# Actuator plugins
## PID
The `mujoco.pid` actuator plugin implements a configurable [PID controller](https://en.wikipedia.org/wiki/Proportional%E2%80%93integral%E2%80%93derivative_controller):
$$f(t) = K_\text{p} e(t) + K_\text{i} \int_0^t e(\tau) \mathrm{d}\tau + K_\text{d} \frac{\mathrm{d}e(t)}{\mathrm{d}t},$$
where $e(t) = u(t) - \ell(t)$ is the difference between the control $u$ and the actuator length $\ell$.
You can use it like:
```xml
```
The available options are:
|Attribute | Default | Meaning |
|----------|---------|---------|
|`kp` | 0 | **P** gain for the controller. |
|`ki` | 0 | **I** gain for the controller.If nonzero, one activation variable will be added to `mjData.act`, containing the current I term (in units of force). |
|`kd` | 0 | **D** gain for the controller. |
|`imax` | Optional | If specified, the force produced by the I term will be clipped to the range `[-imax, imax]`. |
|`slewmax` | Optional | The maximum rate at which the setpoint for the PID controller can change.If a bigger change is requested between two timesteps, it will be clipped to the range `[ctrl - slewmax * dt, ctrl + slewmax * dt]`If specified, one activation variable will be added to `mjData.act` containing the previous value of `ctrl`. |