Using an Xbox Controller on Ubuntu and ROS

Curiosity struck again and so I decided to try and use an wired Xbox controller I had laying around as an alternate input method (typing in numbers wasn’t doing it for me anymore).

xboxdrv

Thankfully most of the hard-work has already been done for me. Although Ubuntu (LTS 12.04 on my testing desktop and 13.04 ARM on the Beaglebone Black) already has default drivers for joysticks/gamepads and the Xbox controller specifically, general internet consensus is that a third-party user-space driver called xboxdrv is a much better alternative.

Disabling and blacklisting the kernel driver

The blacklisting technique is from Jonas Wagner.

Before using xboxdrv, the default driver must be unloaded or blacklisted or both. In case the default xpad driver is already loaded

sudo rmmod xpad

will unload the driver. A more permanent solution is to blacklist the module so it never is automatically loaded

sudo su
echo "blacklist xpad" > /etc/modprobe.d/blacklist.conf

Installing xboxdrv

Rather than install the package from the default Ubuntu repositories, using the developer’s repository ensures the latest version is installed.

sudo add-apt-repository ppa:grumbel/ppa
sudo apt-get update
sudo apt-get install xboxdrv

Using xboxdrv

Starting the driver is really simple since it does the configuration and searching for you.

xboxdrv # might need root access

Using the --silent option might be preferred once its clear that the driver is working with your install.

If you didn’t use the silent option, there should be all sorts of information being spit out onto the console window detailing all the button presses and trigger/joystick movements.

Checking ls -l /dev/input should reveal a new entry named js0 or something similar (maybe a different number). There is where controller is now mounted.

Quirks and troubles I ran into

I had some pretty frustrating experiences trying to setup xboxdrv. I’m still not quite sure why but my Xbox 360 wired controller only worked when it was plugged into a certain USB port on my computer. I had an error saying that xboxdrv was unable to claim the device. Trying a different USB port solved the problem.

Joy of ROS

And with ROS, once again the hard-work has already been done for me. The ROS package joy translates Xbox (old/360) (wired/wireless) inputs into ROS messages in the joy topic. I had trouble following the tutorial on setting up the turtlesim demo since it was written for groovy and also a general lack of familiarity with C++.

Using the ROS tutorials on writing publishers and subscribers, I wrote a node that converted Xbox controller inputs from joy into commands for the turtlesim node.

    #!/usr/bin/env python
    import rospy
    from geometry_msgs.msg import Twist
    from sensor_msgs.msg import Joy

    # Author: Andrew Dai
    # This ROS Node converts Joystick inputs from the joy node
    # into commands for turtlesim

    # Receives joystick messages (subscribed to Joy topic)
    # then converts the joysick inputs into Twist commands
    # axis 1 aka left stick vertical controls linear speed
    # axis 0 aka left stick horizonal controls angular speed
    def callback(data):
        twist = Twist()
        twist.linear.x = 4*data.axes[1]
        twist.angular.z = 4*data.axes[0]
        pub.publish(twist)

    # Intializes everything
    def start():
        # publishing to "turtle1/cmd_vel" to control turtle1
        global pub
        pub = rospy.Publisher('turtle1/cmd_vel', Twist)
        # subscribed to joystick inputs on topic "joy"
        rospy.Subscriber("joy", Joy, callback)
        # starts the node
        rospy.init_node('Joy2Turtle')
        rospy.spin()

    if __name__ == '__main__':
        start()
    

Also on my Github

Actually running the test

1. Install ROS and setup the catkin workspace

2. Making a new project with the right dependencies (rospy, std_msgs, joy) or just cloning my repository into the src folder of the workspace

3. Installing xboxdrv

4. Make sure the node is executable. chmod +x src/joystick-tests/turtle\_teleop\_joy.py

5. Start everything!

    # starting ROS
    roscore
   
    # xboxdrv in silent mode (in a new console window)
    sudo xboxdrv --silent
   
    # starting the joy node (in another new window)
    rosrun joy joy_node
   
    # starting turtlesim (in another new window)
    rosrun turtlesim turtlesim_node
   
    # starting the "translator" node (in another new window)
    rosrun beaglecar turtle_teleop_joy.py
   

I tested this by writing a teleop test for my beaglecar. Spoiler: it works!