Robots/NXT/cturtle

Contents

Installation instructions

Installation instructions

These instructions cover installing NXT-related software for ROS C Turtle on an Ubuntu machine (9.10 or newer). For more an overview of NXT software and ROS, please see the NXT software overview. These instructions will not work on Windows.

Configure your computer

Before your computer can talk to the NXT brick you need to set your udev rules.

Start by adding the lego group:

```
sudo groupadd lego
```

Then add yourself to that group:

```
sudo usermod -a -G lego <username>
```

Now create a udev rules file for the lego group that you just created.

echo "BUS==\"usb\", ATTRS{idVendor}==\"0694\", GROUP=\"lego\", MODE=\"0660\"" > /tmp/70-lego.rules && sudo mv /tmp/70-lego.rules /etc/udev/rules.d/70-lego.rules

On ubuntu 12.04 use

echo "SUBSYSTEM==\"usb\", ATTRS{idVendor}==\"0694\", GROUP=\"lego\", MODE=\"0660\"" > /tmp/70-lego.rules && sudo mv /tmp/70-lego.rules /etc/udev/rules.d/70-lego.rules

Now restart udev:

```
sudo restart udev
```

Now log out and log back in to finish.

Info: these instructions are derived from the NXT-Python page

Install ROS

Before you can install the NXT-ROS bindings, you need to install ROS. This is very easy on Ubuntu systems, just follow the instructions on this page

Install NXT-ROS

Once you finished installing ROS, you can install the NXT-ROS bindings:

First get the rosinstall tool and mercurial:

sudo apt-get install python-setuptools
sudo easy_install -U rosinstall
sudo apt-get install mercurial

Then download and build the NXT-ROS bindings:

rosinstall ~/nxtros /opt/ros/cturtle "http://wiki/nxt/Installation?action=AttachFile&do=get&target=nxt-0.1.0.rosinstall"
. ~/nxtros/setup.sh
rosmake nxt nxt_apps nxt_robots --rosdep-install

NXT developers use this checkout command /devel

If you open new terminals you will either need to type the following:

. ~/nxtros/setup.sh

or add that line to your .bashrc file.

Try it

Before diving into nxt and ROS make sure that you can communicate with your brick by running a simple test.

Start a roscore in a new terminal:

```
roscore 
```

Then run one or both of the following tests in another terminal:

Touch sensor, plug the touch sensor into PORT1 and run the following code. It will display the current state of the touch sensor.

```
rosrun nxt_python touch_sensor_test.py 
```

Color sensor,plug the color sensor into PORT1 and run the following code. It will cycle the LED colors and display the intensity then the color detected.

```
rosrun nxt_python color_sensor_test.py 
```

Your computer is not configured correctly or the brick is off if you see:

Traceback (most recent call last):
  File "/u/mwise/external_repos/foote-ros-pkg/nxt/trunk/nxt_python/sensor_tests/touch_sensor_test.py", line 21, in <module>
    sock = nxt.locator.find_one_brick()
  File "/u/mwise/external_repos/foote-ros-pkg/nxt/trunk/nxt_python/src/nxt/locator.py", line 57, in find_one_brick
    raise BrickNotFoundError
nxt.locator.BrickNotFoundError

Next step

Now check out our starter robots in nxt_robots.

Or, find tutorials and more documentation in nxt.