# Motor Test Joystick (Issue #513)

Terminal-based interactive joystick for bench testing SaltyBot motors via Termux.

## Quick Start

```bash
python3 motor_test_joystick.py  # ROS2 mode
python3 motor_test_joystick.py --backend websocket --host <jetson-ip>  # WebSocket mode
```

## Controls

| Key | Action |
|-----|--------|
| **W** / **↑** | Forward (linear +X) |
| **S** / **↓** | Reverse (linear -X) |
| **A** / **←** | Turn left (angular +Z) |
| **D** / **→** | Turn right (angular -Z) |
| **SPACE** | E-stop toggle |
| **R** | Reset velocities |
| **Q** | Quit |

## Features

- Real-time velocity feedback with bar graphs
- Spacebar e-stop (instantly zeros velocity)
- 500ms timeout safety (sends zero if idle)
- Conservative defaults: 0.1 m/s linear, 0.3 rad/s angular
- Dual backend: ROS2 (/cmd_vel) or WebSocket
- Graceful fallback if ROS2 unavailable

## Usage Examples

```bash
# Standard ROS2 mode
python3 motor_test_joystick.py

# WebSocket mode (fallback)
python3 motor_test_joystick.py --backend websocket --host 192.168.1.100

# Custom velocity limits
python3 motor_test_joystick.py --linear-max 0.5 --angular-max 1.0
```

## Architecture

- **MotorTestController**: State machine, velocity limiting, timeout enforcement
- **MotorTestNode** (ROS2): Twist publisher to /cmd_vel
- **WebSocketController** (fallback): JSON messages to Jetson
- **Curses UI**: Non-blocking input, real-time feedback, status display

## Safety

- Conservative defaults (0.1/0.3 m/s)
- E-stop button (spacebar)
- 500ms timeout (auto-zero velocity)
- Input clamping & exponential decay

## Related Issues

- #420 — Termux bootstrap & Android phone node
- #512 — Autonomous arming (uses /cmd_vel)