A software stack containing tools for using LEGO Mindstorms NXT with ROS.

This branch depends on:
• ROS Fuerte
• Python 2.x
• NXT-Python v2.2.2

Forked from the version for ROS Electric: http://stack-nxt.foote-ros-pkg.googlecode.com/hg

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###Documentation
Installation instructions are in this README file.

The original documentation has more detailed information:
wiki.ros.org/nxt
wiki.ros.org/nxt_robots
wiki.ros.org/nxt_apps
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###Package status

These packages use rosbuild and were tested
with ROS Fuerte on Ubuntu 11.10 and 12.04.

The following features have been tested:

nxt stack:

• nxt_controllers
  Compiles ok, the base_controller has been tested.

• nxt_description
  Working.

• nxt_lxf2urdf
  Compiles ok, un-tested.

• nxt_msgs
  Working.

• nxt_python
  Working.

• nxt_ros
  Working.
  There is a new option to read the position of a motor as the absolute angle from 0 to 2*pi radians. By default the motor position is measured as the total +/- rotation in either direction, relative to the starting position.

• nxt_ros_test
  Working.

• nxt_rviz_plugin
  Disabled, it is not compatible with the ROS Fuerte release of RViz which was ported to Qt.

nxt_robots stack:

• nxt_robot_gyro_car
  Working. The robot model can be viewed in Rviz.

• nxt_robot_kit_test
  Working. This is a test package, so the robot looks like a pile of disconnected LEGO parts when viewed in Rviz.

• nxt_robot_sensor_car
  Working. The robot model can be viewed in Rviz.

nxt_apps stack:

• nxt_assisted_teleop
  Compiles ok, un-tested.

• nxt_teleop
  Working.

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###Installation

Upgrade the firmware on your NXT brick.
The minimum required version is 1.28, but 1.31 is the latest as of Jan 2016.

Clone the Fuerte branch of this repository:

$ cd ~/
$ git clone https://github.com/dbworth/NXT-ROS.git --branch fuerte

Copy the 3 stacks into your ROS Workspace.
Note: you only need the nxt stack to get started.

$ cp NXT-ROS/nxt ~/ROS_WORKSPACE/
$ cp NXT-ROS/nxt_robots ~/ROS_WORKSPACE/
$ cp NXT-ROS/nxt_apps ~/ROS_WORKSPACE/

Add the stacks to your $ROS_PACKAGE_PATH.
You might like to add these commands to your ~/.bashrc file.

$ export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:/ros_workspace/nxt
$ export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:/ros_workspace/nxt_robots
$ export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:~/ros_workspace/nxt_apps

Install dependencies:

NXT-Python v2.2.2 is automatically installed in the /src directory of the nxt_python package when we run rosmake.

You can install the other dependencies using the Ubuntu Package Manager or ROSdep:

$ sudo apt-get install ros-fuerte-ros-comm ros-fuerte-common-msgs ros-fuerte-joystick-drivers ros-fuerte-visualization ros-fuerte-navigation ros-fuerte-orocos-kinematics-dynamics
$ sudo aptitude install libusb-dev python-usb python-bluez

or

$ sudo rosdep install -y nxt
$ sudo rosdep install -y nxt_robots
$ sudo rosdep install -y nxt_apps

Compile the stacks of packages:

$ rosmake nxt
$ rosmake nxt_robots
$ rosmake nxt_apps

Set the USB permissions:

Add a new group:

$ sudo groupadd lego

Add yourself to that group:

$ sudo usermod -a -G lego USERNAME

For Ubuntu versions before 12.0, 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

For 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

Restart udev:

$ sudo restart udev

Log-out or restart your computer.

###Test the installation:

Connect your NXT Brick to the computer via USB cable.
You can run this utility to display information about your Brick:

$ rosrun nxt_python nxt_test

You should see the following output:

NXT brick name: MyBrick
Host address: 00:16:00:00:D3:00
Bluetooth signal strength: 0
Free user flash: 25872
Protocol version 1.124
Firmware version 1.31
Battery level 7602 mV

nxt stack:

Connect a touch sensor to port 1.

$ roscore
$ rosrun nxt_python touch_sensor_test.py

When you push the touch sensor, the output on the screen will change.
The node automatically exits are 5 seconds.

Now connect a motor to port A.

$ roslaunch nxt_ros_test test.launch

Check the status of the touch sensor using ROS:

$ rostopic echo /my_touch_sensor

When you push the touch sensor, the boolean value published in the ROS msg will change.

Read the position of the motor using ROS:

$ rostopic echo /joint_states

When you rotate the motor shaft by hand, the position and velocity values published in the ROS msg will change.

Make the motor rotate using ROS:

$ rostopic pub /joint_command nxt_msgs/JointCommand '{name: 'motor_joint', effort: 0.8}' --once

The 'effort' value can be in the range 0.0 to 1.25, with +/- to specify the direction.

To stop the motor, set the effort to 0.0:

$ rostopic pub /joint_command nxt_msgs/JointCommand '{name: 'motor_joint', effort: 0.0}' --once

nxt_robots stack:

Connect motors to Port A and Port B of the NXT Brick.
Connect an ultrasonic sensor to Port 2.
Connect the NXT to your computer.

$ roscore

In a new terminal:

$ roslaunch nxt_robot_gyro_car robot.launch

In a new terminal:

$ rosrun rviz rviz

In Rviz you'll need to set the Fixed Frame to '/base_link'.
Add a RobotModel display so you can visualize the robot.

nxt_apps stack:

In a new terminal:

$ roslaunch nxt_teleop teleop_keyboard.launch

Use the arrow keys to control the motors.

You can also use a joystick.
Configure the joystick using the instructions here:
http://wiki.ros.org/joy/Tutorials/ConfiguringALinuxJoystick

$ roslaunch nxt_teleop teleop_joy.launch

With the Microsoft XBox 360 joystick, you need to hold down the top-left button. The left joystick controls turning, the right joystick goes forward.

MotorControl firmware:

MotorControl is a program that can be optionally installed on your NXT Brick to provide more accurate control of the motors using python. Instead of sending commands directly to the motor, you send commands to the onboard controller which tracks the status of the motors.

Copy the MotorControl program to your NXT Brick.
You must first change to the directory containing the *.rxe file:

$ roscd nxt_python/src/MotorControl/

Connect to your Brick via USB cable and transfer the program binary:

$ rosrun nxt_python nxt_push MotorControl22.rxe

Test the controller using the provided test script:

$ roscore
$ rosrun nxt_python motor_cont_test.py

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