In the first part of our Hokuyo UST-10LX installation article, we made a wiring harness and installed the lidar into RACECAR/J. After connecting the Jetson on the RACECAR to an HDMI monitor, keyboard and mouse we are ready to configure the Hokuyo and test it under ROS. Looky here:
Hokuyo Network Configuration
Once the wiring and installation of the Hokuyo is complete it is time to set the Jetson up to recognize the Hokuyo UST-10LX. A stock UST-10LX is set to an IP address of 192.168.0.10.
In order for the Jetson to recognize the UST-10LX, the Jetson must be on the same ethernet subnet. In the video above, we walk through setting up a static IP connection for talking to the Hokuyo. Because there are many ways that you may configure your network and robot for testing and deployment, that approach is just one example. Typically for deployment you will need to get your hands a little bit dirtier and add something like the following to your configuration in /etc/network/interfaces
For example you might add:
iface eth0 inet static
This is standard Linux talk about how to setup a static IP of 192.168.0.15 on a machine. This is a very large subject, and will not be covered in any depth here. Google is your friend on this one.
Once you have your static IP setup, you should be able to ping the Hokuyo:
$ ping 192.168.0.10
You will receive back the bytes that you sent it. If you do not, make sure that the blue light on the Hokuyo is on (indicating that the device has power). If the light is on, you most likely have network configuration issues.
UST-10LX Under ROS
In an earlier article RACECAR/J Software Install we cover installing the software drivers, ROS and MIT RACECAR ROS packages. Included in the installation is the ROS urg_node, which is a ROS wrapper for the Hokuyo urg_c library. The urg_node allows ROS to communicate with the Hokuyo.
You will need to setup your .bashrc file to reflect the new network configuration, i.e.
Again, these are just example settings and should be changed to match your network.
We can examine the information that the lidar is producing. First open a terminal and start roscore:
Open another terminal. You can list all of the ROS topics:
$ rostopic list
You should see the ‘/scan’ topic. You can then examine the data stream from the lidar:
$ rostopic echo /scan
The data stream displays.
At this point, the Hokuyo is good to go!
In the rest of the video, there is a quick rviz demo. This is more dependent on how you have your robot setup. For the demo, rviz was installed and the LaserScan displayed. The setup for the demo is not covered in this article as you will probably want to run visualizations from a base station connected to the robot over WiFi.
The Hokuyo UST-10LX is a central part of the MIT RACECAR configuration. Installation is a little more challenging than the rest of the build, but with a little patience there should not be any issues.