State Space with Disturbance

254 views (last 30 days)
Azaldo Machava
Azaldo Machava on 21 Jan 2021
Commented: Paul on 6 Apr 2023
I have this system:
Xdot = AX +Bu +Fd,
where A,B and F are the system, input distribution and disturbance distribution matrices respectively and X, U and d are the state, control and disturbance vectors respectively.
i have all the matrices data. i want to know how to use matlab to plot the state variables for a step disturbance.
where i am finding problem is because the standard form of state space in matlab is :Xdot = AX +Bu without the distubance vector.
so how do i input my system in Matlab???

Answers (1)

Paul
Paul on 21 Jan 2021
Combine d and u into a single input vector:
Xdot = A*X + [B F] * [u;d]
y = C*X + [D 0]*[u:d] % assuming the disurbance doesn't feed directly into output
sys = ss(A,[B F],C,[D zeros(size(C,1),size(F,2))])
  23 Comments
jana nassereddine
jana nassereddine on 6 Apr 2023
but in this way the disturbances is considered as a manipulated variable, how can we add the disturbance as an input to model predictive control, and with matrix related to the state of the plant model?
Paul
Paul on 6 Apr 2023
Hi jana,
The state space model can have any number of inputs as required to represent the dyanmics of the system under consideration. Some of those inputs will be control inputs, which is what I think you mean by "manipuated variable," that we can influence with compensation, and other inputs will be disturbances that we have no control over. In the Control System Toolbox representations, both types of inputs are lumped together in a single input vector in the model.
Can you show a simple example for what you're concerned about with model predictive control?

Sign in to comment.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!