About | Support | Discussion Forum | Index | Service Status | ros @ Robotics Stack Exchange

melodic noetic   Show EOL distros: 

Supported Hardware

This node should work with any joystick that is supported by Linux.

API Stability

The ROS API of this node should be considered stable.

Official Documentation

Nodes

joy_node

Provides a generic Linux joystick node.

Subscribed Topics

joy/set_feedback (sensor_msgs/JoyFeedbackArray)

• Force feedback control.

Published Topics

joy (sensor_msgs/Joy)

• Outputs the joystick state.

Parameters

~dev (str, default: "/dev/input/js0")

• Linux joystick device from which to read joystick events.

~deadzone (double, default: 0.05)

• Amount by which the joystick has to move before it is considered to be off-center. This parameter is specified relative to an axis normalized between -1 and 1. Thus, 0.1 means that the joystick has to move 10% of the way to the edge of an axis's range before that axis will output a non-zero value. Linux does its own deadzone processing, so in many cases this value can be set to zero.

~autorepeat_rate (double, default: 0.0 (disabled))

• Rate in Hz at which a joystick that has a non-changing state will resend the previously sent message.

~coalesce_interval (double, default: 0.001)

• Axis events that are received within coalesce_interval (seconds) of each other are sent out in a single ROS message. Since the kernel sends each axis motion as a separate event, coalescing greatly reduces the rate at which messages are sent. This option can also be used to limit the rate of outgoing messages. Button events are always sent out immediately to avoid missing button presses.

~default_trig_val (bool, default: false)

• When this parameter is false, each button and axis will report a value of 0 until it gets pressed/touched. This might be a problem e.g. for the trigger axes which should report 1.0 in their default untouched position. Setting this parameter to true forces the driver to read the actual joystick button values on startup and report the correct values even before the buttons/axes were touched. There is a small probability that reading out the initial state will not work for some combinations of gamepads and kernel versions, and that is why this parameter is false by default.

~dev_ff (str, default: "/dev/input/event0" (New in Noetic: autodetection is tried if this parameter is not specified))

• The device to use for accessing force feedback function. It is usually one of /dev/input/event* devices. You can use udevadm monitor command when plugging in the gamepad to tell the right event file name.

Using this Package

For an example of using joy_node to control a teleoperation node with a joystick, see the tutorials.

In some cases, multiple joysticks may control a single robot. For example, a user may use the default joystick to drive a robot, but a second user may wish to use a different kind. Since the button mappings on each joystick may be different, it will be necessary to remap buttons on one joystick so they can match. See the Joystick Remapper package for details.

Force feedback

Most gamepads offer a force feedback function that can vibrate the gamepad. For it to work correctly, you have to specify correctly the ~dev_ff parameter (on Noetic, when this parameter is empty, an autodetection algorithm tries to guess it).

Once the force feedback device is correctly set, you can control the force feedback using the joy/set_feedback topic. Before trying it out, make sure the jumping gamepad on your table will not destroy anything. An example usage can look like this:

rostopic pub -1 /joy/set_feedback sensor_msgs/JoyFeedbackArray "array: [ {type: 1, id: 0, intensity: 1.0} ]"

The intensity field specifies the strength of the vibrations. 0 is no vibration, 1 is maximum.

Finding the correct force feedback device

If you do not know the correct value of the ~dev_ff parameter, here are a few tips to figure it out.

One way is to look into folder /dev/input/by-id.

ls -la /dev/input/by-id/

The output can look like this:

lrwxrwxrwx 1 root root  10 Aug 12 19:08 usb-Chicony_Electronics_Co._Ltd._Integrated_Camera_0001-event-if00 -> ../event14
...
lrwxrwxrwx 1 root root  10 Aug 19 16:02 usb-Microsoft_Controller_3039373132373036323336303438-event-joystick -> ../event18
lrwxrwxrwx 1 root root   6 Aug 19 16:02 usb-Microsoft_Controller_3039373132373036323336303438-joystick -> ../js0

The listing shows a few symbolic links, one of them pointing to your js0 device. The symlink will end with -joystick. Look for a similarly named file, just ending with -event-joystick. You can either directly pass this value to ~dev_ff (in this case /dev/input/by-id/usb-Microsoft_Controller_3039373132373036323336303438-event-joystick), or you can follow the symbolic link to one of the /dev/input/event* files and set the event file as the parameter value (which would be /dev/input/event18 in this example).

Some gamepads will not appear in the /dev/input/by-id listing - e.g. Xbox ONE gamepad connected via the wireless dongle and xow driver.

In this case, the easiest way to find the force feedback event device is to disconnect the gamepad (or dongle) and run

udevadm monitor

Here is an example output of this command after plugging the gamepad back:

KERNEL[181478.230525] add      /devices/pci0000:00/0000:00:08.1/0000:06:00.4/usb6/6-2 (usb)
...
KERNEL[181481.500440] add      /devices/virtual/input/input24 (input)
KERNEL[181481.500573] add      /devices/virtual/input/input24/event18 (input)
KERNEL[181481.500659] add      /devices/virtual/input/input24/js0 (input)
UDEV  [181481.502263] add      /devices/virtual/input/input24 (input)
UDEV  [181481.512791] add      /devices/virtual/input/input24/js0 (input)
UDEV  [181481.551194] add      /devices/virtual/input/input24/event18 (input)

You can see that I have connected a gamepad that appeared as /dev/input/js0 with the force feedback device being /dev/input/event18.

Application

Microsoft Xbox 360 Wireless Controller for Windows

Table of index number of /joy.buttons:

Microsoft Xbox 360 Wireless Controller for Linux

Table of index number of /joy.buttons:

Table of index number of /joy.axes:

Microsoft Xbox 360 Wired Controller for Linux

Table of index number of /joy.buttons:

Table of index number of /joy.axes:

Logitech Wireless Gamepad F710 (DirectInput Mode)

Table of index number of /joy.buttons:

Table of index number of /joy.axes: