Joy Package

📦 Joy package for joystick_drivers repo

The joy package contains joy_node, a node that interfaces a generic joystick to ROS 2. This node publishes a “Joy” message, which contains the current state of each one of the joystick’s buttons and axes.

Published Topics

joy (sensor_msgs/msg/Joy): outputs the joystick state.

std_msgs/Header Message

More Info

A /joy message in ROS contains the state of the joystick’s axes and buttons and is typically published as a message of type sensor_msgs/Joy. Example:

header:
  seq: 123                      # Sequence number of the message
  stamp:
    secs: 1626442826            # Time of message publication
    nsecs: 123456789
  frame_id: ''                  # Frame ID (often empty for /joy messages)
 
axes: [0.0, 1.0, -0.5, 0.0]     # Array of axis positions (floats between -1.0 and 1.0)
buttons: [0, 0, 1, 0, 0, 1]     # Array of button states (0 or 1 for each button)

Explanation of Fields

• header: Contains metadata, such as sequence number, timestamp, and frame ID.
• axes: An array representing the position of each joystick axis. Each entry is a float, usually between -1.0 and 1.0, where:
  • Positive values indicate movement in one direction (e.g., right or up).
  • Negative values indicate movement in the opposite direction (e.g., left or down).
• buttons: An array where each entry is an integer (0 or 1) indicating the state of each button:
  • 0 means the button is not pressed.
  • 1 means the button is pressed.

Example with an Xbox Controller Layout

For an Xbox-style controller:

• axes might map as:
  • axes[0]: Left thumbstick horizontal (left-right)
  • axes[1]: Left thumbstick vertical (up-down)
  • axes[2]: Right thumbstick horizontal
  • axes[3]: Right thumbstick vertical
  • axes[4] and axes[5]: Triggers (often -1 to 1, depending on the driver)
• buttons might map as:
  • buttons[0]: A button
  • buttons[1]: B button
  • buttons[2]: X button
  • buttons[3]: Y button
  • Additional entries for shoulder buttons, triggers, and other controller buttons.