Eve Joystick

ROS2 node that interfaces with physical joystick hardware and converts joystick input into Ackermann drive commands for vehicle control. Provides safety gating through enable and deadman switches.

Features

• Hardware integration: Uses the ROS joy package to read joystick input from USB devices
• Ackermann command conversion: Maps joystick axes to steering angle and speed commands
• OSCC Arming Control: Interface to arm/disarm the OSCC board via a service call with vibration feedback
• Output topic toggling: Allows switching between standard Ackermann commands and ROSCCO commands via a joystick button
• Safety gating: Requires the enable button to be held for commands to be published
• Idle state tracking: Publishes idle status for use by the ackermann mux
• Configurable mapping: Supports custom axis assignments, max speeds, steering limits, and axis inversion

Configuration

The node is configured via a YAML file (see config/joy_config.yaml). Key parameters:

Joystick Node (hardware driver)

• deadzone: Joystick deadzone threshold to filter small movements (default: 0.05)

Joystick Interfacing Node

• enable_axis: Joystick axis index for the enable button (must be pressed ≤ -0.9)
• toggle_button: Joystick button index to toggle between Ackermann and ROSCCO output (default: 0)
• arming_button: Joystick button index to arm/disarm the vehicle (default: 0)
• steering_axis: Joystick axis index for steering control (left/right)
• throttle_axis: Joystick axis index for throttle control (forward/backward)
• ackermann_max_speed: Maximum speed in m/s for Ackermann mode (default: 2.0)
• ackermann_max_steering_angle: Maximum steering angle in radians for Ackermann mode (default: 0.5)
• roscco_max_speed: Maximum speed in m/s for ROSCCO mode (default: 1.0)
• roscco_max_steering_angle: Maximum steering angle in radians for ROSCCO mode (default: 0.3)
• invert_steering: Invert steering direction (default: false)
• invert_throttle: Invert throttle direction (default: false)
• toggle_vibration_intensity: Rumble intensity during toggles (default: 0.5)
• toggle_vibration_duration_ms: Duration of rumble pulses in ms (default: 100)

Usage

Launch the node with the default configuration:

ros2 launch joystick_interfacing joystick_interfacing.launch.yaml

The node will automatically detect and read from /dev/input/js0 (or the device specified in the joy_node configuration).

Topics and Services

Subscribed

• /joy (sensor_msgs/msg/Joy): Raw joystick input from the hardware driver
• /oscc_interfacing/is_armed (std_msgs/msg/Bool): Current arming state of the vehicle

Published

• /joystick/ackermann (ackermann_msgs/msg/AckermannDriveStamped): Ackermann drive commands
• /roscco (roscco_msg/msg/Roscco): ROSCCO drive commands (used when toggled)
• /joystick/is_idle (std_msgs/msg/Bool): Idle state indicator (true when joystick is not active)
• /joystick/state (std_msgs/msg/Int8): Current operation mode (0: NULL, 1: ACKERMANN, 2: ROSCCO)
• /joy/set_feedback (sensor_msgs/msg/JoyFeedback): Force feedback (vibration) commands to the joystick

Service Clients

• /oscc_interfacing/arm (std_srvs/srv/SetBool): Service to arm (true) or disarm (false) the vehicle

How It Works

1. Hardware Input: The joy_node reads raw joystick data from the USB device and publishes to /joy.

2. Arming Control: When the arming_button is pressed (rising edge), the node calls the /oscc_interfacing/arm service to toggle the vehicle state.
   • Arming: Triggers a double vibration pulse.
   • Disarming: Triggers a single long (500ms) vibration pulse.

3. Safety Check: The interfacing node requires the enable axis to be pressed (value ≤ -0.9). If not pressed, a zero-velocity command is published and the idle state is set to true.

4. Command Conversion: When safety conditions are met:
   • Steering and throttle are scaled based on the current mode (Ackermann or ROSCCO) using their respective max_speed and max_steering_angle parameters.
   • Inversion flags are applied if configured.
5. Topic Selection: If the toggle_button is pressed (rising edge), the node switches between publishing to /joystick/ackermann and /roscco.
   • Switch to ROSCCO: Double vibration pulse.
   • Switch to Ackermann: Single vibration pulse.
6. Output: The converted command is published with the current timestamp, and the idle state is set to false.

Feedback Patterns

The node provides haptic feedback via joystick vibration:

• Toggle to ROSCCO: 2 pulses (default duration)
• Toggle to Ackermann: 1 pulse (default duration)
• Armed Successfully: 2 pulses (default duration)
• Disarmed Successfully: 1 long pulse (500ms)

Finding Joystick Axis Indices

To determine which axis indices correspond to your joystick buttons and sticks, run the joy_node and echo the /joy topic. Then press buttons and move sticks while observing the axes and buttons arrays in the output. Note that triggers are typically reported as axes, not buttons.