Servo - December 2014

Figure 2.

rosrun teleop_twist_keyboard
teleop_twist_keyboard.py

If everything has been done right, you should get instructions on the screen about how to control the robot. The robot should now react to the proper key presses.

This handy program can be used to control the robot while mapping, or any other purpose which involves controlling the Neato robot manually from a distance.

Visualizing the LiDAR Data

Maximize it and change the Topic to /base_scan. As soon as you press Enter, you will see a collection of points on the grid. This is your live laser data visualized (Figure 2).

To read the laser data that is constantly steaming from the Neato, we will need to look at an ROS topic. Topics are specific names that a node uses to pass data to other nodes — one node publishes, the other subscribes, and vice versa. After you have launched the neato_node, you can view all the topics currently open by running the command rostopic list in a new terminal window or tab. You will see a list containing topics such as /base_scan (laser data) and /cmd_vel (motor control).

Of course, this is only the tip of the Rviz iceberg. The program is full of many interesting and exciting features that can be used for even the most complex robots. SV

In this case, we will need the /base_scan topic. With rostopic echo /base_scan, you will be able to view the raw data coming from the laser; these are angles and distances the laser is currently reading. From this data, it is quite hard to figure out what the robot is actually seeing.

Extreme Robot Motor Control

This is why there is a program built into ROS that does exactly that.

Open Rviz by running: rosrun rviz rviz.

MEGAMOTO Plus Shield

Software and plug compatible with our MegaMoto shield

You will see a window open with a 3D grid in the center. In the General Options section in the hierarchy on the left hand side, click on the Fixed Frame drop-down menu. Select /base_laser_link.