# key_teleop

*This file is ai generated. Do not edit this file directly. Instead, edit the node source code and run the generate-node-docs command to update this file.*

## Description

The `key_teleop` node provides a terminal-based keyboard teleoperation interface for controlling robot velocity using arrow keys. It uses curses to create a text-based interface in the terminal, allowing users to control linear and angular velocities with simple key presses.

## Publishers

| Topic | Type | Description |
|-------|------|-------------|
| `key_vel` | `geometry_msgs/msg/TwistStamped` or `geometry_msgs/msg/Twist` | Publishes velocity commands based on arrow key inputs. Type depends on `twist_stamped_enabled` parameter |

## Parameters

| Parameter | Type | Default | Description |
|-----------|------|---------|-------------|
| `twist_stamped_enabled` | bool | true | If true, publishes `TwistStamped` messages; if false, publishes `Twist` messages |
| `hz` | int | 10 | Publishing rate in Hz |
| `forward_rate` | double | 0.8 | Linear velocity scale factor for forward movement (m/s) |
| `backward_rate` | double | 0.5 | Linear velocity scale factor for backward movement (m/s) |
| `rotation_rate` | double | 1.0 | Angular velocity scale factor for rotation (rad/s) |

## Example Usage

### Basic Launch

```bash
ros2 run key_teleop key_teleop
```

### Launch with Parameters

```bash
ros2 run key_teleop key_teleop --ros-args \
  -p hz:=20 \
  -p forward_rate:=1.0 \
  -p backward_rate:=0.5 \
  -p rotation_rate:=2.0 \
  -p twist_stamped_enabled:=false
```

### Launch with Configuration File

```bash
ros2 run key_teleop key_teleop --ros-args --params-file /path/to/config.yaml
```

### Example Configuration File

```yaml
key_teleop:
  ros__parameters:
    hz: 10
    forward_rate: 0.8
    backward_rate: 0.5
    rotation_rate: 1.0
    twist_stamped_enabled: true
```

### Example Launch File

```python
from launch import LaunchDescription
from launch_ros.actions import Node
from ament_index_python.packages import get_package_share_directory
import os

def generate_launch_description():
    config_file = os.path.join(
        get_package_share_directory('key_teleop'),
        'config', 'key_teleop.yaml'
    )
    
    return LaunchDescription([
        Node(
            package='key_teleop',
            executable='key_teleop',
            parameters=[config_file],
            output='screen',
            emulate_tty=True  # Important for curses to work properly
        )
    ])
```

### Remap Output Topic

```bash
ros2 run key_teleop key_teleop --ros-args -r key_vel:=cmd_vel
```

## Operation

### Keyboard Controls

| Key | Action |
|-----|--------|
| **↑** (Up Arrow) | Move forward |
| **↓** (Down Arrow) | Move backward |
| **←** (Left Arrow) | Rotate left (counterclockwise) |
| **→** (Right Arrow) | Rotate right (clockwise) |
| **q** | Quit the node |

### Behavior

- Multiple arrow keys can be pressed simultaneously for combined motion
- Key presses are effective for 0.5 seconds; hold the key to maintain velocity
- Linear velocity is multiplied by `forward_rate` when moving forward, `backward_rate` when moving backward
- Angular velocity is multiplied by `rotation_rate`
- The terminal displays current linear and angular velocities in real-time

## Notes

- The node requires a terminal that supports curses (most Linux/Unix terminals)
- The node uses a text-based interface, so it runs directly in the terminal without a separate window
- Velocity commands are published at the rate specified by the `hz` parameter
- Keys have a 0.5-second timeout; if not pressed again within that time, the velocity component becomes zero
- The frame_id in published TwistStamped messages is set to "key_teleop"
- Linear velocities are in m/s, angular velocities are in rad/s
- For proper operation in launch files, use `emulate_tty=True` and `output='screen'`