d2cOptions

Create option set for discrete- to continuous-time conversions

Syntax

```opts = d2cOptions opts = d2cOptions(Name,Value) ```

Description

`opts = d2cOptions` returns the default options for `d2c`.

`opts = d2cOptions(Name,Value)` creates an option set with the options specified by one or more `Name,Value` pair arguments.

Input Arguments

Name-Value Arguments

`method`

Discretization method, specified as one of the following values:

 `'zoh'` Zero-order hold, where `d2c` assumes that the control inputs are piecewise constant over the sample time `Ts`. `'foh'` Linear interpolation of the inputs (modified first-order hold). Assumes that the control inputs are piecewise linear over the sampling period. `'tustin'` Bilinear (Tustin) approximation. By default, `d2c` converts with no prewarp. To include prewarp, use the `PrewarpFrequency` option. `'matched'` Zero-pole matching method. (See [1], p. 224.)

For information about the algorithms for each `d2c` conversion method, see Continuous-Discrete Conversion Methods.

Default: `'zoh'`

`PrewarpFrequency`

Prewarp frequency for `'tustin'` method, specified in `rad/TimeUnit`, where `TimeUnit` is the time units, specified in the `TimeUnit` property, of the discrete-time system. Specify the prewarp frequency as a positive scalar value. A value of 0 corresponds to the `'tustin'` method without prewarp.

Default: 0

Output Arguments

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Option set for `d2c`, returned as an `d2cOptions` option set.

Examples

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Consider the following discrete-time transfer function.

`$H\left(z\right)=\frac{z+1}{{z}^{2}+z+1}$`

Create the discrete-time transfer function with a sample time of 0.1 seconds.

`Hd = tf([1 1],[1 1 1],0.1);`

Specify the discretization method as bilinear (Tustin) approximation and the prewarp frequency as 20 rad/seconds.

`opts = d2cOptions('Method','tustin','PrewarpFrequency',20);`

Convert the discrete-time model to continuous-time using the specified discretization method.

`Hc = d2c(Hd,opts);`

You can use the discretization option set `opts` to discretize additional models using the same options.

References

[1] Franklin, G.F., Powell,D.J., and Workman, M.L., Digital Control of Dynamic Systems (3rd Edition), Prentice Hall, 1997.

Version History

Introduced in R2010a