M
Marco Trapanese
- Jan 1, 1970
- 0
Hello!
I measured the step response of a system. Now, I can find the transfer
function H(s) as a first or second order approximation. Then I'm able to
select the right gains for the PID controller.
The PID itself is implemented into a microcontroller, so it has an ADC
on the input and a DAC on the output.
I don't understand if I can create the PID transfer function in s-domain
G(s) and then convert to z-domain to find the new kp, ki, kd or I have
to convert the whole H(s) to H(z) and then discuss about the PID (in
z-domain).
Another question: to convert either H(s) to H(z) or G(s) to G(z) may I
use the Tustin approximation?
z=(2+Ts)/(2-Ts)
I read this on the "Applied Control Theory for Embedded System" by Tim
Wescott (who I thank for his suggestion to buy the book!) but I'm not
sure about "[the Tustin approximation] is generally useful [...] when
you are converting an inherited analog controller to digital".
Thanks
Marco / iw2nzm
I measured the step response of a system. Now, I can find the transfer
function H(s) as a first or second order approximation. Then I'm able to
select the right gains for the PID controller.
The PID itself is implemented into a microcontroller, so it has an ADC
on the input and a DAC on the output.
I don't understand if I can create the PID transfer function in s-domain
G(s) and then convert to z-domain to find the new kp, ki, kd or I have
to convert the whole H(s) to H(z) and then discuss about the PID (in
z-domain).
Another question: to convert either H(s) to H(z) or G(s) to G(z) may I
use the Tustin approximation?
z=(2+Ts)/(2-Ts)
I read this on the "Applied Control Theory for Embedded System" by Tim
Wescott (who I thank for his suggestion to buy the book!) but I'm not
sure about "[the Tustin approximation] is generally useful [...] when
you are converting an inherited analog controller to digital".
Thanks
Marco / iw2nzm