User`s guide

c2d
11-24
11c2d
Purpose Discretize continuous-time systems
Syntax sysd = c2d(sys,Ts)
sysd = c2d(sys,Ts,method)
Description sysd = c2d(sys,Ts) discretizes t he continuous-time LTI model sys using
zero-order hold on the inputs and a sample time of
Ts seconds.
sysd = c2d(sys,Ts,method) gives access to alternative discretization
schemes. The string
method selects the discretization method among the
following:
Refer to “Continuous/Discrete Conversions of LTI Models” in Chapter 3 for
more detail on these discretization methods.
c2d supports MIMO s ystems (except for the 'matched' method) as well as LTI
models with input delays (
'zoh' and 'foh' methods only).
Example Consider the system
'zoh'
Zero-order hold. The control inputs are assumed piecewise
constant over the sampling period
Ts.
'foh'
Triangle approximation (modified first-order hold, see [1], p.
151). The control inputs are assumed piecewise linear over
the sampling period
Ts.
'tustin'
Bilinear (Tustin) approximation.
'prewarp'
Tustin approximation with frequency prewarping.
'matched'
Matched pole-zero method. See [1], p. 147.
Hs()
s 1
–
s
2
4s 5++
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