On Wednesday, November 13, 2019 at 9:11:02 AM UTC+13, gyans...@gmail.com wrote:

> I have a laplace transfer-function
>
> G(s)=k(1+sT)/s*2
>
> which I need the discrete-time version G(z) using impulse invariance method.
>
> Using partial fractions I get
>
> G(s) = c1/s + c2/s^2
>
> c1=kT and c2=k
>
> However when I use Matlab c2d and select "impulse" it gives me a different version though the first term c1 is right. Matlabs second term c2 is negative.
>
> I assume for multiple poles something is different.

Sorted it. Forgot that a double integrator has a Ts^2 term

Reply by ●November 12, 20192019-11-12

I have a laplace transfer-function
G(s)=k(1+sT)/s*2
which I need the discrete-time version G(z) using impulse invariance method.
Using partial fractions I get
G(s) = c1/s + c2/s^2
c1=kT and c2=k
However when I use Matlab c2d and select "impulse" it gives me a different version though the first term c1 is right. Matlabs second term c2 is negative.
I assume for multiple poles something is different.