README

What Is This?

This demo creates and runs two ROS 2 nodes individually, namely dummy_laser and dummy_joint_states.

dummy_laser publishes sensor_msgs/msg/LaserScan on a ROS 2 publisher topic, /scan.

dummy_joint_states publishes sensor_msgs/msg/JointState on a ROS 2 publisher topic, /joint_states.

Both dummy_laser and dummy_joint_states are dependencies of dummy_robot_bringup, and are usually expected to be run from the launch file there. Please refer to dummy_robot_bringup.

Build

colcon build --packages-select dummy_sensors

Run

1 - dummy_laser

ros2 run dummy_sensors dummy_laser

# Terminal Output
[INFO] [1658564972.776089023] [dummy_laser]: angle inc: 0.004363
[INFO] [1658564972.776138078] [dummy_laser]: scan size: 1081
[INFO] [1658564972.776148752] [dummy_laser]: scan time increment:       0.000000

2 - dummy_joint_states

ros2 run dummy_sensors dummy_joint_states

Verify

A similar terminal output should be seen after running commands described in the Run section above:

1 - dummy_laser

# Open new terminal.
ros2 topic echo /scan

# Terminal Output
---
header:
  stamp:
    sec: 1658569107
    nanosec: 51491730
  frame_id: single_rrbot_hokuyo_link
angle_min: -2.356194496154785
angle_max: 2.356194496154785
angle_increment: 0.004363323096185923
time_increment: 2.7777778086601757e-05
scan_time: 0.03999999910593033
range_min: 0.0
range_max: 10.0
ranges:
- 0.39602306485176086
- 0.39602306485176086
- 0.39602306485176086
- 0.39602306485176086
- 0.39602306485176086
- 0.39602306485176086
- 0.39602306485176086
- '...'
intensities: []
---

2 - dummy_joint_states

# Open new terminal.
ros2 topic echo /joint_states

# Terminal Output
---
header:
  stamp:
    sec: 1658569569
    nanosec: 414505214
  frame_id: ''
name:
- single_rrbot_joint1
- single_rrbot_joint2
position:
- -0.033653174530243454
- -0.033653174530243454
velocity: []
effort: []
---
header:
  stamp:
    sec: 1658569569
    nanosec: 434418040
  frame_id: ''
name:
- single_rrbot_joint1
- single_rrbot_joint2
position:
- -0.13326191698696957
- -0.13326191698696957
velocity: []
effort: []
---
header:
  stamp:
    sec: 1658569569
    nanosec: 454443902
  frame_id: ''
name:
- single_rrbot_joint1
- single_rrbot_joint2
position:
- -0.2315391504196944
- -0.2315391504196944
velocity: []
effort: []
---
header:
  stamp:
    sec: 1658569569
    nanosec: 474417706
  frame_id: ''
name:
- single_rrbot_joint1
- single_rrbot_joint2
position:
- -0.3275029211980919
- -0.3275029211980919
velocity: []
effort: []
---
header:
  stamp:
    sec: 1658569569
    nanosec: 494442418
  frame_id: ''
name:
- single_rrbot_joint1
- single_rrbot_joint2
position:
- -0.4201943910459491
- -0.4201943910459491
velocity: []
effort: []
---

References

sensor_msgs/msg/LaserScan Message Format: https://github.com/ros2/common_interfaces/blob/rolling/sensor_msgs/msg/LaserScan.msg
sensor_msgs/msg/JointState Message Format: https://github.com/ros2/common_interfaces/blob/rolling/sensor_msgs/msg/JointState.msg