Tag Archives: laser

Octomap explanierend

In this tutorial, I explain the concept, probabilistic sensor fusion model and the sensor model used in Octomap library.

related publication: OctoMap: An Efficient Probabilistic 3D Mapping Framework Based on Octrees

1)Octamap Volumetric Model

octree storing free (shaded white) and occupied (black) cells. Image is taken from Ref [1]


2)Probabilistic Sensor Fusion Model

3)Sensor Model for Laser Range Data

Image is taken from Ref [1].

 

Autonomous navigation of two wheels differential drive robot in Gazebo

Two wheels differential drive robot (with two caster wheels).
List of installed sensors:
• Velodyne VLP-16.
• Velodyne HDL-32E.
• Hokuyo Laser scanner.
• IMU.
• Microsoft Kinect/Asus Xtion Pro.
• RGB Camera.

You can manually control the robot with Joystick controller for mapping robot environment.
Autonomous navigation is possible by setting goal pose.

 

Assembling Laser scans into PCL point cloud Using Gazebo and ROS

For this work, first I loaded the RRBot in Gazebo and
launched Its joints controller, then I sent a periodic signal to the robot such that the laser scanner mounted on the robot swings.

In the following, I assembled the incoming laser scans with the transformation from tf and created PCL point cloud.

Install the necessary package:

get gazebo_ros_demos from gitHub

Add the path to ROS_PACKAGE_PATH

due to new updates, you need to make some changes in the file rrbot.gazebo, you have to add

this line <legacyModeNS>true</legacyModeNS>

Now run the followings:

you need to install some plugins for rqt. These plug ins will enable you send messages with rqt.

Now launch rqt_gui:

set the second joint value

(/rrbot/joint2_position_controller/command)  into (pi/4)+(1*pi/4)*sin(i/40)*sin(i/40)

and the frequency into 50 Hz, and /rrbot/joint2_position_controller/command)  into 0

Laser Assembler:

Finally, run:

Create a launch file and save the following lines to it and save it under laser_assembler.launch

and run it with roslaunch:

you should get this :

source code at my git hub