2-DOF PID controller, returned as a `pid2`

object or
`pidstd2`

object. `C2`

is in
parallel form if `C1`

is in parallel form, and standard
form if `C1`

is in standard form.

For example, suppose `C1`

is a continuous-time,
parallel-form `pid`

controller of the form:

Then `C2`

is a parallel-form 2-DOF
`pid2`

controller, which has two inputs and one
output. The relationship between the inputs, *r* and
*y*, and the output *u* of
`C2`

is given by:

The PID gains *K*_{p},
*K*_{i}, and
*K*_{d}, and the filter time
constant *T*_{f} are unchanged. The
setpoint weights *b* and *c* are specified
by the input arguments `b`

and `c`

, or
1 by default. For more information about 2-DOF PID controllers, see Two-Degree-of-Freedom PID Controllers.

The conversion also preserves the values of the properties
`Ts`

, `TimeUnit`

, ```
Sampling
Grid
```

, `IFormula`

, and
`DFormula`

.