sawJoystick

This SAW component contains code for interfacing with the Linux joystick API. It compiles on Linux and hasn't been tested on other OSs.

The ros folder contains code for a ROS node that interfaces with the sawJoystick component and publishes the analog and digital inputs. To build the ROS node, make sure you use catkin build for ROS 1 or colcon for ROS 2.

If needed, one can also add OpenIGTLink support using sawOpenIGTLink (contact the sawJoystick developers if you need help with this).

Links

• License: http://github.com/jhu-cisst/cisst/blob/master/license.txt
• JHU-LCSR software: http://jhu-lcsr.github.io/software/

Dependencies

• cisst libraries: https://github.com/jhu-cisst/cisst
• Qt for user interface
• ROS (optional)
• A Linux Joystick compatible device

Devices supported

Your device needs to be supported as a joystick under Linux. You can test your device using jstest-gtk (on Ubuntu, install with sudo apt install jstest-gtk).

Some cheap foot pedals can be configured to show up as joysticks on Linux. This usually requires to configure the foot pedals using a small utility program that unfortunately runs on Windows. Look for wording like "multimedia function, game controller functions." (from Amazon listing).

Build

You can find some documentation re. compiling cisst and SAW components for in the dVRK wiki:

• ROS 1
• ROS 2

For Linux with ROS, we provide a VCS files to retrieve all the git repositories you need for sawJoystick in the vcs directory.

Running the examples

Linux device

When connecting your joystick to your computer, a pseudo device will be added to the /dev/input directory.   Usually something like /dev/input/js0, /dev/input/js1... Using the command dmesg can help identify which device is used. Check the file permissions on said device, e.g.,

ls -al /dev/input/js0
crw-rw-r--+ 1 root input 13, 0 Jan  6 13:39 /dev/input/js0

On Ubuntu, the OS usually grants permission to all users to read. To grant permissions to read and write to the device, use the command sudo adduser <user_id> input to add users to the input group. Please note that the user has to logout/login for the new group membership to take effect.

Main example

The main example provided is sawJoystickQtExample. The command line options are:

sawJoystickQtExample:
 -j <value>, --json-config <value> : json configuration file (optional)
 -d <value>, --device <value> : device (e.g. /dev/input/js0...) (optional)
 -D, --dark-mode : replaces the default Qt palette with darker colors (optional)
 -m, --component-manager : JSON file to configure component manager (optional)

Configuration file

The configuration file can be used to specify the device to use (vs specifying it on the command line). It can also be used to convert some of the signals to different outputs. For example, one can create a new interface with a "button" event using one of the buttons from the joystick. See examples in core/share.

ROS

Please read the section above for the configuration file description. The ROS node is joystick and can be found in the package joystick:

roscd saw_joystick_config
rosrun joystick joystick -d /dev/input/js0

The ROS node has a few more command line options:

/home/anton/catkin_ws/devel/lib/joystick/joystick:
 -j <value>, --json-config <value> : json configuration file (optional)
 -d <value>, --device <value> : device (e.g. /dev/input/js0...) (optional)
 -p <value>, --ros-period <value> : period in seconds to read all components and publish (default 0.02, 20 ms, 50Hz).  There is no point to have a period higher than the tracker's period (optional)
 -P <value>, --tf-ros-period <value> : period in seconds to read all components and broadcast tf2 (default 0.02, 20 ms, 50Hz).  There is no point to have a period higher than the tracker's period (optional)
 -D, --dark-mode : replaces the default Qt palette with darker colors (optional)
 -m, --component-manager : JSON file to configure component manager (optional)

Once the node is started AND connected, the following ROS topic should appear:

/joystick/input_data