> ## Documentation Index
> Fetch the complete documentation index at: https://docs.wuji.tech/llms.txt
> Use this file to discover all available pages before exploring further.

# Maintenance

<Info>
  This page covers device-side behavior and upkeep: fault severity and stop behavior, emergency stop and fault-clearing recovery, hazard zones and responsibility boundaries in joint operation, plus the user-serviceable boundary, routine checks, and storage and transport requirements. To diagnose by symptom, see [Troubleshooting](/en/docs/wuji-hand/latest/troubleshooting).
</Info>

## Safe Stop and Fault Recovery

Fault severity sets how the device stops, and communication loss, emergency stop, the fault-clearing reset, hazard zones, and the responsibility split for running with a robot arm each follow a fixed convention.

### Fault Severity and Stop Behavior

Decode a device error code with `WujiHand2.describe_error(code)`. The result carries a severity level (`severity`) and a clear policy (`clear_policy`). Each severity maps to a stop behavior:

| Severity | Stop behavior | Typical trigger |
| - | - | - |
| `Warning` | No stop, operation continues | Early warnings such as temperature nearing the limit, a rising encoder error rate, or a stalled joint |
| `DeferredStop` | Stops after the current motion finishes | Issues that call for an orderly stop, such as a communication timeout or over-temperature |
| `ImmediateStop` | Stops immediately | Under-voltage or over-voltage, over-current, driver faults, encoder failures |
| `Fatal` | Stops and can't be cleared | Repeated over-current, hardware damage, power-on self-check failure |

Clear policies come in three kinds: `AutoClear` (clears itself once the cause is removed), `ManualClear` (needs a clear-fault call), and `NonClearable` (needs a power cycle, and if it recurs, stop using the device).

### Communication Loss Behavior

If communication with the host drops while the hand is enabled, the device stops the motors and reports a fault. It doesn't resume motion on its own once communication returns—call `enable()` again (firmware v2.1.0 and later).

### Emergency Stop

* **Software emergency stop**: `hand.emergency_stop()` stops the whole hand immediately and takes no mask
* **Hardware emergency stop interface**: not available in this version

<Warning>
  When running with a robot arm, consider wiring the hand's power supply into the arm's emergency-stop circuit. A specific wiring approach isn't available yet and will be added later.
</Warning>

### Torque State After a Fault

A `Warning` doesn't stop the device, so it keeps running. After a `DeferredStop`, `ImmediateStop`, or `Fatal` fault stops the device, the joints go limp. For the meaning of each level, see [Fault Severity and Stop Behavior](#fault-severity-and-stop-behavior) above. Assess the risk of dropping a held object in your application.

### Clear Faults and Reset Safely

1. Subscribe to `joint_diagnostics` to read the active error codes, then call `info = describe_error(code)`.
2. If `code` is `0`, no fault is active. Keep monitoring the device.
3. If `info` is `None`, retain the original error code and contact support to confirm how to handle it. Don't continue with the fault-clearing steps below.
4. Otherwise, read `cause` and `resolution` from `info`, then address the reported cause.
5. Clear the fault: for `AutoClear`, wait for it to clear itself. For `ManualClear`, call `clear_fault()` (optionally with a 20-bit mask to target specific joints).
6. Enable again with `enable()`, and confirm the status light turns white solid.
7. For `NonClearable` (Fatal) faults, power-cycle the device. If the fault recurs, stop using the device and contact support.

### Hazard Zones

* **Pinch points**: the gaps between fingers and at the joints. Always run the hand with the soft pad and skin fitted, and keep clear while the hand moves
* **Hot zone**: the motor area in the palm. Don't touch it directly after a high load
* **Cable zone**: the flex cables on the finger surface and the cables leaving the wrist. Avoid scratching and pulling

### Safety Responsibilities When Running With a Robot Arm

* The hand has no awareness of the arm's motion planning. Arm-side collision detection, speed limits, and workspace isolation are the integrator's responsibility
* The hand side provides its own over-torque, over-temperature, and communication-loss protection, and records impact detection events

<Info>
  A complete breakdown of responsibilities isn't available yet and will be added later.
</Info>

## Maintenance and Consumables

The skin, soft pad, and whole fingers are user-replaceable, while board-level parts are not. Daily checks, storage, transport, and warranty each carry their own requirements.

### What You Can Service

| Part | What you can do | Notes |
| - | - | - |
| Skin | Remove and replace it yourself | Always run the hand with the skin fitted, never without it |
| Nails | Replaceable | — |
| Soft pad | Replaceable | See [Hardware Integration](/en/docs/wuji-hand/latest/hardware-integration#remove-and-refit-the-soft-pad) for removal and refitting steps |
| A whole finger | Removable and replaceable with the device powered down | Each finger has its own mechanical and communication interface, so you can swap a whole finger. Replacement steps aren't available yet |
| Palm main board / driver board | Don't disassemble | Disassembly affects the warranty, and the warranty terms aren't available yet |

<Warning>
  Power the device down before removing or refitting the skin and soft pad. The flex cables on the finger surface are fragile, so avoid scratching and squeezing them during the work (see [User Notice](/en/docs/wuji-hand/latest/user-notice#cable-and-flex-cable-protection)).
</Warning>

### Daily Checks and Maintenance Intervals

Check before each day's use:

* No visible damage, with the skin properly fitted
* No cable damage and no loose connectors
* The power-on self-check passes (the status light reaches white breathing)

### Storage and Transport

* **Storage**: power down and store in a dry environment, with the fingers extended flat in the box
* **Transport**: use the original packaging, which is designed for high-temperature, high-humidity, drop, stacking, and vibration conditions

### Warranty and Support

The warranty scope and repair process aren't available yet and will be added later. If a prototype is damaged, contact your point of contact or [support@wuji.tech](mailto:support@wuji.tech) immediately.


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