If the plant was given as \( G_p(s) = \frac {Kd}{s+d}\)
and the controller for the plant is \( G_c(z) = \frac {1}{az^-^1+bz^-^2}\)
This is what I have done to find the closed loop trasfer function Where K and d = 1 for a unity feedback
\( G_p(s) = \frac {Kd}{s+d} = \frac {1}{s}\) then changing from the S domain to Z domain \( \frac {1}{s}= \frac {1}{1-z^-^1}\) It is this part of the equation I am unsure what to do with. ie multiply it to the controller which what I have done or work out T(z) first with the controller and feedback and then multipy it by \( \frac {1}{1-z^-^1}\)
\( T(z) =\frac{C(z)}{R(z)}= \frac {\frac {1}{1-z^-^1} \times \frac {1}{az^-^1+bz^-^2}}{1+\frac{1}{ az^-^1+bz^-^2}\)
\( T(z) =\frac{C(z)}{R(z)}= \frac {\frac {1}{(1-z^-^1)(az^-^1+bz^-^2)}}{\frac{1+az^-^1+bz^-^2}{ az^-^1+bz^-^2} \)
\(\Rightarrow {\frac {1}{(1-z^-^1)(az^-^1+bz^-^2)}} \time \frac { az^-^1+bz^-^2}{1+az^-^1+bz^-^2} \Rightarrow \frac{1}{(1-z^-^1)(1+az^-^1+bz^-^2)} \)
Is this the correct way to work out the trasfer function T(z)
and the controller for the plant is \( G_c(z) = \frac {1}{az^-^1+bz^-^2}\)
This is what I have done to find the closed loop trasfer function Where K and d = 1 for a unity feedback
\( G_p(s) = \frac {Kd}{s+d} = \frac {1}{s}\) then changing from the S domain to Z domain \( \frac {1}{s}= \frac {1}{1-z^-^1}\) It is this part of the equation I am unsure what to do with. ie multiply it to the controller which what I have done or work out T(z) first with the controller and feedback and then multipy it by \( \frac {1}{1-z^-^1}\)
\( T(z) =\frac{C(z)}{R(z)}= \frac {\frac {1}{1-z^-^1} \times \frac {1}{az^-^1+bz^-^2}}{1+\frac{1}{ az^-^1+bz^-^2}\)
\( T(z) =\frac{C(z)}{R(z)}= \frac {\frac {1}{(1-z^-^1)(az^-^1+bz^-^2)}}{\frac{1+az^-^1+bz^-^2}{ az^-^1+bz^-^2} \)
\(\Rightarrow {\frac {1}{(1-z^-^1)(az^-^1+bz^-^2)}} \time \frac { az^-^1+bz^-^2}{1+az^-^1+bz^-^2} \Rightarrow \frac{1}{(1-z^-^1)(1+az^-^1+bz^-^2)} \)
Is this the correct way to work out the trasfer function T(z)
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