# SUB Control

A deliberately small, low-bandwidth MAVLink controller for bench-testing an
ArduSub vehicle over a USB serial connection. It sends no parameter-list
request and no telemetry-stream request.

![SUB Control interface](docs/sub-control-interface.png)

The desktop window uses a local HTML/CSS/JavaScript interface rendered by the
Windows WebView. Python remains the only launcher and owns the MAVLink worker,
arming, logging, output limiting, and parameter writes. It does not run a web
server, open a browser tab, or require an internet connection.

The WebView is frameless and uses the compact title bar drawn by the interface.
The vehicle rail includes a local STL viewer: choose **Load STL** to start with
an orthographic top-view silhouette, then drag to orbit or use the mouse wheel
to zoom. A cached STL copy is stored locally under the ignored `runtime/`
directory so the model can be restored on the next launch.
STEP/STP CAD solids must first be tessellated/exported as STL because the
embedded renderer intentionally does not include a full CAD kernel.
Binary and ASCII STL faces are preserved in full; large assemblies are not
rendered by skipping triangles. Imports are limited to 30 MB to keep startup
and interactive orbiting responsive.

## Safety first

- Remove propellers for initial tests and restrain the vehicle.
- Verify the ArduSub frame and `SERVOx_FUNCTION`, motor direction, ESC range,
  leak/failsafe, and emergency-stop arrangements before arming.
- The application starts disarmed and limits pilot demand to 20% by default.
  Once armed, control movement is sent directly with no additional gate.
- Closing or disconnecting sends neutral controls and a disarm request, but a
  physical power cutoff is still required.

The controls are pilot-demand axes, not direct PWM values. ArduSub performs
the frame mixing and generates the configured ESC outputs. For ArduSub,
`MANUAL_CONTROL.z = 500` is neutral vertical thrust.

## Run on Windows

1. Install Python 3.11 or newer. A virtual environment installs packages, but
   it does not install Python itself.
2. Open PowerShell in this folder and run `./run.ps1` (or right-click it and
   choose **Run with PowerShell**).
3. Select the autopilot's COM port, then click **Connect**. Baud and control-rate
   settings are under the small `•••` link button (normally 57600 baud / 20 Hz).
4. Confirm `ArduSub` and a live heartbeat are shown.
5. Click **Set MANUAL**, then **ARM** only when the bench is safe.
6. Move the controls. Once armed, no additional enable button is needed.

`run.ps1` automatically creates a private `.venv` on the first run, installs
the versions declared in `requirements.txt`, and starts SUB Control. Later runs
reuse the same environment and update missing dependencies when necessary.
The `.venv` directory is intentionally ignored by Git: virtual environments
contain machine-specific executables and can be recreated from
`requirements.txt`.

## Repository layout

The Gitea repository is named `argo`. `SUB Control` is a normal directory inside
that repository containing this application. A Gitea **Project** is a planning
board for issues and tasks; source code is not attached to a Project board.
Git tracks the folder automatically because its files are committed on the
repository's `main` branch.

Keyboard controls for SimpleROV-3: W/S forward/back, A/D yaw left/right,
Q/E alternative yaw control, and R/F rise/dive.
Releasing movement keys eases their controls back to neutral.

## Three-thruster limitation

The common ArduSub `SimpleROV-3` arrangement controls forward, yaw, and depth.
It cannot independently control lateral, roll, or pitch. Accordingly, the main
pad is mapped to forward/yaw, while the vertical slider controls depth thrust.

## Link behavior

- MAVLink GCS heartbeat: 1 Hz
- `MANUAL_CONTROL`: selectable 10 or 20 Hz (default 20 Hz). Lower rates are
  intentionally excluded because they make short return ramps become abrupt
  steps at the flight controller.
- No full parameter download
- On connection, inherited bulk telemetry streams are stopped. Only
  `SYS_STATUS` at 1 Hz and `SERVO_OUTPUT_RAW` / `RC_CHANNELS` at 2 Hz are
  requested, in addition to the normal heartbeat and event-driven status text.
- Arm/disarm uses `MAV_CMD_COMPONENT_ARM_DISARM` and displays `COMMAND_ACK`
- Link health is based on received autopilot heartbeats
- Battery voltage is read from `SYS_STATUS` at 1 Hz and shown as pack voltage,
  estimated per-cell voltage, and a voltage-only percentage. Cell count,
  capacity, C rating, full/empty cell voltages, and warning percentage are
  configurable and saved locally in `battery_settings.json`. Capacity consumed
  cannot be measured without a current sensor.
- Servo configuration scans `SERVO1_FUNCTION` through `SERVO16_FUNCTION` and
  ArduSub's `MOT_1_DIRECTION` through `MOT_12_DIRECTION` one at a time, waiting
  for each response and retrying missed replies. A selected output can be
  assigned to Motor 1–12 or set unassigned. Motor direction is toggled with the
  corresponding `MOT_n_DIRECTION` value while disarmed; `SERVOx_REVERSED` is
  intentionally not used for Motor functions. It never downloads the full
  parameter list.
  The diagnostic scan also reads `SERVO1`–`SERVO3` MIN/TRIM/MAX and ArduSub's
  joystick gain values into the local session log; these values remain
  read-only in the application.
- Every session creates a local text log under `logs/`, including operator
  actions, outgoing manual-control values and commands, acknowledgements,
  status text, and all received MAVLink messages. This does not use ArduPilot's
  onboard logger or add any link traffic.

The car-style virtual joystick maps only to forward/reverse and continuous
differential turning; it never sends lateral motion. The joystick and vertical
slider ease back to center over 400 ms after mouse/key release, so neither can
be left commanding motion.
Heartbeat loss, disconnect, and disarm remain immediate safety stops and are
intentionally not eased.

In addition, transmitted pilot demands have a small 4% input deadband and a
0.8-second full-range slew limit. This makes both acceleration and deceleration
arrive at the flight controller as a sequence of stable intermediate values.
Forward and yaw are normalized as a SimpleROV-3 motor pair before the output
limit is applied, preventing their mixer contributions from adding beyond the
selected horizontal limit.

ArduPilot may ignore manual input when `MAV_GCS_SYSID` does not match this
application's system ID (default 255), or when `MAV_OPTIONS` does not allow
MAVLink input. Those parameters must already be correctly configured.