how to place all poles of state matrix at zero using place command?

i'm trying to place all poles of my 3 by 3 state matrix at zero , im getting the error , 'The "place" command cannot place poles with multiplicity greater than rank(B).'

why cant this command place poles at the same location. If i assign different poles location it works . How to fix this

Answer 1

[Raynier Suresh]

“Place” command uses the pole placement technique, but in this technique if the multiplicity of poles is greater than the rank(B) then solving for gain values in gain matrix would not be possible. Possible solution to keep multiple poles at same location is to use “acker” command which uses the Ackerman formula or to use LQR design, it may solve your problem.

Referring to the following links might be useful:

Pole placement: https://www.mathworks.com/help/control/getstart/pole-placement.html#f2-1031415

LQR: https://www.mathworks.com/help/control/ref/lqr.html#mw_d709501f-89a4-48d7-a2b8-e81c3d121623

[Fethi Bencherki]

acker is for SISO systems , im dealing with MIMO

Answer 2

[Mohanad Elsamadony]

I am dealing with the same problem!!

would you kindly provide me with the soultion if you solve this problem please?

Thank you

[Zhihe YANG]

I think it still cannot be achieved through 'place' function.

If you are dealing with a simple system, maybe try to use the poles like [-1, -1.0001, -1.0002] instead of [-1, -1, -1], and round the final return can help you solve such problem.