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

# useCtrlNoise

> Apply Gaussian noise to controls for robustness testing

Adds Gaussian noise to actuator controls each frame. Useful for testing controller robustness or simulating actuator noise.

## Signature

```tsx theme={null}
useCtrlNoise(config: {
  rate?: number;
  std?: number;
  enabled?: boolean;
}): void
```

## Usage

```tsx theme={null}
import { useCtrlNoise } from "mujoco-react";

function NoisySimulation() {
  useCtrlNoise({
    rate: 0.01,
    std: 0.05,
    enabled: true,
  });

  return null;
}
```

## Config

| Field     | Type      | Default | Description                                             |
| --------- | --------- | ------- | ------------------------------------------------------- |
| `rate`    | `number`  | `0.01`  | Exponential filter rate (0 = no change, 1 = pure noise) |
| `std`     | `number`  | `0.05`  | Standard deviation of the Gaussian noise                |
| `enabled` | `boolean` | `true`  | Enable/disable noise injection                          |

## How It Works

Each frame, for each actuator:

```
noise[i] = (1 - rate) * noise[i] + rate * N(0, std)
ctrl[i] += noise[i]
```

This produces temporally-correlated noise (not white noise), which is more physically realistic. The `rate` parameter controls the correlation:

* **Low rate** (0.01): Smooth, slowly-varying noise
* **High rate** (0.5): Rapidly-changing noise
* **Rate = 1.0**: Independent samples each frame (white noise)

## Notes

* Noise is applied in `useBeforePhysicsStep`, composing with other control sources
* The noise state is maintained internally — each actuator has its own noise value
* Disable with `enabled: false` rather than removing the hook