437.883384107] [gazebo_ros2_control]: velocity
[gzserver-1] [INFO] [1721169437.883395216] [gazebo_ros2_control]: effort
[gzserver-1] [INFO] [1721169437.883826436] [gazebo_ros2_control]: Loading controller_manager
[gzserver-1] [WARN] [1721169438.186337858] [gazebo_ros2_control]: Desired controller update period (0.01 s) is slower than the gazebo simulation period (0.001 s).
[gzserver-1] [INFO] [1721169438.186613481] [gazebo_ros2_control]: Loaded gazebo_ros2_control.
[gzserver-1] [INFO] [1721169438.378729946] [controller_manager]: Loading controller 'joint_trajectory_controller'
[gzserver-1] [INFO] [1721169438.761729529] [controller_manager]: Loading controller 'joint_state_broadcaster'
[gzserver-1] [INFO] [1721169439.083340941] [controller_manager]: Configuring controller 'joint_trajectory_controller'
[gzserver-1] [INFO] [1721169439.083695418] [joint_trajectory_controller]: Command interfaces are [position] and and state interfaces are [position velocity].
[gzserver-1] [INFO] [1721169439.085478078] [joint_trajectory_controller]: Controller state will be published at 50.00 Hz.
[gzserver-1] [INFO] [1721169439.092730240] [joint_trajectory_controller]: Action status changes will be monitored at 20.00 Hz.
[gzserver-1] [INFO] [1721169439.206844094] [controller_manager]: Configuring controller 'joint_state_broadcaster'
[gzserver-1] [INFO] [1721169439.206992053] [joint_state_broadcaster]: 'joints' or 'interfaces' parameter is empty. All available state interfaces will be published
Server:
[gzserver-1] [INFO] [1721172013.693132450] [joint_trajectory_controller]: Received new action goal
[gzserver-1] [INFO] [1721172013.693291770] [joint_trajectory_controller]: Accepted new action goal
[gzserver-1] [INFO] [1721172014.717216416] [joint_trajectory_controller]: Goal reached, success!
[gzserver-1] [INFO] [1721172047.514888292] [joint_trajectory_controller]: Received new action goal
Client:
user:~/ros2_ws$ ros2 run box_bot_gazebo move_laser.py 0.0
[INFO] [1721172013.727407601] [move_laser_actionclient]: Goal accepted :)
[INFO] [1721172014.722001382] [move_laser_actionclient]: Result: control_msgs.action.FollowJointTrajectory_Result(error_code=0, error_string='')
user:~/ros2_ws$ ros2 run box_bot_gazebo move_laser.py -0.05
[spawner-5] [INFO] [1721169438.763467635] [spawner_joint_trajectory_controller]: Loaded joint_trajectory_controller
[spawner-4] [INFO] [1721169439.084102899] [spawner_joint_state_broadcaster]: Loaded joint_state_broadcaster
[spawner-4] [INFO] [1721169439.228652070] [spawner_joint_state_broadcaster]: Configured and started joint_state_broadcaster
[spawner-5] [INFO] [1721169439.247423035] [spawner_joint_trajectory_controller]: Configured and started joint_trajectory_controller
user:~$ ros2 node info /controller_manager
/controller_manager
Subscribers:
/parameter_events: rcl_interfaces/msg/ParameterEvent
Publishers:
/parameter_events: rcl_interfaces/msg/ParameterEvent
/rosout: rcl_interfaces/msg/Log
Service Servers:
/controller_manager/configure_and_start_controller: controller_manager_msgs/srv/ConfigureStartController
/controller_manager/configure_controller: controller_manager_msgs/srv/ConfigureController
/controller_manager/describe_parameters: rcl_interfaces/srv/DescribeParameters
/controller_manager/get_parameter_types: rcl_interfaces/srv/GetParameterTypes
/controller_manager/get_parameters: rcl_interfaces/srv/GetParameters
/controller_manager/list_controller_types: controller_manager_msgs/srv/ListControllerTypes
/controller_manager/list_controllers: controller_manager_msgs/srv/ListControllers
/controller_manager/list_hardware_interfaces: controller_manager_msgs/srv/ListHardwareInterfaces
/controller_manager/list_parameters: rcl_interfaces/srv/ListParameters
/controller_manager/load_and_configure_controller: controller_manager_msgs/srv/LoadConfigureController
/controller_manager/load_and_start_controller: controller_manager_msgs/srv/LoadStartController
/controller_manager/load_controller: controller_manager_msgs/srv/LoadController
/controller_manager/reload_controller_libraries: controller_manager_msgs/srv/ReloadControllerLibraries
/controller_manager/set_parameters: rcl_interfaces/srv/SetParameters
/controller_manager/set_parameters_atomically: rcl_interfaces/srv/SetParametersAtomically
/controller_manager/switch_controller: controller_manager_msgs/srv/SwitchController
/controller_manager/unload_controller: controller_manager_msgs/srv/UnloadController
Service Clients:
Action Servers:
Action Clients:
####### Node info
####### Service /list_controllers
user:~$ ros2 service call /controller_manager/list_controllers controller_manager_msgs/srv/ListControllers "{}"
requester: making request: controller_manager_msgs.srv.ListControllers_Request()
response:
controller_manager_msgs.srv.ListControllers_Response(controller=[controller_manager_msgs.msg.ControllerState(name='joint_trajectory_controller', state='active', type='joint_trajectory_controller/JointTrajectoryController', claimed_interfaces=['laser_scan_link_joint/position'], required_command_interfaces=['laser_scan_link_joint/position'], required_state_interfaces=['laser_scan_link_joint/position', 'laser_scan_link_joint/velocity']), controller_manager_msgs.msg.ControllerState(name='velocity_controller', state='active', type='velocity_controllers/JointGroupVelocityController', claimed_interfaces=['laser_scan_model_link_joint/velocity'], required_command_interfaces=['laser_scan_model_link_joint/velocity'], required_state_interfaces=[]), controller_manager_msgs.msg.ControllerState(name='joint_state_broadcaster', state='active', type='joint_state_broadcaster/JointStateBroadcaster', claimed_interfaces=[], required_command_interfaces=[], required_state_interfaces=['laser_scan_link_joint/effort', 'laser_scan_link_joint/position', 'laser_scan_link_joint/velocity', 'laser_scan_model_link_joint/effort', 'laser_scan_model_link_joint/position', 'laser_scan_model_link_joint/velocity'])])
user:~/ros2_ws$ ros2 topic pub --once /velocity_controller/commands std_msgs/msg/Float64MultiArray "layout:t:
dim: []
data_offset: 0
data: [-20.0]
"
publisher: beginning loop
publishing #1: std_msgs.msg.Float64MultiArray(layout=std_msgs.msg.MultiArrayLayout(dim=[], data_offset=0), data=[-20.0])
The vertical motion along the z-axis and the rotation around the z-axis can be controlled at the same time, the former with sending goals to an action server and the latter by sending velocity commands.
This sensor is simulated as 360 rays around a circle.
-
Start Gazebo
cd ~/ros2_ws colcon build source install/setup.bash ros2 launch box_bot_gazebo start_world.launch.py -
Spawn the box bot with scanner plugin
cd ~/ros2_ws source install/setup.bash ros2 launch box_bot_gazebo spawn_robot_ros2_sensor.launch.xmlRviz2 Gazebo 
This sensor is simulated with colored points on the reflective surfaces within its declared range.
user:~$ ros2 interface show sensor_msgs/msg/PointCloud
## THIS MESSAGE IS DEPRECATED AS OF FOXY
## Please use sensor_msgs/PointCloud2
# This message holds a collection of 3d points, plus optional additional
# information about each point.
# Time of sensor data acquisition, coordinate frame ID.
std_msgs/Header header
builtin_interfaces/Time stamp
int32 sec
uint32 nanosec
string frame_id
# Array of 3d points. Each Point32 should be interpreted as a 3d point
# in the frame given in the header.
geometry_msgs/Point32[] points
#
#
float32 x
float32 y
float32 z
# Each channel should have the same number of elements as points array,
# and the data in each channel should correspond 1:1 with each point.
# Channel names in common practice are listed in ChannelFloat32.msg.
ChannelFloat32[] channels
#
string name
float32[] values
- Start Gazebo
cd ~/ros2_ws colcon build source install/setup.bash ros2 launch box_bot_gazebo start_world.launch.py - Spawn the box bot with scanner plugin
cd ~/ros2_ws source install/setup.bash ros2 launch box_bot_gazebo spawn_robot_ros2_final.launch.xmlRviz2 Gazebo 
The camera is simulated in a separate window as a fish-eye projection of the world.
| Rviz2 | Gazebo |
|---|---|
 |
 |
This camera is simulated in a separate window as a regular camera.
| Rviz2 | Gazebo |
|---|---|
 |
 |
- Node
user:~$ ros2 node info /imu/bytes_imu
/imu/bytes_imu
Subscribers:
/clock: rosgraph_msgs/msg/Clock
/parameter_events: rcl_interfaces/msg/ParameterEvent
Publishers:
/imu/data: sensor_msgs/msg/Imu
/parameter_events: rcl_interfaces/msg/ParameterEvent
/rosout: rcl_interfaces/msg/Log
Service Servers:
/imu/bytes_imu/describe_parameters: rcl_interfaces/srv/DescribeParameters
/imu/bytes_imu/get_parameter_types: rcl_interfaces/srv/GetParameterTypes
/imu/bytes_imu/get_parameters: rcl_interfaces/srv/GetParameters
/imu/bytes_imu/list_parameters: rcl_interfaces/srv/ListParameters
/imu/bytes_imu/set_parameters: rcl_interfaces/srv/SetParameters
/imu/bytes_imu/set_parameters_atomically: rcl_interfaces/srv/SetParametersAtomically
Service Clients:
Action Servers:
Action Clients:
- Topic
user:~$ ros2 topic info /imu/data --verbose
Type: sensor_msgs/msg/Imu
Publisher count: 1
Node name: bytes_imu
Node namespace: /imu
Topic type: sensor_msgs/msg/Imu
Endpoint type: PUBLISHER
GID: 61.74.10.01.4e.e6.2e.e3.0e.7b.d1.8d.00.00.76.03.00.00.00.00.00.00.00.00
QoS profile:
Reliability: BEST_EFFORT
Durability: VOLATILE
Lifespan: 9223372036854775807 nanoseconds
Deadline: 9223372036854775807 nanoseconds
Liveliness: AUTOMATIC
Liveliness lease duration: 9223372036854775807 nanoseconds
Subscription count: 0
- Interface
user:~$ ros2 interface show sensor_msgs/msg/Imu
# This is a message to hold data from an IMU (Inertial Measurement Unit)
#
# Accelerations should be in m/s^2 (not in g's), and rotational velocity should be in rad/sec
#
# If the covariance of the measurement is known, it should be filled in (if all you know is the
# variance of each measurement, e.g. from the datasheet, just put those along the diagonal)
# A covariance matrix of all zeros will be interpreted as "covariance unknown", and to use the
# data a covariance will have to be assumed or gotten from some other source
#
# If you have no estimate for one of the data elements (e.g. your IMU doesn't produce an
# orientation estimate), please set element 0 of the associated covariance matrix to -1
# If you are interpreting this message, please check for a value of -1 in the first element of each
# covariance matrix, and disregard the associated estimate.
std_msgs/Header header
builtin_interfaces/Time stamp
int32 sec
uint32 nanosec
string frame_id
geometry_msgs/Quaternion orientation
float64 x 0
float64 y 0
float64 z 0
float64 w 1
float64[9] orientation_covariance # Row major about x, y, z axes
geometry_msgs/Vector3 angular_velocity
float64 x
float64 y
float64 z
float64[9] angular_velocity_covariance # Row major about x, y, z axes
geometry_msgs/Vector3 linear_acceleration
float64 x
float64 y
float64 z
float64[9] linear_acceleration_covariance # Row major x, y z
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