Limo Isaac-SIM Simulation Operation Process

1 Env

ubuntu20.04、Omniverse Launcher-1.9.8、Isaac-Sim-(2022.2.1 & 2023.1.1)

2 Start Omniverse

./omniverse-launcher-linux.AppImage

Sign in omniverse account. please register, if you don't have an account.

2. Start Isaac-Sim

1. As shown in the following figure, click on the LIBRARY Isaac-Sim LAUNCH one by one. Download Isaac-Sim if without Isaac-Sim.

2. Then, click on START.

3 Import Limo-URDF Model

# 1. git clone project
git clone https://github.com/agilexrobotics/Limo-Isaac-Sim.git

# 2. unzip meshes.zip and urdf.zip
cd Limo-Isaac-Sim/limo_description
unzip meshes.zip && unzip urdf.zip

2. As shown in the following figure, click on the Isaac-Utils Workflows URDF-Importer one by one.

3. Select correct path of limo urdf and import it.

• Correct Path

./Limo-Isaac-Sim/urdf/limo_base.urdf

If you are importing a mobile robot, you may need to change the following settings

• Uncheck Fix Base Link

• Set the joint drive type to Velocity drive

• Set the Joint Drive Strength to the desired level. Note that this will be imported as the joint’s damping parameter. Joint stiffness are always set to 0 in velocity drive mode.

4. Successfully imported limo urdf as follows.

4 Save Limo Asset

Save as Limo asset for easy import.

5 Limo Simulated Motion

• Detailed configuration referencevideo

6 Driving Limo via ROS messages

Detailed configuration reference

6.1 Building the Graph

• Note:

1. ROS1_Subscribe_Twist setup TopicName: /cmd_vel

2. Differential Controller setup

   • Max Linear Speed: 0.22
   • Wheel Distance: 0.16
   • Wheel Radius: 0.025

3. Articulation Controller To assign the Articulation Controller node’s target to be the Turtlebot. In the property tab, unselect Use Path, and click on Target for the Prim, and find Turtlebot prim in the popup box. Make sure the robot prim you select is also where the Articulation Root API is applied. For some robots, the Articulation Root API is applied to a specific link of the robot and not the parent robot prim(/World/limo/limo_xacro).

4. Constant Token & Make Array To put the names of the wheel joints in an array format, type in the names of the wheel joints inside each of the Constant Token nodes, and feed the array of the names into the Make Array Node. The names of the joints for the Turtlebot are front/rear_right_wheel and front/rear_left_wheel.

6.2 Verifying ROS connections

1. Press Play to start ticking the graph and the physics simulation.
2. Published to /cmd_vel topic to control the robot.

rostopic pub /cmd_vel geometry_msgs/Twist '{linear:  {x: 0.2, y: 0.0, z: 0.0}, angular: {x: 0.0,y: 0.0,z: 0.0}}'

rosrun limo_Isaac_sim limo_bringup.py

7 camera & Lidar

• Detailed camera configuration reference or video

• Detailed lidar configuration reference

• rviz show lidar data

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References

isaacsim

tutorial_advanced_import_urdf

tutorial_ros_drive_turtlebot

tutorial_ros_camera

tutorial_ros_sensors

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